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Background Methods Results Conclusions Crimean‐Congo hemorrhagic fever is a tick‐borne zoonotic disease that may be severe and is present in many African countries. We aimed to understand the seroprevalence and risk for Crimean‐Congo hemorrhagic fever virus in Tanzania by testing archived serum samples from patients enrolled in a prospective cohort study.We prospectively enrolled febrile inpatients and outpatients from 2012 through 2014 at two referral hospitals in northern Tanzania. Archived serum samples were tested for Crimean‐Congo hemorrhagic fever virus antibodies initially by a Luminex assay screen followed by confirmation with immunofluorescence assay. Evidence of exposure to Crimean‐Congo hemorrhagic fever virus was defined as antibody detection by Luminex and confirmed by immunofluorescence assay. Questionnaire data were used to construct logistic regression models to understand factors associated with prior exposure to Crimean‐Congo hemorrhagic fever virus. Domains of predictor variables included sociodemographics, livestock‐rearing activities, and environmental factors.Of 735 participants included, antibodies to Crimean‐Congo hemorrhagic fever virus nucleocapsid protein were detected by Luminex assay in 23 (3.1%) and confirmed by immunofluorescence assay in 13 (1.8%). In multivariable logistic regression, prior exposure to Crimean‐Congo hemorrhagic fever virus was associated with self‐report of milking livestock in the past month (adjusted OR [aOR]: 12.6, 95% CI 1.6–99.8) and natural log increase in goat density (head/km2; aOR: 1.7, 95% CI: 1.1–2.7).We show serologic evidence of prior exposure to Crimean‐Congo hemorrhagic fever virus among humans in northern Tanzania. Similar to other settings, our results suggest that exposure is closely linked to livestock activities. Additional research is warranted to understand reservoirs and modes of transmission of Crimean‐Congo hemorrhagic fever virus to humans in northern Tanzania. [ABSTRACT FROM AUTHOR]

The receptor‐binding domain (RBD) of the SARS‐CoV‐2 virus spike protein has emerged as a promising target for the generation of neutralizing antibodies. Although the RBD subunit is more stable than its encoding mRNA, RBD is poorly immunogenic. It is hypothesized that this limitation can be overcome by sustained coadministration with a more potent and optimized adjuvant than standard adjuvants. One such candidate adjuvant, cGAMP, exhibits promising potency via activation of the antiviral STING pathway. Unfortunately, delivery of cGAMP as a therapeutic exhibits poor performance due to poor pharmacokinetics and pharmacodynamics from rapid excretion and degradation. To overcome these limitations, it is sought to create an artificial immunological niche enabling the slow release of cGAMP and RBD to mimic natural infections in which immune‐activating molecules are colocalized with antigen. Specifically, through coencapsulation of cGAMP and RBD in an injectable polymer‐nanoparticle (PNP) hydrogel, the cGAMP‐adjuvanted hydrogel vaccine elicits more potent, durable, and broad antibody responses with improved neutralization as compared to dose‐matched bolus controls and hydrogel‐based vaccines lacking cGAMP. The cGAMP‐adjuvanted hydrogel platform can be further explored for the delivery of other antigens to enhance immunity against a broad range of pathogens. [ABSTRACT FROM AUTHOR]

Vaccines are the most effective tool against COVID‐19 and are generally safe. Very rare and heterogeneous cases of acute liver injury associated to all types of SARS‐CoV‐2 vaccines have been reported, mostly with autoimmune features. Epidemiological studies used heterogeneous diagnostic criteria and included different populations. Immunological studies in selected cases of acute liver injury linked to mRNA SARS‐CoV‐2 vaccines suggest that it has a unique pathophysiology, the vaccine‐encoded spike protein playing a central role in triggering the aberrant immune response. In most series, liver injury was observed more often following the second vaccine dose. Latency from vaccination to the diagnosis of hepatitis was 1–147 days after the last vaccine dose. Raised immunoglobulin G levels and positive anti‐nuclear and/or anti‐smooth muscle antibodies are frequent. The vast majority of reported cases have been treated with corticosteroids, mostly associated with azathioprine. Outcome is generally favourable, but cases requiring liver transplantation or causing death have been reported. The heterogeneous clinical entity of acute liver injury linked to SARS‐CoV‐2 vaccines includes patients requiring long‐term immunosuppression, similarly to autoimmune hepatitis, and patients with self‐limiting liver damage, possibly representing a unique form of autoimmune‐like hepatitis, which we suggest being referred to as SARS‐CoV‐2 vaccine‐associated liver injury (SVALI). Further studies are needed to investigate the pathogenic mechanisms related to the immune response to the spike viral protein in the liver. [ABSTRACT FROM AUTHOR]

G protein‐coupled receptors (GPCRs) are pivotal in cellular signalling and drug targeting. Herpesviruses encode GPCRs (vGPCRs) to manipulate cellular signalling, thereby regulating various aspects of the virus life cycle, such as viral spreading and immune evasion. vGPCRs mimic host chemokine receptors, often with broader signalling and high constitutive activity. This review focuses on the recent advancements in structural knowledge about vGPCRs, with an emphasis on molecular mechanisms of action and ligand binding. The structures of US27 and US28 from human cytomegalovirus (HCMV) are compared to their closest human homologue, CX3CR1. Contrasting US27 and US28, the homotrimeric UL78 structure (HCMV) reveals more distance to chemokine receptors. Open reading frame 74 (ORF74; Kaposi's sarcoma‐associated herpesvirus) is compared to CXCRs, whereas BILF1 (Epstein–Barr virus) is discussed as a putative lipid receptor. Furthermore, the roles of vGPCRs in latency and lytic replication, reactivation, dissemination and immune evasion are reviewed, together with their potential as drug targets for virus infections and virus‐related diseases. [ABSTRACT FROM AUTHOR]

Host cell-encoded deaminases act as antiviral restriction factors to impair viral replication and production through introducing mutations in the viral genome. We sought to understand whether deaminases are involved in SARS-CoV-2 mutation and replication, and how the viral factors interact with deaminases to trigger these processes. Here, we show that APOBEC and ADAR deaminases act as the driving forces for SARS-CoV-2 mutagenesis, thereby blocking viral infection and production. Mechanistically, SARS-CoV-2 nucleocapsid (N) protein, which is responsible for packaging viral genomic RNA, interacts with host deaminases and co-localizes with them at stress granules to facilitate viral RNA mutagenesis. N proteins from several coronaviruses interact with host deaminases at RNA granules in a manner dependent on its F17 residue, suggesting a conserved role in modulation of viral mutagenesis in other coronaviruses. Furthermore, mutant N protein bearing a F17A substitution cannot localize to deaminase-containing RNA granules and leads to reduced mutagenesis of viral RNA, providing support for its function in enhancing deaminase-dependent viral RNA editing. Our study thus provides further insight into virus-host cell interactions mediating SARS-CoV-2 evolution. Synopsis: Host cell-encoded deaminases act as innate restriction factors that enhance viral genome mutation and evolution. This study shows that SARS-CoV-2 nucleocapsid (N) protein interacts with host deaminases at RNA granules, thus promoting viral mutagenesis. N protein specifically interacts with host ADAR and APOBEC deaminases. N protein localises to deaminase-containing RNA granules via RNA-dependent phase separation. N protein promotes deaminase-induced RNA editing of SARS-CoV-2 genome. N protein with a F17A mutation fails to localise to deaminase-containing RNA granules and reduces host deaminase-dependent mutagenesis of SARS-CoV-2 genome. Coronaviral N protein interacts and co-condensates with host ADAR and APOBEC deaminases to promote viral RNA editing. [ABSTRACT FROM AUTHOR]

ABSTRACT Background Aim Methods Results Conclusion Platelets, besides being traditionally associated with hemostasis, have been recently positioned as immune cells. Alterations in platelet number and function have been reported in some viral infections. Zika virus (ZIKV) and Dengue virus (DENV) are arboviruses that encode for a non‐structural protein 1 (NS1). NS1 is mainly involved in the viral replication process and can also be secreted by infected cells and has been associated with immune response evasion. The assessment of platelet reactivity against these viral agents and their proteins, through the use of different innovative technologies such as flow cytometry (FC), atomic force microscopy (AFM), and quartz crystal microbalance (QCM), will allow further study of the pathophysiology of these emerging diseases.The aim of this study was to assess platelet reactivity to ZIKV and DENV NS1 protein through the use of FC, AFM, and QCM.Platelet‐rich plasma (PRP) was stimulated with ZIKV and DENV NS1 protein in individual assays. The expression of P‐selectin and the activity of the glycoprotein IIb‐IIIa, platelet activation markers, were assessed by FC, morphological changes were assessed by AFM, and interaction between NS1 protein and platelet were evaluated by QCM.An increased expression of P‐selectin and GP IIb‐IIIa activity (p < 0.001) was observed when PRP was stimulated with ZIKV and DENV NS1 proteins. AFM images showed an increase in cell size and the appearance of pseudopods upon stimulation with the viral proteins. QCM results showed a significant increase in the oscillation frequency of the quartz precoated with ZIKV or DENV NS1 when PRP was injected (p < 0.001).FC, AFM, and QCM are techniques that can be used in the study of platelet response to viral structures such as NS1 protein, broadening the range of existing methodologies in the study of these cells. It is imperative to study platelets in arboviral infections to better understand their involvement in these diseases. [ABSTRACT FROM AUTHOR]

