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COVID-19: Corticosteroids counteract inflammation by interferon The ability of corticosteroid drugs to alleviate extreme inflammation in severe cases of COVID-19 is linked to their reduction of the gene expression that is stimulated by interferon, an immunological cytokine protein. Interferon is crucial for a healthy immune response, but when produced in excess it can play a central role in causing damaging inflammation. Hyun-Woo Jeong at the Max Planck Institute for Molecular Biomedicine, Münster, Germany, and colleagues in South Korea compared the activity of genes involved in the inflammatory response in blood cells from COVID-19 patients and healthy donors. The results provided insights into the role of altered gene activity in both aggravation and improvement of COVID-19. Of particular interest was the ability of corticosteroids to downregulate the activity of a gene called STAT1, involved in mediating interferon signals.

Abstract Although nearly a fifth of symptomatic COVID-19 patients suffers from severe pulmonary inflammation, the mechanism of developing severe illness is not yet fully understood. To identify significantly altered genes in severe COVID-19, we generated messenger RNA and micro-RNA profiling data of peripheral blood mononuclear cells (PBMCs) from five COVID-19 patients (2 severe and 3 mild patients) and three healthy controls (HC). For further evaluation, two publicly available RNA-Seq datasets (GSE157103 and GSE152418) and one single-cell RNA-Seq dataset (GSE174072) were employed. Based on RNA-Seq datasets, thrombospondin 1 (THBS1) and interleukin-17 receptor A (IL17RA) were significantly upregulated in severe COVID-19 patients’ blood. From single-cell RNA-sequencing data, IL17RA level is increased in monocytes and neutrophils, whereas THBS1 level is mainly increased in the platelets. Moreover, we identified three differentially expressed microRNAs in severe COVID-19 using micro-RNA sequencings. Intriguingly, hsa-miR-29a-3p significantly downregulated in severe COVID-19 was predicted to bind the 3′-untranslated regions of both IL17RA and THBS1 mRNAs. Further validation analysis of our cohort (8 HC, 7 severe and 8 mild patients) showed that THBS1, but not IL17RA, was significantly upregulated, whereas hsa-miR-29a-3p was downregulated, in PBMCs from severe patients. These findings strongly suggest that dysregulated expression of THBS1, IL17RA, and hsa-miR-29a-3p involves severe COVID-19.

ABSTRACT: Objectives: The socioeconomic and clinical burden of multidrug-resistant organisms (MDRO), including methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), multidrug-resistant Acinetobacter baumannii (MRAB), multidrug-resistant Pseudomonas aeruginosa (MRPA), and carbapenem-resistant Enterobacteriaceae (CRE) have not yet been adequately addressed. Methods: We prospectively searched for MDRO bacteremia cases with matched controls from 10 hospitals across Korea during a 6-month period in 2017. Patients were classified into the MDRO, susceptible organism, and no-infection groups. The corresponding susceptible or no-infection controls had been selected according to predefined criteria. We collected clinical information and estimated the total additional medical cost due to MDRO infections using the multistate model. Results: During the 6-month period, a total of 486 MDRO bacteremia cases (260, 87, 18, 20, and 101 cases of MRSA, MRAB, MRPA, CRE, and VRE, respectively) were identified. The 90-d mortality rates were 30.4%, 63.2%, 16.7%, 55.0%, and 47.5%, respectively. The additional costs caused by bacteremia were $15 768, $35 682, $39 908, $72 051, and $33 662 per MDRO type, respectively. Based on these 6-month data, the estimated annual number of bacteremia cases due to these five MDRO in Korea were 7979 (4070, 1396, 218, 461, and 1834 cases, respectively). Overall, this caused an estimated 3280 (1237, 882, 36, 254, and 871, respectively) deaths and cost $294 505 002 ($84 707 359, $74 387 364, $10 344 370, $45 850 215, and $79 215 694, respectively) (range $170,627,020–$416,094,679) in socioeconomic loss. Conclusions: A tremendous clinical and economic burden is caused by MDRO bacteremia compared with antibiotic-susceptible and no-infection groups. Substantial investment and efforts by related government agencies and medical staffs are needed.

