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The biochemical interactions during coronavirus (CoV) replication and transcription and the CoV-host interactions are examined. The infection by different CoVs causes alterations in the transcription and translation patterns, cell cycle, cytoskeleton and apoptosis and coagulation pathways of the host cell, while the requirement for base pairing during transcription is demonstrated in arteriviruses and CoVs.

Zika virus (ZIKV) infection is currently one of the major concerns in human public health due to its association with neurological disorders. Intensive effort has been implemented for the treatment of ZIKV, however there are not currently approved vaccines or antivirals available to combat ZIKV infection. In this sense, the identification of virulence factors associated with changes in ZIKV virulence could help to develop safe and effective countermeasures to treat ZIKV or to prevent future outbreaks. Here, we have compared the virulence of two related ZIKV strains from the recent outbreak in Brazil (2015), Rio Grande do Norte Natal (RGN) and Paraiba. In spite of both viruses being identified in the same period of time and region, significant differences in virulence and replication were observed using a validated mouse model of ZIKV infection. While ZIKV-RGN has a 50% mouse lethal dose (MLD50) of ~105 focus forming units (FFUs), ZIKV-Paraiba infection resulted in 100% of lethality with less than 10 FFUs. Combining deep-sequencing analysis and our previously described infectious ZIKV-RGN cDNA clone, we identified a natural polymorphism in the non-structural protein 2 A (NS2A) that increase the virulence of ZIKV. Moreover, results demonstrate that the single amino acid alanine to valine substitution at position 117 (A117V) in the NS2A was sufficient to convert the attenuated rZIKV-RGN in a virulent Paraiba-like virus (MLD50 < 10 FFU). The mechanism of action was also evaluated and data indicate that substitution A117V in ZIKV NS2A protein reduces host innate immune responses and viral-induced apoptosis in vitro. Therefore, amino acid substitution A117V in ZIKV NS2A could be used as a genetic risk-assessment marker for future ZIKV outbreaks. [ABSTRACT FROM AUTHOR]

In order to gain insight into the role of the transcription regulatory sequences (TRSs) in the regulation of gene expression and replication of porcine reproductive and respiratory syndrome virus (PRRSV), the enhanced green fluorescent protein (EGFP) gene, under the control of the different structural gene TRSs, was inserted between the N gene and 3'-UTR of the PRRSV genome and EGFP expression was analyzed for each TRS. TRSs of all the studied structural genes of PRRSV positively modulated EGFP expression at different levels. Among the TRSs analyzed, those of GP2, GP5, M, and N genes highly enhanced EGFP expression without altering replication of PRRSV. These data indicated that structural gene TRSs could be an extremely useful tool for foreign gene expression using PRRSV as a vector. [ABSTRACT FROM AUTHOR]

An array comprising four Si $\mu $ -cantilevers coated with nanoporous functionalized ETS-10 crystals sub-micrometric in size has been developed as a multisensing platform for explosives recognition in vapor phase. The detection capabilities of the proposed device have been tested for common taggants [such as 1-methyl-2-nitro-benzene (o-MNT)] and explosives (commercial detonation cord, a plastic tube filled with pentaerythritol tetranitrate (PETN); and C-4, a mixture of cyclotrimethylenetrinitramine (RDX), binders and plastifiers). The general strategy for the detection of explosives in vapor phase is based on the characteristic fingerprint each one produces as a result of the dissimilar chemical interactions between the ETS-10 coated $\mu $ -cantilevers and the target molecules emanating from the explosives and swept by ambient air. A portable lock-in amplifier has been implemented to exploit the truly benefits of the array in terms of portability, reduced size, and energy consumption. Such low-power electronic interface is capable of creating the excitation signal as well as obtaining the response values of four resonating $\mu $ -cantilevers simultaneously. The resulting sensing platform has successfully been applied for the o-MNT, PETN, and RDX detection at trace level. [ABSTRACT FROM PUBLISHER]

Most of the ac–ac converters used in home appliances are based on single-output dc-link inverters, which provide a cost-effective and straightforward solution. However, a two-stage power conversion decreases power density and efficiency. A direct ac–ac conversion has been thoroughly studied in the past. Nevertheless, the complex control scheme and higher cost have prevented it from being used in cost-oriented applications, such as home appliances. This paper proposes a direct ac–ac conversion scheme by means of a multiple-output resonant matrix converter applied to multiple inductive load systems. The proposed topology reduces significantly the number of devices and complexity, leading to an efficient, versatile, and cost-effective solution. The analytical and simulation results have been verified by means of a prototype applied to a novel total-active-surface induction-heating appliance. [ABSTRACT FROM AUTHOR]