The identification of host factors with antiviral potential is important for developing effective prevention and therapeutic strategies against SARS-CoV-2 infection. Here, by using immortalized cell lines, intestinal organoids, ex vivo intestinal tissues and humanized ACE2 mouse model as proof-of-principle systems, we have identified lipolysis-stimulated lipoprotein receptor (LSR) as a crucial host defense factor against SARS-CoV-2 infection in the small intestine. Loss of endogenous LSR enhances ACE2-dependent infection by SARS-CoV-2 Spike (S) protein-pseudotyped virus and authentic SARS-CoV-2 virus, and exogenous administration of LSR protects against viral infection. Mechanistically, LSR interacts with ACE2 both in cis and in trans, preventing its binding to S protein, and thus inhibiting viral entry and S protein-mediated cell–cell fusion. Finally, a small LSR-derived peptide blocks S protein binding to the ACE2 receptor in vitro. These results identify both a previously unknown function for LSR in antiviral host defense against SARS-CoV-2, with potential implications for peptide-based pan-variant therapeutic interventions. Synopsis: Host cell factors that affect the interaction of SARS-CoV-2 Spike (S) protein with its receptor ACE2 can modulate SARS-CoV-2 infection. This study shows that lipolysis-stimulated lipoprotein receptor (LSR) acts as a defense factor against SARS-CoV-2 by impairing S protein binding to ACE2. LSR suppresses SARS-CoV-2 infection in the small intestine. LSR blocks viral entry and restricts S protein-mediated cell–cell fusion. LSR interacts with ACE2 both in cis and in trans, preventing its binding to S protein. Lipolysis-stimulated lipoprotein receptor (LSR) and its peptide derivative inhibit SARS-CoV-2 entry into host cells by blocking interaction between viral Spike protein and its ACE2 receptor. [ABSTRACT FROM AUTHOR]

The Zika virus (ZIKV) is a global health threat due to its rapid spread and severe health implications, including congenital abnormalities and neurological complications. Differentiating ZIKV from other arboviruses such as dengue virus (DENV) is crucial for effective diagnosis and treatment. This study presents the development of a biosensor for detecting the ZIKV non‐structural protein 1 (NS1) using gold nanoparticles (AuNPs) functionalized with monoclonal antibodies employing dynamic light scattering (DLS). The biosensor named ZINS1‐mAb‐AuNP exhibited specific binding to the ZIKV NS1 protein, demonstrating high colloidal stability indicated by a hydrodynamic diameter (DH) of 140 nm, detectable via DLS. In the absence of the protein, the high ionic strength medium caused particle aggregation. This detection method showed good sensitivity and specificity, with a limit of detection (LOD) of 0.96 μg mL−1, and avoided cross‐reactivity with DENV2 NS1 and SARS‐CoV‐2 spike proteins. The ZINS1‐mAb‐AuNP biosensor represents a promising tool for the early and accurate detection of ZIKV, facilitating diagnostic and treatment capabilities for arboviral infections. [ABSTRACT FROM AUTHOR]

ABSTRACT Many plant viruses modify the phenotype of their hosts, which may influence the behaviour of their vectors and facilitate transmission. Among them is the turnip yellows virus (TuYV), which can modify the orientation, feeding, and performance of its main aphid vector, Myzus persicae. However, the virus factors driving these mechanisms have not been elucidated. In this study, we compared the feeding behaviour and fecundity of aphids on TuYV‐infected and transgenic Arabidopsis thaliana expressing individual TuYV proteins (CP, RT and P0) to define the role of these proteins in aphid–plant interactions. Aphids on TuYV‐infected plants had shorter pathway phases and ingested phloem sap for longer times, which is expected to promote the acquisition of the phloem‐limited TuYV. No change in aphid fecundity was observed on TuYV‐infected plants. The transmission‐conducive feeding behaviour changes could be fully reproduced by phloem‐specific expression of the capsid protein (CP) in transgenic plants, whereas expression of P0 had minor and RT had no effects on aphid feeding behaviour. We then carried out a metabolomic analysis to determine plant compounds that could be involved in the modification of the aphid behaviour. A few metabolites were specific for TuYV‐infected or CP‐transgenic A. thaliana, and are good candidates for inducing behavioural changes. [ABSTRACT FROM AUTHOR]

Wheat yellow mosaic virus (WYMV) causes severe viral wheat disease in Asia. The WYMV P1 protein encoded by RNA2 has viral suppressor of RNA silencing (VSR) activity to facilitate virus infection, however, VSR activity has not been identified for P2 protein encoded by RNA2. In this study, P2 protein exhibited strong VSR activity in Nicotiana benthamiana at the four‐leaf stage, and point mutants P70A and G230A lost VSR activity. Protein P2 interacted with calmodulin (CaM) protein, a gene‐silencing associated protein, while point mutants P70A and G230A did not interact with it. Competitive bimolecular fluorescence complementation and competitive co‐immunoprecipitation experiments showed that P2 interfered with the interaction between CaM and calmodulin‐binding transcription activator 3 (CAMTA3), but the point mutants P70A and G230A could not. Mechanical inoculation of wheat with in vitro transcripts of WYMV infectious cDNA clone further confirmed that VSR‐deficient mutants P70A and G230A decreased WYMV infection in wheat plants compared with the wild type. In addition, RNA silencing, temperature, ubiquitination and autophagy had significant effects on accumulation of P2 protein in N. benthamiana leaves. In conclusion, WYMV P2 plays a VSR role in N. benthamiana and promotes virus infection by interfering with calmodulin‐related antiviral RNAi defense. Summary statement: Wheat yellow mosaic virus P2 protein exerts VSR activity in Nicotiana benthamiana by interfering with the CaM–CAMTA3 interaction to facilitate virus efficient systemic infection. [ABSTRACT FROM AUTHOR]

Background and Purpose: To date, there are limited options for severe Coronavirus disease 2019 (COVID‐19), caused by SARS‐CoV‐2 virus. As ADP‐ribosylation events are involved in regulating the life cycle of coronaviruses and the inflammatory reactions of the host; we have, here, assessed the repurposing of registered PARP inhibitors for the treatment of COVID‐19. Experimental Approach: The effects of PARP inhibitors on virus uptake were assessed in cell‐based experiments using multiple variants of SARS‐CoV‐2. The binding of rucaparib to spike protein was tested by molecular modelling and microcalorimetry. The anti‐inflammatory properties of rucaparib were demonstrated in cell‐based models upon challenging with recombinant spike protein or SARS‐CoV‐2 RNA vaccine. Key Results: We detected high levels of oxidative stress and strong PARylation in all cell types in the lungs of COVID‐19 patients, both of which negatively correlated with lymphocytopaenia. Interestingly, rucaparib, unlike other tested PARP inhibitors, reduced the SARS‐CoV‐2 infection rate through binding to the conserved 493–498 amino acid region located in the spike‐ACE2 interface in the spike protein and prevented viruses from binding to ACE2. In addition, the spike protein and viral RNA‐induced overexpression of cytokines was down‐regulated by the inhibition of PARP1 by rucaparib at pharmacologically relevant concentrations. Conclusion and Implications: These results point towards repurposing rucaparib for treating inflammatory responses in COVID‐19. [ABSTRACT FROM AUTHOR]