Abstract We aimed to estimate the socioeconomic burden of pneumonia due to multidrug-resistant Acinetobacter baumannii (MRAB) and Pseudomonas aeruginosa (MRPA). We prospectively searched for MRAB and MRPA pneumonia cases and matched them with susceptible-organism pneumonia and non-infected patients from 10 hospitals. The matching criteria were: same principal diagnosis, same surgery or intervention during hospitalisation, age, sex, and admission date within 60 days. We calculated the economic burden by using the difference in hospital costs, the difference in caregiver costs, and the sum of productivity loss from an unexpected death. We identified 108 MRAB pneumonia [MRAB-P] and 28 MRPA pneumonia [MRPA-P] cases. The estimated number of annual MRAB-P and MRPA-P cases in South Korea were 1309–2483 and 339–644, with 485–920 and 133–253 deaths, respectively. The annual socioeconomic burden of MRAB-P and MRPA-P in South Korea was $64,549,723–122,533,585 and $15,241,883–28,994,008, respectively. The results revealed that MRAB-P and MRPA-P occurred in 1648–3127 patients, resulted in 618–1173 deaths, and caused a nationwide socioeconomic burden of $79,791,606–151,527,593. Multidrug-resistant organisms (MDRO) impose a great clinical and economic burden at a national level. Therefore, controlling the spread of MDRO will be an effective measure to reduce this burden.

Background/Aims Coronavirus disease 2019 (COVID-19) is associated with acute respiratory syndrome. The mechanisms underlying the different degrees of pneumonia severity in patients with COVID-19 remain elusive. This study provides evidence that COVID-19 is associated with eosinophil-mediated inflammation. Methods We performed a retrospective case series of three patients with laboratory and radiologically confirmed COVID-19 pneumonia admitted to Chosun University Hospital. Demographic and clinical data on inflammatory cell lung infiltration and cytokine levels in patients with COVID-19 were collected. Results Cytological analysis of sputum, tracheal aspirates, and bronchoalveolar lavage fluid (BALF) samples from all three patients revealed massive infiltration of polymorphonuclear cells (PMNs), such as eosinophils and neutrophils. All sputum and BALF specimens contained high levels of eosinophil cationic proteins. The infiltration of PMNs into the lungs, together with elevated levels of natural killer T (NKT) cells in BALF and peripheral blood samples from patients with severe pneumonia in the acute phase was confirmed by flow cytometry. Conclusions These results suggest that the lungs of COVID-19 patients can exhibit eosinophil-mediated inflammation, together with an elevated NKT cell response, which is associated with COVID-19 pneumonia.

IntroductionDespite of massive endeavors to characterize inflammation in COVID-19 patients, the core network of inflammatory mediators responsible for severe pneumonia stillremain remains elusive. MethodsHere, we performed quantitative and kinetic analysis of 191 inflammatory factors in 955 plasma samples from 80 normal controls (sample n = 80) and 347 confirmed COVID-19 pneumonia patients (sample n = 875), including 8 deceased patients. ResultsDifferential expression analysis showed that 76% of plasmaproteins (145 factors) were upregulated in severe COVID-19 patients comparedwith moderate patients, confirming overt inflammatory responses in severe COVID-19 pneumonia patients. Global correlation analysis of the plasma factorsrevealed two core inflammatory modules, core I and II, comprising mainly myeloid cell and lymphoid cell compartments, respectively, with enhanced impact in a severity-dependent manner. We observed elevated IFNA1 and suppressed IL12p40, presenting a robust inverse correlation in severe patients, which was strongly associated with persistent hyperinflammation in 8.3% of moderate pneumonia patients and 59.4% of severe patients. DiscussionAberrant persistence of pulmonary and systemic inflammation might be associated with long COVID-19 sequelae. Our comprehensive analysis of inflammatory mediators in plasmarevealed the complexity of pneumonic inflammation in COVID-19 patients anddefined critical modules responsible for severe pneumonic progression.