Zika virus (ZIKV) was identified in 1947 in the Zika forest of Uganda and it has emerged recently as a global health threat, with recurring outbreaks and its associations with congenital microcephaly through maternal fetal transmission and Guillain-Barré syndrome. Currently, there are no United States (US) Food and Drug Administration (FDA)-approved vaccines or antivirals to treat ZIKV infections, which underscores an urgent medical need for the development of disease intervention strategies to treat ZIKV infection and associated disease. Drug repurposing offers various advantages over developing an entirely new drug by significantly reducing the timeline and resources required to advance a candidate antiviral into the clinic. Screening the ReFRAME library, we identified ten compounds with antiviral activity against the prototypic mammarenavirus lymphocytic choriomeningitis virus (LCMV). Moreover, we showed the ability of these ten compounds to inhibit influenza A and B virus infections, supporting their broad-spectrum antiviral activity. In this study, we further evaluated the broad-spectrum antiviral activity of the ten identified compounds by testing their activity against ZIKV. Among the ten compounds, Azaribine (SI-MTT = 146.29), AVN-944 (SI-MTT = 278.16), and Brequinar (SI-MTT = 157.42) showed potent anti-ZIKV activity in post-treatment therapeutic conditions. We also observed potent anti-ZIKV activity for Mycophenolate mofetil (SI-MTT = 20.51), Mycophenolic acid (SI-MTT = 36.33), and AVN-944 (SI-MTT = 24.51) in pre-treatment prophylactic conditions and potent co-treatment inhibitory activity for Obatoclax (SI-MTT = 60.58), Azaribine (SI-MTT = 91.51), and Mycophenolate mofetil (SI-MTT = 73.26) in co-treatment conditions. Importantly, the inhibitory effect of these compounds was strain independent, as they similarly inhibited ZIKV strains from both African and Asian/American lineages. Our results support the broad-spectrum antiviral activity of these ten compounds and suggest their use for the development of antiviral treatment options of ZIKV infection. [ABSTRACT FROM AUTHOR]

Serine incorporator protein 5 (SERINC5) is a key innate immunity factor that operates in the cell to restrict the infectivity of certain viruses. Different viruses have developed strategies to antagonize SERINC5 function but, how SERINC5 is controlled during viral infection is poorly understood. Here, we report that SERINC5 levels are reduced in COVID-19 patients during the infection by SARS-CoV-2 and, since no viral protein capable of repressing the expression of SERINC5 has been identified, we hypothesized that SARS-CoV-2 non-coding small viral RNAs (svRNAs) could be responsible for this repression. Two newly identified svRNAs with predicted binding sites in the 3'-untranslated region (3'-UTR) of the SERINC5 gene were characterized and we found that the expression of both svRNAs during the infection was not dependent on the miRNA pathway proteins Dicer and Argonaute-2. By using svRNAs mimic oligonucleotides, we demonstrated that both viral svRNAs can bind the 3'UTR of SERINC5 mRNA, reducing SERINC5 expression in vitro . Moreover, we found that an anti-svRNA treatment to Vero E6 cells before SARS-CoV-2 infection recovered the levels of SERINC5 and reduced the levels of N and S viral proteins. Finally, we showed that SERINC5 positively controls the levels of Mitochondrial Antiviral Signalling (MAVS) protein in Vero E6. These results highlight the therapeutic potential of targeting svRNAs based on their action on key proteins of the innate immune response during SARS-CoV-2 viral infection., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Meseguer, Rubio, Lainez, Pérez-Benavente, Pérez-Moraga, Romera-Giner, García-García, Martinez-Macias, Cremades, Iborra, Candelas-Rivera, Almazan and Esplugues.)