Nanopores offer significant advantages in biosensing. Conventional nanopore sensors require probe modification within the pore, and there are two major obstacles: inhomogeneity of probe modification within the pore, and distortion of the detection signal due to the uncontrollable dynamics of the target within the pore. Here, we constructed a cell‐sensing analogue nanopore (CeSa‐nanopore), by coating the outer surface of the nanopore with cell membrane. The inhomogeneity of probe modification and the uncontrollable kinetics of target‐probe binding were also addressed. Specific cells are selected to prepare CeSa‐nanopore, for example, cells with high expression of angiotensin‐converting enzyme 2 (ACE2) are used to achieve the detection of SARS‐CoV‐2. When SARS‐CoV‐2 binds to CeSa‐nanopore the surface potential changes, causing a change in the ionic current, thus enabling its detection with a detection rate of 100 %. In addition, the detection of different proteins, such as follicle‐stimulating hormone (FSH), can be achieved by changing the cell membrane coating. The identification of cancer cells in ascites can also be achieved by utilizing homologous targeting between cancer cells. Importantly, the use of CeSa‐nanopores for the detection of these targets eliminates the need for pre‐processing and significantly reduces detection time. [ABSTRACT FROM AUTHOR]

SUMMARY N‐acetylgalactosamine (GalNAc)‐binding lectin is one of the beneficial lectins because it has the ability to bind to glycoproteins or glycolipids containing GalNAc. Its potential applications include use as a drug delivery system, as well as for diagnostic tools and therapeutic interventions. Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) spike proteins are known to be heavily glycosylated, and GalNAc‐binding lectin can potentially bind with these glycoproteins. The present study specifically investigated the interactions between GalNAc‐binding lectin from Kappaphycus alvarezii (Rhodophyta) and the sugars and glycoproteins present on the S protein of the SARS‐CoV‐2 virus. The GalNAc‐specific lectin was successfully isolated from K. alvarezii var. tangan‐tangan (Loving Beauty) and purified using a Sepharose 6B‐GalNAc affinity column. This lectin demonstrated stability within the temperature range 30–80°C and pH range 3–9. The minimum inhibitory concentration of this lectin was determined to be 0.001 mg mL−1. Sugar specificity tests confirmed its ability to bind to the sugars and glycoproteins reported to be present on the S protein of the SARS‐CoV‐2 virus envelope. These results suggest that the potential of GalNAc‐specific lectin from K. alvarezii can be further explored, making it a promising candidate for therapeutic interventions against coronavirus. [ABSTRACT FROM AUTHOR]

The ongoing global threats posed by COVID‐19 pandemic, catalyzed by SARS‐CoV‐2, underscores the pressing need for effective antiviral strategies. The viral non‐structural protein 1 (Nsp1) significantly influences pathogenicity by impeding host protein expression and enhancing viral RNA translation through its interaction with the stem‐loop 1 (SL1) in the 5′ untranslated region (UTR). We have developed a novel dual‐luciferase reporter assay, designed to investigate the critical Nsp1–SL1 interaction, and identified P23E02 as a potential inhibitor. Our investigation, combining molecular docking studies and alanine mutagenesis, has unveiled that P23E02 disrupts Nsp1–40S ribosomal subunit interaction, liberating translational inhibition and empowering host antiviral responses. P23E02 exhibits antiviral efficacy against various sarbecoviruses, making it a promising candidate for combatting COVID‐19 and related diseases. This study underscores the therapeutic potential of targeting the Nsp1/SL1 axis and lays the foundation for innovative antiviral interventions, ultimately fortifying global preparedness against future viral threats. [ABSTRACT FROM AUTHOR]

A high pathogenicity avian influenza (HPAI) subtype H7N6 virus emerged in South African poultry in 2023 and later spread to Mozambique, the first documented emergence of H7 HPAI in the African continent. A total of 6.82 million birds succumbed to the disease or were culled, representing about 20% of the South African egg‐laying flock and almost 30% of the broiler breeder flock. The complete genomes of 68 outbreak viruses were sequenced and analyzed, tracing the phylogenetic origins of the ancestral H7N6 virus to a reassortment of various subtypes that circulated in southern African wild birds. Molecular clock analysis determined that the virus emerged in the first week of May 2023, probably in a smallholder chicken flock, before spreading to commercial farms, where the disease was first reported in early June. The multibasic hemagglutinin protein cleavage site (HA0) was derived from a nonhomologous recombination event with chicken 28S ribosomal ribonucleic acid (RNA). Few genetic markers associated with an increased risk to humans were present in the translated viral proteins. The intravenous pathogenicity index (IVPI) value of the index case isolate was 1.67, reflecting that 50% of the specific pathogen‐free chickens died within 4 days of infection. Surviving birds showing mostly mild clinical signs and recovered by day 10 postinfection. Prior to death, chickens shed the virus primarily through the respiratory route, with lower amounts shed from the cloaca, but in the survivors, the virus was still being shed from the cloaca on day 10. Fomites were the likely source of disease spread between farms, and the amount of H7N6 HPAI virus per gram of feces was calculated at ~383,193 (5.58 log10) egg infectious dose 50 (EID50) equivalents, chicken feather follicles contained on average 739,712.43 (5.87 log10) EID50 equivalents, and 20 µg of feather dust contained 14,976.96 (4.175 log10) EID50 equivalents. [ABSTRACT FROM AUTHOR]

Plant resistance, which acts as a selective pressure that affects viral population fitness, leads to the emergence of resistance‐breaking virus strains. Most recessive resistance to potyviruses is related to the mutation of eukaryotic translation initiation factor 4E (eIF4E) or its isoforms that break their interactions with the viral genome‐linked protein (VPg). In this study, we found that the VPg α1–α2 loop, which is essential for binding eIF4E, is the most variable domain of papaya ringspot virus (PRSV) VPg. PRSV VPg with the naturally occurring amino acid substitution of K105Q or E108G in the α1–α2 loop fails to interact with watermelon (Citrullus lanatus) eIF4E but interacts with watermelon eIF(iso)4E instead. Moreover, PRSV carrying these mutations can break the eIF4E‐mediated resistance to PRSV in watermelon accession PI 244019. We further revealed that watermelon eIF(iso)4E with the amino acid substitutions of DNQS to GAAA in the cap‐binding pocket could not interact with PRSV VPg with natural amino acid substitution of K105Q or E108G. Therefore, our finding provides a precise target for engineering watermelon germplasm resistant to resistance‐breaking PRSV isolates. [ABSTRACT FROM AUTHOR]

Lateral flow immunoassays (LFIAs) are easy‐to‐use antigen tests that provide different signal readouts, with colorimetric readouts being the most commonly used. However, these analytical devices have relatively low sensitivity and produce semiquantitative results, limiting their diagnostic applications. Herein, we address these challenges by implementing a digital surface‐enhanced Raman spectroscopy (SERS)‐based LFIA for the accurate and ultrasensitive quantitative detection of SARS‐CoV‐2 nucleocapsid (N) protein. Compared with average SERS intensity measurements, the digital approach allowed to overcome fluctuations in Raman scattering signals, thereby increasing the analytical sensitivity of the assay. Our method exhibited a quantification range of the viral protein in nasal swabs from 0.001 to 10 pg mL−1, and a limit of detection down to 1.9 aM (0.9 fg mL−1), improving colorimetric LFIAs and conventional‐SERS‐based LFIAs by several orders of magnitude. Importantly, this approach shows an analytical sensitivity of 0.03 TCID50 mL−1, which is greater than that reported by other immunoassays. In conclusion, we successfully demonstrate the robust detection and quantification of SARS‐CoV‐2N protein in nasal swabs at ultralow concentrations. The improvement in the sensitivity of LFIA by digital SERS may pave the way to translate this technology into the diagnostic arena for the ultrasensitive detection of microbes and disease biomarkers. [ABSTRACT FROM AUTHOR]

Summary: The development of plant virus‐based expression systems has expanded rapidly owing to their potential applications in gene functional and disease resistance research, and industrial production of pharmaceutical proteins. However, the low yield of certain proteins, especially high‐molecular‐mass proteins, restricts the production scale. In this study, we observed that the tobacco mosaic virus (TMV)‐mediated expression of a foreign protein was correlated with the amount of the movement protein (MP) and developed a TMV‐derived pAT‐transMP vector system incorporating trans‐complementation expression of MP. The system is capable of efficient expression of exogenous proteins, in particular those with a high molecular mass, and enables simultaneous expression of two target molecules. Furthermore, viral expression of competent CRISPR‐Cas9 protein and construction of CRISPR‐Cas9‐mediated gene‐editing system in a single pAT‐transMP construct was achieved. The results demonstrated a novel role for TMV‐MP in enhancing the accumulation of a foreign protein produced from the viral vector or a binary expression system. Further investigation of the mechanism underlying this role will be beneficial for optimization of plant viral vectors with broad applications. [ABSTRACT FROM AUTHOR]