Many individuals are diagnosed with human immunodeficiency virus (HIV) infection at an advanced stage of illness and are considered late presenters. We define late presentation as a CD4 cell count below 350 cells/mm3 at the time of HIV diagnosis, or presenting with an AIDS-defining illness regardless of CD4 count. Across Asia, an estimated 34–72% of people diagnosed with HIV are late presenters. HIV late presenters generally have a higher disease burden and higher comorbidity such as opportunistic infections than those who are diagnosed earlier. They also have a higher mortality rate and generally exhibit poorer immune recovery following combined antiretroviral therapy (cART). As such, late HIV presentation leads to increased resource burden and costs to healthcare systems. HIV late presentation also poses an increased risk of community transmission since the transmission rate from people unaware of their HIV status is approximately 3.5 times higher than that of early presenters. There are several factors which contribute to HIV late presentation. Fear of stigmatisation and discrimination are significant barriers to both testing and accessing treatment. A lack of perceived risk and a lack of knowledge by individuals also contribute to late presentation. Lack of referral for testing by healthcare providers is another identified barrier in China and may extend to other regions across Asia. Effective strategies are still needed to reduce the incidence of late presentation across Asia. Key areas of focus should be increasing community awareness of the risk of HIV, reducing stigma and discrimination in testing, and educating healthcare professionals on the need for early testing and on the most effective ways to engage with people living with HIV. Recent initiatives such as intensified patient adherence support programs and HIV self-testing also have the potential to improve access to testing and reduce late diagnosis.

Abstract Dual-labeled PNA probe used RT-LAMP molecular rapid assay targeting SARS-CoV-2 ORF1ab and N genes was developed, and the analytical, clinical performances for detection of SARS-CoV-2 RNA extracted from clinical nasopharyngeal swab specimens were evaluated in this study. Data showed that this assay is highly specific for SARS-CoV-2, and the absolute detection limit is 1 genomic copy per microliter of viral RNA which can be considered to be comparable to gold-standard molecular diagnostic method real-time reverse transcriptase PCR. Both clinical sensitivity and specificity against a commercial real-time RT-PCR assay were determined as identical. In conclusion, the PNA RT-LAMP assay showed high analytical and clinical accuracy which are identical to real-time RT-PCR which has been routinely used for the detection of SARS-CoV-2.

Abstract It is highly important to sensitively measure the abundance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on various surfaces. Here, we present a nucleic acid-based detection method consisting of a new sample preparation protocol that isolates only viruses, not the free RNA fragments already present on the surfaces of indoor human-inhabited environments, using a graphene oxide-coated microbead filter. Wet wipes (100 cm2), not cotton swabs, were used to collect viruses from environmental surfaces with large areas, and viruses were concentrated and separated with a graphene oxide-coated microbead filter. Viral RNA from virus was recovered 88.10 ± 8.03% from the surface and free RNA fragment was removed by 99.75 ± 0.19% from the final eluted solution. When we tested the developed method under laboratory conditions, a 10-fold higher viral detection sensitivity (Detection limit: 1 pfu/100 cm2) than the current commercial protocol was observed. Using our new sample preparation protocol, we also confirmed that the virus was effectively removed from surfaces after chemical disinfection; we were unable to measure the disinfection efficiency using the current commercial protocol because it cannot distinguish between viral RNA and free RNA fragments. Finally, we investigated the presence of SARS-CoV-2 and bacteria in 12 individual negative pressure wards in which patients with SARS-CoV-2 infection had been hospitalized. Bacteria (based on 16 S DNA) were found in all samples collected from patient rooms; however, SARS-CoV-2 was mainly detected in rooms shared by two patients.

Summary: Despite the worldwide effect of the coronavirus disease 2019 (COVID-19) pandemic, the underlying mechanisms of fatal viral pneumonia remain elusive. Here, we show that critical COVID-19 is associated with enhanced eosinophil-mediated inflammation when compared to non-critical cases. In addition, we confirm increased T helper (Th)2-biased adaptive immune responses, accompanying overt complement activation, in the critical group. Moreover, enhanced antibody responses and complement activation are associated with disease pathogenesis as evidenced by formation of immune complexes and membrane attack complexes in airways and vasculature of lung biopsies from six fatal cases, as well as by enhanced hallmark gene set signatures of Fcγ receptor (FcγR) signaling and complement activation in myeloid cells of respiratory specimens from critical COVID-19 patients. These results suggest that SARS-CoV-2 infection may drive specific innate immune responses, including eosinophil-mediated inflammation, and subsequent pulmonary pathogenesis via enhanced Th2-biased immune responses, which might be crucial drivers of critical disease in COVID-19 patients.