Infectious coronavirus (CoV) disease 2019 (COVID-19) emerged in the city of Wuhan (China) in December 2019, causing a pandemic that has dramatically impacted public health and socioeconomic activities worldwide. A previously unknown coronavirus, severe acute respiratory syndrome CoV-2 (SARS-CoV-2), has been identified as the causative agent of COVID-19. To date, there are no U.S. Food and Drug Administration (FDA)-approved vaccines or therapeutics available for the prevention or treatment of SARS-CoV-2 infection and/or associated COVID-19 disease, which has triggered a large influx of scientific efforts to develop countermeasures to control SARS-CoV-2 spread. To contribute to these efforts, we have developed an infectious cDNA clone of the SARS-CoV-2 USA-WA1/2020 strain based on the use of a bacterial artificial chromosome (BAC). Recombinant SARS-CoV-2 (rSARS-CoV-2) was readily rescued by transfection of the BAC into Vero E6 cells. Importantly, BAC-derived rSARS-CoV-2 exhibited growth properties and plaque sizes in cultured cells comparable to those of the natural SARS-CoV-2 isolate. Likewise, rSARS-CoV-2 showed levels of replication similar to those of the natural isolate in nasal turbinates and lungs of infected golden Syrian hamsters. This is, to our knowledge, the first BAC-based reverse genetics system for the generation of infectious rSARS-CoV-2 that displays features in vivo similar to those of a natural viral isolate. This SARS-CoV-2 BAC-based reverse genetics will facilitate studies addressing several important questions in the biology of SARS-CoV-2, as well as the identification of antivirals and development of vaccines for the treatment of SARS-CoV-2 infection and associated COVID-19 disease. IMPORTANCE The pandemic coronavirus (CoV) disease 2019 (COVID-19) caused by severe acute respiratory syndrome CoV-2 (SARS-CoV-2) is a major threat to global human health. To date, there are no approved prophylactics or therapeutics available for COVID-19. Reverse genetics is a powerful approach to understand factors involved in viral pathogenesis, antiviral screening, and vaccine development. In this study, we describe the feasibility of generating recombinant SARS-CoV-2 (rSARS-CoV-2) by transfection of a single bacterial artificial chromosome (BAC). Importantly, rSARS-CoV-2 possesses the same phenotype as the natural isolate in vitro and in vivo This is the first description of a BAC-based reverse genetics system for SARS-CoV-2 and the first time that an rSARS-CoV-2 isolate has been shown to be phenotypically identical to a natural isolate in a validated animal model of SARS-CoV-2 infection. The BAC-based reverse genetics approach will facilitate the study of SARS-CoV-2 and the development of prophylactics and therapeutics for the treatment of COVID-19., (Copyright © 2020 Ye et al.)

After publication of the article [1], it has been brought to our attention that an acknowledgement has been omitted from the original article. The authors would like to include the following, The authors also thank Prof. En-Min Zhou (Northwest A&F University) and his laboratory for technical support."

In order to gain insight into the role of the transcription regulatory sequences (TRSs) in the regulation of gene expression and replication of porcine reproductive and respiratory syndrome virus (PRRSV), the enhanced green fluorescent protein (EGFP) gene, under the control of the different structural gene TRSs, was inserted between the N gene and 3'-UTR of the PRRSV genome and EGFP expression was analyzed for each TRS. TRSs of all the studied structural genes of PRRSV positively modulated EGFP expression at different levels. Among the TRSs analyzed, those of GP2, GP5, M, and N genes highly enhanced EGFP expression without altering replication of PRRSV. These data indicated that structural gene TRSs could be an extremely useful tool for foreign gene expression using PRRSV as a vector.

Here we report the rescue of a recombinant porcine reproductive and respiratory syndrome virus (PRRSV) carrying an enhanced green fluorescent protein (EGFP) reporter gene as a separate transcription unit. A copy of the transcription regulatory sequence for ORF6 (TRS6) was inserted between the N protein and 3'-UTR to drive the transcription of the EGFP gene and yield a general purpose expression vector. Successful recovery of PRRSV was obtained using an RNA polymerase II promoter to drive transcription of the full-length virus genome, which was assembled in a bacterial artificial chromosome (BAC). The recombinant virus showed growth replication characteristics similar to those of the wild-type virus in the infected cells. In addition, the recombinant virus stably expressed EGFP for at least 10 passages. EGFP expression was detected at approximately 10 h post infection by live-cell imaging to follow the virus spread in real time and the infection of neighbouring cells occurred predominantly through cell-to-cell-contact. Finally, the recombinant virus generated was found to be an excellent tool for neutralising antibodies and antiviral compound screening. The newly established reverse genetics system for PRRSV could be a useful tool not only to monitor virus spread and screen for neutralising antibodies and antiviral compounds, but also for fundamental research on the biology of the virus.