Global pandemics caused by pathogenic viruses have highlighted the need to develop effective and sustainable materials to defend against these viruses. However, most commercial viral disinfection materials rely on precious metals, which are toxic. In this study, an engineered living material based on Bacillus subtilis biofilms is presented that can effectively remove Influenza A virus and SARS‐CoV‐2 from water. First, B. subtilis biofilm is used to display the H1N1 and H5N1 specific binding peptide C40 and SARS‐CoV‐2 specific binding peptide SBP1; thus, the biofilm materials has outstanding efficacy against H1N1, H5N1, and SARS‐CoV‐2 pseudovirus from water. In addition to capturing the virus, these biofilm materials can also inactivate the virus by secreting alkaline protease AprE, which effectively degrades the viral proteins at temperatures of 4, 16, 25, and 37 °C. Furthermore, to constrain bacterial growth and prevent the leakage of genetically modified organisms, a suicide genetic circuit using the quorum‐sensing system ComQXPA to control Lytc expression is constructed, leading to bacterial lysis. Overall, this study demonstrates a novel, effective, and sustainably engineered living material for preventing viral transmission. This material provides a safeguard for public health and promotes environmentally friendly governance. [ABSTRACT FROM AUTHOR]

Targeted protein degradation has been widely adopted as a new approach to eliminate both established and previously recalcitrant therapeutic targets. Here, it is reported that the development of small molecule degraders of the envelope (E) protein of dengue virus. Two classes of bivalent E‐degraders are developed by linking two previously reported E‐binding small molecules, GNF‐2, and CVM‐2‐12‐2, to a glutarimide‐based recruiter of the CRL4CRBN ligase to effect proteosome‐mediated degradation of the E protein. ZXH‐2‐107 (based on GNF‐2) is an E‐degrader with ABL inhibitory activity while ZXH‐8‐004 (based on CVM‐2‐12‐2) is a selective and potent E‐degrader. These two compounds provide proof of concept that difficult‐to‐drug targets such as a viral envelope protein can be effectively eliminated using a bivalent degrader and provide starting points for the future development of a new class of direct‐acting antiviral drugs. [ABSTRACT FROM AUTHOR]

Arboviruses, transmitted by medical arthropods, pose a serious health threat worldwide. During viral infection, Post Translational Modifications (PTMs) are present on both host and viral proteins, regulating multiple processes of the viral lifecycle. In this study, a mammalian E3 ubiquitin ligase WWP2 (WW domain containing E3 ubiquitin ligase 2) is identified, which interacts with the NS1 protein of Zika virus (ZIKV) and mediates K63 and K48 ubiquitination of Lys 265 and Lys 284, respectively. WWP2‐mediated NS1 ubiquitination leads to NS1 degradation via the ubiquitin‐proteasome pathway, thereby inhibiting ZIKV infection in mammalian hosts. Simultaneously, it is found Su(dx), a protein highly homologous to host WWP2 in mosquitoes, is capable of ubiquitinating NS1 in mosquito cells. Unexpectedly, ubiquitination of NS1 in mosquitoes does not lead to NS1 degradation; instead, it promotes viral infection in mosquitoes. Correspondingly, the NS1 K265R mutant virus is less infectious to mosquitoes than the wild‐type (WT) virus. The above results suggest that the ubiquitination of the NS1 protein confers different adaptations of ZIKV to hosts and vectors, and more importantly, this explains why NS1 K265‐type strains have become predominantly endemic in nature. This study highlights the potential application in antiviral drug and vaccine development by targeting viral proteins' PTMs. [ABSTRACT FROM AUTHOR]

Spike (S) glycoprotein is the largest structural protein of SARS‐CoV‐2 virus and the main one involved in anchoring of the host receptor ACE2 through the receptor binding domain (RBD). S protein secondary structure is of great interest for shedding light on various aspects, from functionality to pathogenesis, finally to spectral fingerprint for the design of optical biosensors. In this paper, the secondary structure of SARS‐CoV‐2 S protein and its constituting components, namely RBD, S1 and S2 regions, are investigated at serological pH by measuring their amide I infrared absorption bands through Attenuated Total Reflection Infrared (ATR‐IR) spectroscopy. Experimental data in combination with MultiFOLD predictions, Define Secondary Structure of Proteins (DSSP) web server and Gravy value calculations, provide a comprehensive understanding of RBD, S1, S2, and S proteins in terms of their secondary structure content, conformational order, and interaction with the solvent. [ABSTRACT FROM AUTHOR]

ABSTRACT The human papillomavirus (HPV) 33 is a high‐risk strain that causes lesions with potential cancerous outcomes. Its E2 protein regulates the viral protein transcription and life cycle maintenance. The DNA binding domain (DBD) of the E2 protein plays a crucial role in the viral life cycle. The DBD region of the E2 protein is particularly interesting for targeting and finding potential inhibitors to inhibit its function or dimerization. Given the limited research on HPV 33 and its proteins, the present work delved into the interaction of two natural polyphenolic compounds, resveratrol, and baicalein, with the E2 DBD of HPV 33 using biophysical and in silico studies. Fluorescence studies of the E2 DBD‐polyphenol complexes showed fluorescence quenching with a binding constant of the order of 106 M−1. Circular dichroism data reveal conformational changes upon binding with the polyphenols, possibly due to distinct binding sites of the E2 DBD. Differential scanning calorimetry exhibited higher melting temperatures for the two complexes than alone DBD, suggesting the complexes' stability. ITC experiment suggested favorable binding reactions with kd values in the micromolar range. Molecular docking and dynamic simulation studies revealed that the resveratrol binds to the helical region and baicalein near the central dimeric interface of E2 DBD with a good binding affinity, forming a stable protein‐ligand complex during the run of 100 ns simulation. Therefore, the current study identifies both polyphenolic compounds as promising candidates for potential antiviral drug development. [ABSTRACT FROM AUTHOR]

BK polyomavirus infection is an important cause of graft loss in transplant patients, however, currently available therapies lack effectiveness against this pathogen. Identification of immunological targets for potential treatments is therefore necessary. The aim of this study was to predict candidates of immunodominant epitopes within four BK virus proteins (VP1, VP2, VP3 and LTA) using PBMCs from 44 healthy donors. We used the ELISpot epitope mapping method to evaluate the T‐cell response, and HLA‐peptide binding was predicted using the NetMHCpan algorithm. A total of 11 potential peptides were selected for VP1, 3 for VP2/VP3 and 13 for LTA. Greater reactivity was observed for VP1 and LTA proteins compared with VP2/VP3. Most of the peptides selected as potential immunodominant candidates were restricted towards several HLA class I and II alleles, with predominant HLA class I binding by computational predictions. Based on these findings, the sequences of the selected immunodominant epitopes candidates and their corresponding HLA restrictions could contribute to the optimisation of functional assays and aid in the design and improvement of immunotherapy strategies against BK virus infections. [ABSTRACT FROM AUTHOR]

Adult T cell leukaemia (ATL), caused by infection with human T‐ lymphotropic virus type 1 (HTLV‐1), is often complicated by hypercalcemia and osteolytic lesions. Therefore, we studied the communication between patient‐derived ATL cells (ATL‐PDX) and HTLV‐1 immortalized CD4+ T cell lines (HTLV/T) with osteoclasts and their effects on bone mass in mice. Intratibial inoculation of some HTLV/T leads to a profound local decrease in bone mass similar to marrow‐replacing ATL‐PDX, despite the fact that few HTLV/T cells persisted in the bone. To study the direct effect of HTLV/T and ATL‐PDX on osteoclasts, supernatants were added to murine and human osteoclast precursors. ATL‐PDX supernatants from hypercalcemic patients promoted the formation of mature osteoclasts, while those from HTLV/T were variably stimulatory, but had largely consistent effects between human and murine cultures. Interestingly, this osteoclastic activity did not correlate with expression of osteoclastogenic cytokine receptor activator of nuclear factor kappa‐B ligand (RANKL), suggesting an alternative mechanism. HTLV/T and ATL‐PDX produce small extracellular vesicles (sEV), known to facilitate HTLV‐1 infection. We hypothesized that these sEV also mediate bone loss by targeting osteoclasts. We isolated sEV from both HTLV/T and ATL‐PDX, and found they carried most of the activity found in supernatants. In contrast, sEV from uninfected activated T cells had little effect. Analysis of sEV (both active and inactive) by mass spectrometry and electron microscopy confirmed absence of RANKL and intact virus. Viral proteins Tax and Env were only present in sEV from the active, osteoclast‐stimulatory group, along with increased representation of proteins involved in osteoclastogenesis and bone resorption. sEV from osteoclast‐active HTLV/T injected over mouse calvaria in the presence of low‐dose RANKL caused more osteolysis than osteoclast‐inactive sEV or RANKL alone. Thus, HTLV‐1 infection of T cells can cause release of sEV with strong osteolytic potential, providing a mechanism beyond RANKL production that modifies the bone microenvironment, even in the absence of overt leukaemia. [ABSTRACT FROM AUTHOR]