The unexpectedly large outbreak of Middle East respiratory syndrome in South Korea in 2015 was initiated by an infected traveler and amplified by several “superspreading” events. Previously, we reported the emergence and spread of mutant Middle East respiratory syndrome coronavirus bearing spike mutations (I529T or D510G) with reduced affinity to human receptor CD26 during the outbreak. To assess the potential association of spike mutations with superspreading events, we collected virus genetic information reported during the outbreak and systemically analyzed the relationship of spike sequences and epidemiology. We found sequential emergence of the spike mutations in 2 superspreaders. In vivo virulence of the mutant viruses seems to decline in human patients, as assessed by fever duration in affected persons. In addition, neutralizing activity against these 2 mutant viruses in serum samples from mice immunized with wild-type spike antigen were gradually reduced, suggesting emergence and wide spread of neutralization escapers during the outbreak.

Background: The efficacy and safety of a single tablet regimen (STR) of elvitegravir/cobicistat/emtricitabine/tenofovir alafenamide (E/C/F/TAF) was analyzed in Phase 3 clinical trials in antiretroviral therapy (ART)-naive and ART-experienced Asian participants infected with human immunodeficiency virus (HIV)-1 through 96 or 144 weeks. Objective: In Asian population requiring treatment, it is imperative to have data specific to this group, particularly as there is a general concern that Asians with lower body weight have increased risk of tenofovir disoproxil fumarate (TDF)-related renal dysfunction. Methods: Studies -104 and 111 were randomized, double-blind, placebo-controlled, 144-week studies conducted in ART-naive participants, comparing E/C/F/TAF versus E/C/F/TDF. Study 109 was a randomized, open-label, 96-week study conducted in virologically suppressed, ART-experienced participants, who switched to E/C/F/TAF from ritonavir/cobicistat-boosted atazanavir ATV+(RTV or COBI) + F/TDF regimens, from non-nucleoside reverse transcriptase inhibitors (NNRTI) + F/TDF regimens, or from E/C/F/TDF. Study 112 was a single arm, open-label, 144-week study conducted in HIV suppressed, ART-experienced participants with mild-moderate renal impairment, who switched to E/C/F/TAF. Results: Asian participants in these studies had sustained efficacy safety and tolerability. In Study 104/111, Asian participants achieved 93% virologic suppression on TAF vs 88% on TDF at week 144. At baseline, there were numerically more Asians with median CD4 counts < 200 cells/uL and VL > 100,000 c/mL. In Study 109, 95% of Asians on TAF vs 86% on TDF maintained virologic suppression at week 96. Lastly, in Study 112, 91% maintained virologic suppression at week 144. There were no discontinuations due to renal AE, no cases of PRT or Fanconi syndrome in any of the studies.

Despite a clear association of patient’s age with COVID-19 severity, there has been conflicting data on the association of viral load with disease severity. Here, we investigated the association of viral load dynamics with patient’s age and severity of COVID-19 using a set of respiratory specimens longitudinally collected (mean: 4.8 times/patient) from 64 patients with broad distribution of clinical severity and age during acute phase. Higher viral burden was positively associated with inflammatory responses, as assessed by IL-6, C-reactive protein, and lactate dehydrogenase levels in patients’ plasma collected on the same day, primarily in the younger cohort (≤59 years old) and in mild cases of all ages, whereas these were barely detectable in elderly patients (≥60 years old) with critical disease. In addition, viral load dynamics in elderly patients were not significantly different between mild and critical cases, even though more enhanced inflammation was consistently observed in the elderly group when compared to the younger group during the acute phase of infection. The positive correlation of viral load with disease severity in younger patients may explain the increased therapeutic responsiveness to current antiviral drugs and neutralizing antibody therapies in younger patients compared to elderly patients. More careful intervention against aging-associated inflammation might be required to mitigate severe disease progression and reduce fatality in COVID-19 patients more than 60 years old.