Cyclosporin A (CsA), an immunosuppressive drug used in transplant recipients, inhibits graft rejection by binding to cyclophilins and competitively inhibiting calcineurin. While concerns about respiratory infections in immunosuppressed patients exist, contradictory data emerged during the COVID‐19 pandemic, prompting investigations into CsA's impact on viral infections. This study explores CsA's antiviral effects on SARS‐CoV‐2 Omicron BA.1, Delta variants, and human parainfluenza virus 3 (HPIV3) using an ex vivo model of human airway epithelium (HAE). CsA exhibited a dose‐dependent antiviral effect against the SARS‐CoV‐2 Delta variant, reducing viral load over 10 days. However, no significant impact was observed against SARS‐CoV‐2 Omicron or HPIV3, indicating a virus‐specific effect. At high concentrations, CsA was associated with an increase of IL‐8 and a decrease of IFNλ expression in infected and noninfected HAE. This study highlights the complexity of CsA's antiviral mechanisms, more likely involving intricate inflammatory pathways and interactions with specific viral proteins. The research provides novel insights into CsA's effects on respiratory viruses, emphasizing the need for understanding drug–virus interactions in optimizing therapeutic approaches for transplant recipients and advancing knowledge on immunosuppressive treatments' implications on respiratory viral infections. Limitations include the model's inability to assess T lymphocyte activation, suggesting the necessity for further comprehensive studies to decipher the intricate dynamics of immunosuppressive treatments on respiratory viral infections. [ABSTRACT FROM AUTHOR]

BACKGROUND: Telosma mosaic virus (TelMV, Potyvirus, Potyviridae) is an emerging viral pathogen that threatens passion fruit plantations worldwide. However, an efficient strategy for controlling such a virus is not yet available. Cross protection is a phenomenon in which pre‐infection of a plant with one mild strain prevents or delays subsequent infection by the same or closely related virus. HC‐Pro is the potyviral encoded multifunctional protein involved in several steps of viral infection, including multiplication, movement, transmission and RNA silencing suppression. In this study, we tested whether it is possible to generate attenuated viral strains capable of conferring protection against severe TelMV infection by manipulating the HC‐Pro gene. RESULTS: By introducing point mutation into the conserved motif FRNK of HC‐Pro that is essential for RNA silencing suppression, we have successfully obtained three attenuated mutants of TelMV (R181K, R181D, and R181E, respectively). These attenuated TelMV mutants could systemically infect passion fruit plants without noticeable symptoms. Pre‐inoculation of one of these attenuated mutants confers efficient protection against subsequent infection by severe TelMV strain. Moreover, we demonstrated that the HC‐Pros harbored by the attenuated mutants exhibit reduced RNA silencing suppression activity in Nicotiana benthamiana leaves. CONCLUSION: The attenuated TelMV mutants developed in this study that are suitable for cross protection offer a practical, powerful tool to fight against TelMV for sustainable passion fruit production. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Nuclear factor κB (NF‐κB) plays a crucial role in various cellular processes, including inflammatory and immune responses. Its activation is tightly regulated by the IKK (IκB kinase) complex. Upon severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection, the virus is initially recognized by the innate immune system and typically activates the NF‐κB pathway, leading to a severe inflammatory response. However, the influence of viral proteins upon pro‐inflammatory pathway is complicated. Here, we demonstrated that the viral protein nsp3 of SARS‐CoV‐2 exhibits an unusual function, which attenuated the NF‐κB‐mediated inflammatory response against SARS‐CoV‐2 infection in a unique manner. nsp3 interacted with the essential NF‐κB modulator NEMO/IKKγ and promoted its polyubiquitylation via the E3 ubiquitin ligase CBL (Cbl Proto‐Oncogene). Consequently, polyubiquitylated NEMO undergoes proteasome‐dependent degradation, which disrupts NF‐κB activation. Moreover, we found that the SARS unique domain (SUD) in nsp3 of SARS‐CoV‐2 is essential for inducing NEMO degradation, whereas this function is absent in SUD of SARS‐CoV. The reduced activation of pro‐inflammatory response at an early stage could mask the host immune response and faciliate excessive viral replication. Conversely, this finding may partially explain why SARS‐CoV‐2 causes a less inflammatory reaction than SARS‐CoV, resulting in more mild or moderate COVID‐19 cases and greater transmissibility. Given that NEMO is important for NF‐κB activation, we propose that inhibiting polyubiquitylation and degradation of NEMO upon SARS‐CoV‐2 infection is a novel strategy to modulate the host inflammatory response. [ABSTRACT FROM AUTHOR]

During in silico research, based on molecular docking, dynamics simulation, network pharmacology and ADMET (absorption, distribution, metabolism, excretion, and toxicity) property, 31 potential compounds are obtained from seven Chinese medicinal herbs containing coumarins. Moreover, mechanism researches discover these compounds treat influenza A virus through key targets TLR4, MMP9, and IL6 (high fever, acute respiratory distress syndrome), MAPK1 and MAPK3 (MAPK signaling pathway, viral RNP export and viral protein expression), CASP3 (apoptosis), EP300 and CREBBP (viral myocarditis, chemoattraction of monocytes and macrophages, T cell activation antibody response). Further experimental verification finds that 22 of 31 compounds have various degrees of anti‐influenza virus activities. Moreover, 12 of 22 compounds have better biological activities (IC50=0.1609–54.95 μM) than oseltamivir (IC50=114.3 μM). 3 of 12 compounds have better antioxidant activities (IC50=2.087–3.796 μM) than vitamin C (IC50=5.004 μM). Therefore, ellagic acid, hyperoside, and fraxetin are promising multi‐target lead compounds for influenza virus therapy. Meanwhile, the present study offers compelling evidence for the development of novel antiviral medications. [ABSTRACT FROM AUTHOR]

Summary: Catalase (CAT) is the main reactive oxygen species (ROS)‐scavenging enzyme in plants and insects. However, it remains elusive whether and how insect saliva CAT suppresses ROS‐mediated plant defense, thereby promoting initial virus transmission by insect vectors.Here, we investigated how leafhopper Recilia dorsalis catalase (RdCAT) was secreted from insect salivary glands into rice phloem, and how it was perceived by rice chaperone NO CATALASE ACTIVITY1 (OsNCA1) to scavenge excessive H2O2 during insect‐to‐plant virus transmission.We found that the interaction of OsNCA1 with RdCAT activated its enzymatic activity to decompose H2O2 in rice plants during leafhopper feeding. However, initial insect feeding did not significantly change rice CATs transcripts. Knockout of OsNCA1 in transgenic lines decreased leafhopper feeding‐activated CAT activity and caused higher H2O2 accumulation. A devastating rice reovirus activated RdCAT expression and promoted the cosecretion of virions and RdCAT into leafhopper salivary cavities and ultimately into the phloem. Virus‐mediated increase of RdCAT secretion suppressed excessive H2O2, thereby promoting host attractiveness to insect vectors and initial virus transmission.Our findings provide insights into how insect saliva CAT is secreted and perceived by plant chaperones to suppress the early H2O2 burst during insect feeding, thereby facilitating viral transmission. [ABSTRACT FROM AUTHOR]

Genetically encoded peptide libraries are at the forefront of de novo drug discovery. The RaPID (Random Nonstandard Peptides Integrated Discovery) platform stands out due to the unique combination of flexible in vitro translation (FIT) and mRNA display. This enables the incorporation of non‐canonical amino acids, improving chemical diversity and allowing macrocyclisation of the peptide library. The resulting constrained peptides are valued for their strong binding affinity and stability, especially in the context of protein‐protein interactions. In response to SARS‐CoV‐2, the causative agent of the COVID‐19 pandemic, the RaPID system proved valuable in identifying high‐affinity ligands of viral proteins. Among many peptide ligands of SARS‐CoV‐2 spike and main protease (Mpro), several macrocycles stand out for their exceptional binding affinities. Structural data showcases distinct binding modes in complex with the receptor‐binding domain (RBD) of the spike glycoprotein or the catalytic active site of Mpro. However, translating these in vitro findings into clinical applications remains challenging, especially due to insufficient cell permeability. [ABSTRACT FROM AUTHOR]

Materials with engineered nano‐scale surface topographies, such as nanopillars, nanoneedles, and nanowires, mimic natural structures like viral spike proteins, enabling them to bypass biological barriers like the plasma membrane. These properties have led to applications in nanoelectronics for intracellular sensing and drug delivery platforms, some of which are already in clinical trials. Here, evidence is present that nanotopographic materials can induce transient openings in the nuclear membranes of various cell types without penetrating the cells, breaching the nucleo‐cytoplasmic barrier, and allowing uncontrolled molecular exchange across the nuclear membrane. These openings, induced by nanoscale curvature, are temporary and repaired through the Endosomal Sorting Complexes Required for Transport (ESCRT)‐mediated mechanisms. The findings suggest a potential for nano\topographic materials to temporarily breach the nuclear membrane with potential applications in direct nuclear sensing and delivery. [ABSTRACT FROM AUTHOR]

H5N1, a highly pathogenic avian influenza virus, poses an ongoing and significant threat to global public health, primarily due to its potential to cause severe respiratory illness and high mortality rates in humans. Despite extensive efforts in vaccination and antiviral therapy, H5N1 continues to exhibit high mutation rates, resulting in recurrent outbreaks and the emergence of drug‐resistant strains. Traditional antiviral therapies, such as neuraminidase inhibitors and M2 ion channel blockers, have demonstrated limited efficacy, necessitating the exploration of innovative therapeutic strategies. Proteolysis‐targeting chimeras (PROTACs) emerge as a novel and promising approach, leveraging the ubiquitin‐proteasome system to selectively degrade pathogenic proteins. Unlike conventional inhibitors that only block protein function, PROTACs eliminate the target protein, providing a sustained therapeutic effect and potentially reducing the development of resistance. This paper offers a comprehensive examination of the current landscape of H5N1 infections, detailing the pathogenesis and challenges associated with existing treatments. It further explores the mechanism of action, design, and therapeutic potential of PROTACs in inhibiting H5N1. By targeting essential viral proteins, such as hemagglutinin and the RNA‐dependent RNA polymerase complex, PROTACs hold the potential to revolutionize the treatment of H5N1 infections, offering a new frontier in antiviral therapy. [ABSTRACT FROM AUTHOR]

The ubiquitin‐proteasome system is frequently employed to degrade viral proteins, thereby inhibiting viral replication and pathogenicity. Through an analysis of the degradation kinetics of all the SARS‐CoV‐2 proteins, our study revealed rapid degradation of several proteins, particularly NSP5. Additionally, we identified FBXO22, an E3 ubiquitin ligase, as the primary regulator of NSP5 ubiquitination. Moreover, we validated the interaction between FBXO22 and NSP5, demonstrating that FBXO22‐mediated ubiquitination of NSP5 facilitated its recognition by the proteasome, leading to subsequent degradation. Specifically, FBXO22 catalyzed the formation of K48‐linked polyubiquitin chains on NSP5 at lysine residues 5 and 90. Knockdown of FBXO22 resulted in decreased NSP5 ubiquitination levels, increased stability, and enhanced ability to evade the host innate immune response. Notably, the protein level of FBXO22 were negatively correlated with SARS‐CoV‐2 load, highlighting its importance in inhibiting viral replication. This study elucidates the molecular mechanism by which FBXO22 mediates the degradation of NSP5 and underscores its critical role in limiting viral replication. The identification of FBXO22 as a regulator of NSP5 stability provides new insights and potential avenues for targeting NSP5 in antiviral strategies. [ABSTRACT FROM AUTHOR]

Enteroviral infection is a common cause of aseptic meningitis, herpangina, and hand, foot, and mouth disease in children. Limited data are available on the enteroviral subtypes associated with hospitalization for these conditions in Kazakhstan. We collected cerebrospinal fluid (CSF) and nasopharyngeal swabs (NSW) from children (N = 152, median age = 8 years) hospitalized with symptoms of aseptic meningitis (AM, N = 139) or herpangina (HA, N = 13) disease. We then genotyped enteroviral subtypes associated with AM (n = 50) and HA (n = 9) using next‐generation sequencing (NGS) on the viral protein 1 (VP1), followed up by whole‐genome sequencing of the isolated viral species. All identified EVs were species B EV, consisting of five echoviruses (E6, E9, E11, E21, and E25) and three coxsackieviruses (CVA9, CVB3, and CVB5) serotypes within the cohort. The most abundant EVs were CVA9 (38.5%), CVB5 (21.5%), and E6 (13.8%). Most HA samples (6/9) were genotyped with coxsackievirus CVA9, while AM was associated with a variety of both echovirus and coxsackievirus serotypes. The results suggest that coxsackievirus CVA9 may be the dominant serotype circulating in the HA population, while AM is more diverse in terms of circulating echovirus and coxsackievirus serotypes. Further studies are needed to determine the clinical implications of these findings and to investigate potential differences in disease severity or outcomes associated with different EV serotypes. [ABSTRACT FROM AUTHOR]

Summary: IRE1, BI‐1, and bZIP60 monitor compatible plant–potexvirus interactions though recognition of the viral TGB3 protein. This study was undertaken to elucidate the roles of three IRE1 isoforms, the bZIP60U and bZIP60S, and BI‐1 roles in genetic reprogramming of cells during potexvirus infection.Experiments were performed using Arabidopsis thaliana knockout lines and Plantago asiatica mosaic virus infectious clone tagged with the green fluorescent protein gene (PlAMV‐GFP).There were more PlAMV‐GFP infection foci in ire1a/b, ire1c, bzip60, and bi‐1 knockout than wild‐type (WT) plants. Cell‐to‐cell movement and systemic RNA levels were greater bzip60 and bi‐1 than in WT plants. Overall, these data indicate an increased susceptibility to virus infection. Transgenic overexpression of AtIRE1b or StbZIP60 in ire1a/b or bzip60 mutant background reduced virus infection foci, while StbZIP60 expression influences virus movement. Transgenic overexpression of StbZIP60 also confers endoplasmic reticulum (ER) stress resistance following tunicamycin treatment. We also show bZIP60U and TGB3 interact at the ER.This is the first demonstration of a potato bZIP transcription factor complementing genetic defects in Arabidopsis. Evidence indicates that the three IRE1 isoforms regulate the initial stages of virus replication and gene expression, while bZIP60 and BI‐1 contribute separately to virus cell‐to‐cell and systemic movement. [ABSTRACT FROM AUTHOR]

Slowing down translocation dynamics is a crucial challenge in nanopore sensing of small molecules and particles. Here, it is reported on nanoparticle motion‐mediated local viscosity enhancement of water‐organic mixtures in a nanofluidic channel that enables slow translocation speed, enhanced capture efficiency, and improved signal‐to‐noise ratio by transmembrane voltage control. It is found that higher detection rates of nanoparticles under larger electrophoretic voltage in the highly viscous solvents. Meanwhile, the strongly pulled particles distort the liquid in the pore at high shear rates over 103 s−1 which leads to a counterintuitive phenomenon of slower translocation speed under higher voltage via the induced dilatant viscosity behavior. This mechanism is demonstrated as feasible with a variety of organic molecules, including glycerol, xanthan gum, and polyethylene glycol. The present findings can be useful in resistive pulse analyses of nanoscale objects such as viruses and proteins by allowing a simple and effective way for translocation slowdown, improved detection throughput, and enhanced signal‐to‐noise ratio. [ABSTRACT FROM AUTHOR]

Summary: Potassium (K+) plays a crucial role as a macronutrient in the growth and development of plants. Studies have definitely determined the vital roles of K+ in response to pathogen invasion. Our previous investigations revealed that rice plants infected with rice grassy stunt virus (RGSV) displayed a reduction in K+ content, but the mechanism by which RGSV infection subverts K+ uptake remains unknown. In this study, we found that overexpression of RGSV P1, a specific viral protein encoded by viral RNA1, results in enhanced sensitivity to low K+ stress and exhibits a significantly lower rate of K+ influx compared to wild‐type rice plants. Further investigation revealed that RGSV P1 interacts with OsCIPK23, an upstream regulator of Shaker K+ channel OsAKT1. Moreover, we found that the P1 protein recruits the OsCIPK23 to the Cajal bodies (CBs). In vivo assays demonstrated that the P1 protein competitively binds to OsCIPK23 with both OsCBL1 and OsAKT1. In the nucleus, the P1 protein enhances the binding of OsCIPK23 to OsCoilin, a homologue of the signature protein of CBs in Arabidopsis, and facilitates their trafficking through these CB structures. Genetic analysis indicates that mutant in oscipk23 suppresses RGSV systemic infection. Conversely, osakt1 mutants exhibited increased sensitivity to RGSV infection. These findings suggest that RGSV P1 hinders the absorption of K+ in rice plants by recruiting the OsCIPK23 to the CB structures. This process potentially promotes virus systemic infection but comes at the expense of inhibiting OsAKT1 activity. [ABSTRACT FROM AUTHOR]