Abstract Background Severe fever with thrombocytopenia syndrome (SFTS) is emerging in Asian 3 countries, China, Japan and Korea, which are scrub typhus endemic areas, and its incidence is increasing. As the two infections overlap epidemiologically and clinically and the accessibility or sensitivity of diagnostic tests is limited, early clinical prediction may be useful for diagnostic and therapeutic purposes. Methods Patients aged ≥16 years who were clinically suspected and laboratory-confirmed to be infected with Orientia tsutsugamushi or the SFTS virus in South Korea were enrolled. Clinical and laboratory parameters were compared. Scrub typhus was further subclassified according to the status of eschar and skin rash. An SFTS prediction scoring tool was generated based on a logistic regression analysis of SFTS compared with scrub typhus. Results The analysis was performed on 255 patients with scrub typhus and 107 patients with SFTS. At initial presentation, subjective symptoms except for gastrointestinal symptoms, were more prominent in scrub typhus patients. In addition to the characteristic eschar and skin rash, headache was significantly more prominent in scrub typhus, while laboratory abnormalities were more prominent in SFTS. Leukopenia (white blood cell count

Orientia tsutsugamushi infection can cause acute lung injury and high mortality in humans; however, the underlying mechanisms are unclear. Here, we tested a hypothesis that dysregulated pulmonary inflammation and Tie2-mediated endothelial malfunction contribute to lung damage. Using a murine model of lethal O. tsutsugamushi infection, we demonstrated pathological characteristics of vascular activation and tissue damage: 1) a significant increase of ICAM-1 and angiopoietin-2 (Ang2) proteins in inflamed tissues and lung-derived endothelial cells (EC), 2) a progressive loss of endothelial quiescent and junction proteins (Ang1, VE-cadherin/CD144, occuludin), and 3) a profound impairment of Tie2 receptor at the transcriptional and functional levels. In vitro infection of primary human EC cultures and serum Ang2 proteins in scrub typhus patients support our animal studies, implying endothelial dysfunction in severe scrub typhus. Flow cytometric analyses of lung-recovered cells further revealed that pulmonary macrophages (MΦ) were polarized toward an M1-like phenotype (CD80+CD64+CD11b+Ly6G-) during the onset of disease and prior to host death, which correlated with the significant loss of CD31+CD45- ECs and M2-like (CD206+CD64+CD11b+Ly6G-) cells. In vitro studies indicated extensive bacterial replication in M2-type, but not M1-type, MΦs, implying the protective and pathogenic roles of M1-skewed responses. This is the first detailed investigation of lung cellular immune responses during acute O. tsutsugamushi infection. It uncovers specific biomarkers for vascular dysfunction and M1-skewed inflammatory responses, highlighting future therapeutic research for the control of this neglected tropical disease.

Objectives: This study aimed to characterize the risk factors for mortality in adult patients with invasive pneumococcal disease (IPD) stratified by age groups, after implementation of the national immunization program of 23-valent polysaccharide vaccine (PPSV23) for those aged ≥65 years in the Republic of Korea (ROK). Methods: Clinical data and pneumococcal isolates from adult patients with IPD (≥18 years of age) were collected prospectively from 20 hospitals through the nationwide surveillance program from March 2013 to October 2015. Results: A total of 319 patients with IPD were enrolled. Median age was 69 years. Overall in-hospital mortality was 34.2%: 17.1% in those aged 18–49 years, 23.7% in those aged 50–64 years, 33.0% in those aged 65–74 years, and 51.0% in those aged ≥75 years (p