Summary: Eukaryotic translation initiation factors (eIFs) are important for mRNA translation but also pivotal for plant‐virus interaction. Most of these plant‐virus interactions were found between plant eIFs and the viral protein genome‐linked (VPg) of potyviruses. In case of lost interaction due to mutation or deletion of eIFs, the viral translation and subsequent replication within its host is negatively affected, resulting in a recessive resistance. Here we report the identification of the Beta vulgaris Bv‐eIF(iso)4E as a susceptibility factor towards the VPg‐carrying beet chlorosis virus (genus Polerovirus). Using yeast two‐hybrid and bimolecular fluorescence complementation assays, the physical interaction between Bv‐eIF(iso)4E and the putative BChV‐VPg was detected, while the VPg of the closely related beet mild yellowing virus (BMYV) was found to interact with the two isoforms Bv‐eIF4E and Bv‐eIF(iso)4E. These VPg‐eIF interactions within the polerovirus‐beet pathosystem were demonstrated to be highly specific, as single mutations within the predicted cap‐binding pocket of Bv‐eIF(iso)4E resulted in a loss of interaction. To investigate the suitability of eIFs as a resistance resource against beet infecting poleroviruses, B. vulgaris plants were genome edited by CRISPR/Cas9 resulting in knockouts of different eIFs. A simultaneous knockout of the identified BMYV‐interaction partners Bv‐eIF4E and Bv‐eIF(iso)4E was not achieved, but Bv‐eIF(iso)4EKO plants showed a significantly lowered BChV accumulation and decrease in infection rate from 100% to 28.86%, while no influence on BMYV accumulation was observed. Still, these observations support that eIFs are promising candidate genes for polerovirus resistance breeding in sugar beet. [ABSTRACT FROM AUTHOR]

The SARS‐CoV‐2 genome has been shown to be m6A methylated at several positions in vivo. Strikingly, a DRACH motif, the recognition motif for adenosine methylation, resides in the core of the transcriptional regulatory leader sequence (TRS−L) at position A74, which is highly conserved and essential for viral discontinuous transcription. Methylation at position A74 correlates with viral pathogenicity. Discontinuous transcription produces a set of subgenomic mRNAs that function as templates for translation of all structural and accessory proteins. A74 is base‐paired in the short stem‐loop structure 5'SL3 that opens during discontinuous transcription to form long‐range RNA‐RNA interactions with nascent (−)‐strand transcripts at complementary TRS‐body sequences. A74 can be methylated by the human METTL3/METTL14 complex in vitro. Here, we investigate its impact on the structural stability of 5'SL3 and the long‐range TRS‐leader:TRS‐body duplex formation necessary for synthesis of subgenomic mRNAs of all four viral structural proteins. Methylation uniformly destabilizes 5'SL3 and long‐range duplexes and alters their relative equilibrium populations, suggesting that the m6A74 modification acts as a regulator for the abundance of viral structural proteins due to this destabilization. [ABSTRACT FROM AUTHOR]

Calixarenes are displaying great potential for the development of new drug delivery systems, diagnostic imaging, biosensing devices and inhibitors of biological processes. In particular, calixarene derivatives are able to interact with many different enzymes and function as inhibitors. By screening of the potential drug target database (PDTD) with a reverse docking procedure, we identify and discuss a selection of 100 proteins that interact strongly with calix[4]arene. We also discover that leucine (23.5 %), isoleucine (11.3 %), phenylalanines (11.3 %) and valine (9.5 %) are the most frequent binding residues followed by hydrophobic cysteines and methionines and aromatic histidines, tyrosines and tryptophanes. Top binders are peroxisome proliferator‐activated receptors that already are targeted by commercial drugs, demonstrating the practical interest in calix[4]arene. Nuclear receptors, potassium channel, several carrier proteins, a variety of cancer‐related proteins and viral proteins are prominent in the list. It is concluded that calix[4]arene, which is characterized by facile access, well‐defined conformational characteristics, and ease of functionalization at both the lower and higher rims, could be a potential lead compound for the development of enzyme inhibitors and theranostic platforms. [ABSTRACT FROM AUTHOR]

Autographa californica multiple nucleopolyhedrovirus (AcMNPV) is an enveloped DNA virus of the Baculoviridae family. This baculovirus is widely exploited for the biological control of insect pest species and as an expression platform to produce recombinant proteins in insect cells. Extracellular vesicles (EVs) are secreted by all cells and are involved in key roles in many biological processes through their cargo consisting of proteins, RNA or DNA. In viral infections, EVs have been found to transfer both viral and cellular cargo that can elicit either a pro‐ or antiviral response in recipient cells. Here, small EVs (sEVs) released by Spodoptera frugiperda (Sf) insect cells were characterised for the first time. Using S. frugiperda (SfC1B5) cells stably expressing the baculovirus gp64, the viral envelope protein GP64 was shown to be incorporated into sEVs. Sf9 cells were also transfected with a bacmid AcMNPV genome lacking p6.9 (AcΔP6.9) to prevent budded virus production. The protein content of sEVs from both mock‐ and AcΔP6.9‐transfected cells were analysed by mass spectrometry. In addition to GP64, viral proteins Ac‐F, ME‐53 and viral ubiquitin were identified, as well as many host proteins including TSG101—which may be useful as a protein marker for sEVs. [ABSTRACT FROM AUTHOR]

Summary: In maize, two pyruvate orthophosphate dikinase (PPDK) regulatory proteins, ZmPDRP1 and ZmPDRP2, are respectively specific to the chloroplast of mesophyll cells (MCs) and bundle sheath cells (BSCs). Functionally, ZmPDRP1/2 catalyse both phosphorylation/inactivation and dephosphorylation/activation of ZmPPDK, which is implicated as a major rate‐limiting enzyme in C4 photosynthesis of maize. Our study here showed that maize plants lacking ZmPDRP1 or silencing of ZmPDRP1/2 confer resistance to a prevalent potyvirus sugarcane mosaic virus (SCMV). We verified that the C‐terminal domain (CTD) of ZmPDRP1 plays a key role in promoting viral infection while independent of enzyme activity. Intriguingly, ZmPDRP1 and ZmPDRP2 re‐localize to cytoplasmic viral replication complexes (VRCs) following SCMV infection. We identified that SCMV‐encoded cytoplasmic inclusions protein CI targets directly ZmPDRP1 or ZmPDRP2 or their CTDs, leading to their re‐localization to cytoplasmic VRCs. Moreover, we found that CI could be degraded by the 26S proteasome system, while ZmPDRP1 and ZmPDRP2 could up‐regulate the accumulation level of CI through their CTDs by a yet unknown mechanism. Most importantly, with genetic, cell biological and biochemical approaches, we provide evidence that BSCs‐specific ZmPDRP2 could accumulate in MCs of Zmpdrp1 knockout (KO) lines, revealing a unique regulatory mechanism crossing different cell types to maintain balanced ZmPPDK phosphorylation, thereby to keep maize normal growth. Together, our findings uncover the genetic link of the two cell‐specific maize PDRPs, both of which are co‐opted to VRCs to promote viral protein accumulation for robust virus infection. [ABSTRACT FROM AUTHOR]

A virus discovery investigation using high‐throughput sequencing in sugarcane samples from Ethiopia revealed the presence of sugarcane mild mosaic virus (SCMMV, genus Ampelovirus) and sugarcane umbra‐like virus (SULV, genus Umbravirus). The genome sequences of two isolates of SCMMV and one SULV were determined. The sequences of the two SCMMV isolates were 13,005 nucleotides in length and showed ~73.5% nucleotide identity along the genome and ~90.2, 96.8, and 90.4% amino acid sequence identity among each other in the RdRp, CP, and HSP70h, respectively. Isolate SCMMV ET2 showed a close relationship to group A isolates from Colombia, the USA, and the Philippines, with amino acid sequence identity of the predicted virus proteins in the range of 94–98.9%. Conversely, SCMMV ET1 shared a closer relationship with group B isolates from Colombia, Ivory Coast, and Argentina, exhibiting a 93–99% amino acid sequence identity. The complete genome sequence of SULV, comprising 3041 nucleotides, exhibited the highest identity with its counterpart from South Africa (MN868593). These findings contribute to expanding our understanding of the viral diversity within the sugarcane crop in Ethiopia. [ABSTRACT FROM AUTHOR]