Background: The influenza B virus has two lineages; Yamagata and Victoria. The two lineages are antigenically distinct and it is difficult to expect cross-protection between the lineages. Actually, the mismatch between circulating influenza B viruses and vaccine strains has been occurred frequently. The cell-culture system for the production of influenza vaccine can contribute to improve vaccine strain selection and expand vaccine supplies. We investigated the immunogenicity and safety of cell culture-derived quadrivalent inactivated influenza vaccine (NBP607-QIV) in adults and elderly subjects. Methods: A randomized controlled phase III trial was undertaken in 10 university hospitals in the Republic of Korea (Clinical trial Number—NCT02467842). Adults (aged 19–59 years) and elderly subjects (aged ≥60 years) were randomly assigned in a 2:1:1 ratio to NBP607-QIV versus cell culture-based trivalent inactivated influenza vaccine-Yamagata (NBP607-Y) and cell culture-based trivalent inactivated influenza vaccine-Victoria (NBP607-V). Immunogenicity was assessed 3 weeks after vaccination by hemagglutination inhibition assay. Safety was assessed for 6 months post-vaccination: solicited adverse events (AEs) for 7 days, unsolicited AEs for 21 days and serious adverse events (SAEs) for 6 months. AEs were sub-classified as adverse drug reactions (ADRs) according to the causality. Results: A total of 1,503 participants were randomly assigned to NBP607-QIV (n = 752), NBP607-Y (n = 373) and NBP607-V (n = 378). The seroconversion rates of NBP607-QIV were 52.4%, 51.2%, 43.7% and 55.8% against A/H1N1, A/H3N2, B/Yamagata and B/Victoria, respectively. Non-inferiority against shared strains and superiority against alternate-lineage B strains were demonstrated for NBP607-QIV vs. NBP607-Y and NBP607-V. A total of 730 reactions occurred in 324 (43.1%) subjects of NBP607-QIV group. Majority of ADRs was solicited (99.2%) and mild (90.3%) in intensity. In adults (aged 19–59 years), solicited local AEs were slightly more frequent in NBP607-QIV group than NBP607-Y or NBP607-V group (40.9%, 33.4% and 32.5%, respectively). One SAE was observed among NBP607-QIV group, which was considered to be unrelated to the study vaccine within 3 weeks of vaccination and no vaccine-related SAEs were reported up to 6 months after vaccination. Conclusions: NBP607-QIV is a safe, well-tolerated and immunogenic influenza vaccine in Korean adults and elderly subjects.

Scrub typhus, caused by Orientia tsutsugamushi infection, has been a serious public health issue in the Asia-Pacific region, with rising incidence and sporadic outbreaks. However, human protective immunity against specific antigens has been poorly characterized for this bacterium. In addition, immunity produced in early vaccine trials or even after natural infections, did not last long and had poor cross-reactivity among various genotypes. Here, we systematically investigated the kinetics and magnitude of specific adaptive immunity against two membrane antigens, 56 kDa type-specific antigen (TSA56) and surface cell antigen A (ScaA), that are involved in bacterial adhesion and invasion of the host in 64 recovered scrub typhus patients. Antibody responses to the bacterial antigens in patients were generally short-lived and waned to baseline levels 2 years after recovery. The anti-TSA56 IgG responses were predominantly composed of the IgG1 and IgG3 subclasses and persisted for up to 1 year after recovery, whereas IgG specific to ScaA primarily consisted of more transient IgG1, with limited responses by other subclasses. Cellular immunity, including CD4 and CD8 T-cells specific to membrane antigens, also rapidly declined from 1 year after infection, as measured by enzyme-linked immunospot (ELISPOT) assays and flow cytometry. The short longevity of antigen-specific adaptive immunity might be attributable to limited memory responses, as observed in earlier vaccine studies using whole bacterial antigens. Finally, we identified HLA-A*0201-restricted and highly conserved CD8 T-cell epitopes in the TSA56 antigen, which may be valuable tools for assessing cellular immunity against O. tsutsugamushi and developing an effective scrub typhus vaccine.Emerging Microbes & Infections (2017) 6, e116 doi:10.1038/emi.2017.106; published online 20 December 2017

The folding of monomeric antigens and their subsequent assembly into higher ordered structures are crucial for robust and effective production of nanoparticle (NP) vaccines in a timely and reproducible manner. Despite significant advances in in silico design and structure-based assembly, most engineered NPs are refractory to soluble expression and fail to assemble as designed, presenting major challenges in the manufacturing process. The failure is due to a lack of understanding of the kinetic pathways and enabling technical platforms to ensure successful folding of the monomer antigens into regular assemblages. Capitalizing on a novel function of RNA as a molecular chaperone (chaperna: chaperone + RNA), we provide a robust protein-folding vehicle that may be implemented to NP assembly in bacterial hosts. The receptor-binding domain (RBD) of Middle East respiratory syndrome-coronavirus (MERS-CoV) was fused with the RNA-interaction domain (RID) and bacterioferritin, and expressed in Escherichia coli in a soluble form. Site-specific proteolytic removal of the RID prompted the assemblage of monomers into NPs, which was confirmed by electron microscopy and dynamic light scattering. The mutations that affected the RNA binding to RBD significantly increased the soluble aggregation into amorphous structures, reducing the overall yield of NPs of a defined size. This underscored the RNA-antigen interactions during NP assembly. The sera after mouse immunization effectively interfered with the binding of MERS-CoV RBD to the cellular receptor hDPP4. The results suggest that RNA-binding controls the overall kinetic network of the antigen folding pathway in favor of enhanced assemblage of NPs into highly regular and immunologically relevant conformations. The concentration of the ion Fe2+, salt, and fusion linker also contributed to the assembly in vitro, and the stability of the NPs. The kinetic “pace-keeping” role of chaperna in the super molecular assembly of antigen monomers holds promise for the development and delivery of NPs and virus-like particles as recombinant vaccines and for serological detection of viral infections.

BACKGROUND:Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease that was recently identified in China, South Korea and Japan. The objective of the study was to evaluate the epidemiologic and clinical characteristics of SFTS in South Korea. METHODS/PRINCIPAL FINDINGS:SFTS is a reportable disease in South Korea. We included all SFTS cases reported to the Korea Centers for Disease Control and Prevention (KCDC) from January 2013 to December 2015. Clinical information was gathered by reviewing medical records, and epidemiologic characteristics were analyzed using both KCDC surveillance data and patient medical records. Risk factors for mortality in patients with SFTS were assessed. A total of 172 SFTS cases were reported during the study period. SFTS occurred throughout the country, except in urban areas. Hilly areas in the eastern and southeastern regions and Jeju island (incidence, 1.26 cases /105 person-years) were the main endemic areas. The yearly incidence increased from 36 cases in 2013 to 81 cases in 2015. Most cases occurred from May to October. The overall case fatality ratio was 32.6%. The clinical progression was similar to the 3 phases reported in China: fever, multi-organ dysfunction, and convalescence. Confusion, elevated C-reactive protein, and prolonged activated partial thromboplastin times were associated with mortality in patients with SFTS. Two outbreaks of nosocomial SFTS transmission were observed. CONCLUSIONS:SFTS is an endemic disease in South Korea, with a nationwide distribution and a high case-fatality ratio. Confusion, elevated levels of C-reactive protein, and prolonged activated partial thromboplastin times were associated with mortality in patients with SFTS.

ABSTRACT The newly emerging Middle East respiratory syndrome coronavirus (MERS-CoV) causes a severe respiratory infection with a high mortality rate (~35%). MERS-CoV has been a global threat due to continuous outbreaks in the Arabian peninsula and international spread by infected travelers since 2012. From May to July 2015, a large outbreak initiated by an infected traveler from the Arabian peninsula swept South Korea and resulted in 186 confirmed cases with 38 deaths (case fatality rate, 20.4%). Here, we show the rapid emergence and spread of a mutant MERS-CoV with reduced affinity to the human CD26 receptor during the South Korean outbreak. We isolated 13 new viral genomes from 14 infected patients treated at a hospital and found that 12 of these genomes possess a point mutation in the receptor-binding domain (RBD) of viral spike (S) protein. Specifically, 11 of these genomes have an I529T mutation in RBD, and 1 has a D510G mutation. Strikingly, both mutations result in reduced affinity of RBD to human CD26 compared to wild-type RBD, as measured by surface plasmon resonance analysis and cellular binding assay. Additionally, pseudotyped virus bearing an I529T mutation in S protein showed reduced entry into host cells compared to virus with wild-type S protein. These unexpected findings suggest that MERS-CoV adaptation during human-to-human spread may be driven by host immunological pressure such as neutralizing antibodies, resulting in reduced affinity to host receptor, and thereby impairs viral fitness and virulence, rather than positive selection for a better affinity to CD26. IMPORTANCE Recently, a large outbreak initiated by an MERS-CoV-infected traveler from the Middle East swept South Korea and resulted in 186 confirmed cases with 38 deaths. This is the largest outbreak outside the Middle East, and it raised strong concerns about the possible emergence of MERS-CoV mutations. Here, we isolated 13 new viral genomes and found that 12 of them possess a point mutation in the receptor-binding domain of viral spike protein, resulting in reduced affinity to the human cognate receptor, CD26, compared to the wild-type virus. These unexpected findings suggest that MERS-CoV adaptation in humans may be driven by host immunological pressure.