Vicinal oxygen chelate (VOC) proteins are members of an enzyme superfamily with dioxygenase or non‐dioxygenase activities. However, the biological functions of VOC proteins in plants are poorly understood. Here, we show that a VOC in Nicotiana benthamiana (NbVOC1) facilitates viral infection. NbVOC1 was significantly induced by infection by beet necrotic yellow vein virus (BNYVV). Transient overexpression of NbVOC1 or its homolog from Beta vulgaris (BvVOC1) enhanced BNYVV infection in N. benthamiana, which required the nuclear localization of VOC1. Consistent with this result, overexpressing NbVOC1 facilitated BNYVV infection, whereas, knockdown and knockout of NbVOC1 inhibited BNYVV infection in transgenic N. benthamiana plants. NbVOC1 interacts with the basic leucine zipper transcription factors bZIP17/28, which enhances their self‐interaction and DNA binding to the promoters of unfolded protein response (UPR)‐related genes. We propose that bZIP17/28 directly binds to the NbVOC1 promoter and induces its transcription, forming a positive feedback loop to induce the UPR and facilitating BNYVV infection. Collectively, our results demonstrate that NbVOC1 positively regulates the UPR that enhances viral infection in plants. [ABSTRACT FROM AUTHOR]

Background: SARS‐CoV2 virus, responsible for the COVID‐19 pandemic, has four structural proteins and 16 nonstructural proteins. S‐protein is one of the structural proteins exposed on the virus surface and is the main target for producing neutralizing antibodies and vaccines. The S‐protein forms a trimer that can bind the angiotensin‐converting enzyme 2 (ACE2) through its receptor binding domain (RBD) for cell entry. Aims: The goal of this study was to express in HEK293 cells a new RBD recombinant protein in a constitutive and stable manner in order to use it as an alternative immunogen and diagnostic tool for COVID‐19. Materials & Methods: The protein was designed to contain an immunoglobulin signal sequence, an explanded C‐terminal section of the RBD, a region responsible for the bacteriophage T4 trimerization inducer, and six histidines in the pCDNA‐3.1 plasmid. Following transformation, the cells were selected with geneticin‐G418 and purified from serum‐fre culture supernatants using Ni2+‐agarand size exclusion chromatography. The protein was structurally identified by cross‐linking and circular dichroism experiments, and utilized to immunize mice in conjuction with AS03 or alum adjuvants. The mice sera were examined for antibody recognition, receptor‐binding inhibition, and virus neutralization, while spleens were evaluated for γ‐interferon production in the presence of RBD. Results: The protein released in the culture supernatant of cells, and exhibited a molecular mass of 135 kDa with a secondary structure like the monomeric and trimeric RBD. After purification, it formed a multimeric structure comprising trimers and hexamers, which were able to bind the ACE2 receptor. It generated high antibody titers in mice when combined with AS03 adjuvant (up to 1:50,000). The sera were capable of inhibiting binding of biotin‐labeled ACE2 to the virus S1 subunit and could neutralize the entry of the Wuhan virus strain into cells at dilutions up to 1:2000. It produced specific IFN‐γ producing cells in immunized mouse splenocytes. Discussion: Our data describe a new RBD containing protein, forming trimers and hexamers, which are able to induce a protective humoral and cellular response against SARS‐CoV2. Conclusion: These results add a new arsenal to combat COVID‐19, as an alternative immunogen or antigen for diagnosis. [ABSTRACT FROM AUTHOR]

Extracellular vesicles (EVs) serve as pivotal mediators of intercellular communication in both health and disease, delivering biologically active molecules from vesicle‐producing cells to recipient cells. In the context of HIV infection, EVs have been shown to carry the viral protein Nef, a key pathogenic factor associated with HIV‐related co‐morbidities. Despite this recognition, the specific localisation of Nef within the vesicles has remained elusive. This study addresses this critical knowledge gap by investigating Nef‐containing EVs. Less than 1% of the total released Nef was associated with EVs; most Nef existed as free protein released by damaged cells. Nevertheless, activity of EV‐associated Nef in downregulating the major cholesterol transporter ABCA1, a critical aspect linked to the pathogenic effects of Nef, was comparable to that of free Nef present in the supernatant. Through a series of biochemical and microscopic assays, we demonstrate that the majority of EV‐associated Nef molecules are localised on the external surface of the vesicles. This distinctive distribution prompts the consideration of Nef‐containing EVs as potential targets for immunotherapeutic interventions aimed at preventing or treating HIV‐associated co‐morbidities. In conclusion, our results shed light on the localisation and functional activity of Nef within EVs, providing valuable insights for the development of targeted immunotherapies to mitigate the impact of HIV‐associated co‐morbidities. [ABSTRACT FROM AUTHOR]

Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) is the largest single‐stranded RNA virus known to date. Its genome contains multiple accessory protein genes that act against host immune responses but are not required for progeny virus production. The functions of the accessory proteins in the viral life cycle have been examined, but their involvement in viral pathogenicity remains unclear. Here, we investigated the roles of the accessory proteins in viral immunopathogenicity. To this end, recombinant SARS‐CoV‐2 possessing nonsense mutations in the seven accessory protein open reading frames (ORFs) (ORF3a, ORF3b, ORF6, ORF7a, ORF8, ORF9b, and ORF10) was de novo generated using an early pandemic SARS‐CoV‐2 strain as a backbone. We confirmed that the resultant virus (termed ORF3–10 KO) did not express accessory proteins in infected cells and retained the desired mutations in the viral genome. In cell culture, the ORF3–10 KO virus exhibited similar virus growth kinetics as the parental virus. In hamsters, ORF3–10 KO virus infection resulted in mild weight loss and reduced viral replication in the oral cavity and lung tissue. ORF3–10 KO virus infection led to mild inflammation, indicating that an inability to evade innate immune sensing because of a lack of accessory proteins impairs virus growth in vivo and results in quick elimination from the body. Overall, we showed that SARS‐CoV‐2 accessory proteins are involved in immunopathogenicity. [ABSTRACT FROM AUTHOR]

Background: This article explored the possibility that the Mpox virus (MPXV) may initiate or stimulate the consequences of vascular inflammation. In 1970, it was discovered that Macaca cynomolgus primates infected with MPXV also infected humans in the Democratic Republic of the Congo. Discussion: The study demonstrates that MPXV invades host cells via viral proteins and surface receptors, initiating the release of diverse inflammatory mediators such as IL‐1, IL‐6, TNF‐α, CCL2, CXCL2, CXCL8, CXCL10, and so forth probably through endothelial dysfunction by reactive oxygen species production. In general, these mediators have been found to contribute to vascular inflammation and the formation of atherosclerotic plaque at a later stage, which may contribute to the onset of vascular inflammation. Conclusion: The discussed association between vascular inflammation and Mpox has the potential to be an important finding in the field of vascular biology research. [ABSTRACT FROM AUTHOR]

Minute virus of canines (MVC) belongs to the genus Bocaparvovirus (formerly Bocavirus) within the Parvoviridae family and causes serious respiratory and gastrointestinal symptoms in neonatal canines worldwide. A productive viral infection relies on the successful recruitment of host factors for various stages of the viral life cycle. However, little is known about the MVC‐host cell interactions. In this study, we identified that two cellular proteins (Hsc70 and Hsp70) interacted with NS1 and VP2 proteins of MVC, and both two domains of Hsc70/Hsp70 were mediated for their interactions. Functional studies revealed that Hsp70 was induced by MVC infection, knockdown of Hsc70 considerably suppressed MVC replication, whereas the replication was dramatically promoted by Hsp70 knockdown. It is interesting that low amounts of overexpressed Hsp70 enhanced viral protein expression and virus production, but high amounts of Hsp70 overexpression weakened them. Upon Hsp70 overexpressing, we observed that the ubiquitination of viral proteins changed with Hsp70 overexpression, and proteasome inhibitor (MG132) restored an accumulation of viral proteins. In addition, we verified that Hsp70 family inhibitors remarkably decreased MVC replication. Overall, we identified Hsc70 and Hsp70 as interactors of MVC NS1 and VP2 proteins and were involved in MVC replication, which may provide novel targets for anti‐MVC approach. [ABSTRACT FROM AUTHOR]