Kr-pok (kidney cancer-related POZ domain and Krüppel-like protein) is a new proto-oncogenic POZ-domain transcription factor. Fatty acid synthase gene (FASN) encodes one of the key enzymes in fatty acids synthesis and is the only enzyme that synthesizes fatty acids in cancer cells. Sp1 and SREBP-1c are the two major transcription activators of FASN. We investigated whether Kr-pok modulates transcription of the FASN. FASN expression is significantly decreased in Kr-pok knockout murine embryonic fibroblasts. Coimmunoprecipitation, GST fusion protein pull-down, and immunocytochemistry assays show that the zinc-finger domain of Kr-pok interacts directly with the bZIP DNA binding domain of SREBP-1. Electrophoretic mobility shift assay, oligonucleotide pull-down, and chromatin immunoprecipitation assays showed that Kr-pok changes the transcription factor binding dynamics of Sp1 and SREBP-1c to the SRE/E-box elements of the proximal promoter. We found that Kr-pok expression increased during 3T3-L1 preadipocyte differentiation and that FASN expression is decreased by the knockdown of Kr-pok. Kr-pok facilitates the SREBP-1c-mediated preadipocyte differentiation and/or fatty acid synthesis. Kr-pok may act as an important regulator of fatty acid synthesis and may induce rapid cancer cell proliferation by increasing palmitate synthesis.

Orientia tsutsugamushi, the causative agent of scrub typhus, is an obligate intracellular bacterium. Previously, a large number of genes that encode proteins containing eukaryotic protein-protein interaction motifs such as ankyrin-repeat (Ank) domains were identified in the O. tsutsugamushi genome. However, little is known about the Ank protein function in O. tsutsugamushi.To characterize the function of Ank proteins, we investigated a group of Ank proteins containing an F-box-like domain in the C-terminus in addition to the Ank domains. All nine selected ank genes were expressed at the transcriptional level in host cells infected with O. tsutsugamushi, and specific antibody responses against three Ank proteins were detected in the serum from human patients, indicating an active expression of the bacterial Ank proteins post infection. When ectopically expressed in HeLa cells, the Ank proteins of O. tsutsugamushi were consistently found in the nucleus and/or cytoplasm. In GST pull-down assays, multiple Ank proteins specifically interacted with Cullin1 and Skp1, core components of the SCF1 ubiquitin ligase complex, as well as the eukaryotic elongation factor 1 α (EF1α). Moreover, one Ank protein co-localized with the identified host targets and induced downregulation of EF1α potentially via enhanced ubiquitination. The downregulation of EF1α was observed consistently in diverse host cell types infected with O. tsutsugamushi.These results suggest that conserved targeting and subsequent degradation of EF1α by multiple O. tsutsugamushi Ank proteins could be a novel bacterial strategy for replication and/or pathogenesis during mammalian host infection.

BACKGROUND: Scrub typhus, caused by Orientia tsutsugamushi infection, is one of the main causes of febrile illness in the Asia-Pacific region. Although cell-mediated immunity plays an important role in protection, little is known about the phenotypic changes and dynamics of leukocytes in scrub typhus patients. METHODOLOGY/PRINCIPAL FINDINGS: To reveal the underlying mechanisms of immunological pathogenesis, we extensively analyzed peripheral blood leukocytes, especially T cells, during acute and convalescent phases of infection in human patients and compared with healthy volunteers. We observed neutrophilia and CD4(+) T lymphopenia in the acute phase of infection, followed by proliferation of CD8(+) T cells during the convalescent phase. Massive T cell apoptosis was detected in the acute phase and preferential increase of CD8(+) T cells with activated phenotypes was observed in both acute and convalescent phases, which might be associated or correlated with elevated serum IL-7 and IL-15. Interestingly, peripheral Treg cells were significantly down-regulated throughout the disease course. CONCLUSIONS/SIGNIFICANCE: The remarkable decrease of CD4(+) T cells, including Treg cells, during the acute phase of infection may contribute to the loss of immunological memory that are often observed in vaccine studies and recurrent human infection.

Lyme disease is a tick-borne infection in Korea. Here, clinical samples were collected from a 72-year old patient, with sudden onset of fever on April, 2018. The patient was passed away after 3rd day of doxycycline administration. The molecular diagnostic tests, nested polymerase chain reaction targeting 5S-23S rRNA intergenic spacer region (IGS) and multilocus sequence typing (MLST), showed positive for Borrelia afzelii from blood. Further, mutations in both 5S - 23S IGS and pepX allele of MLST were determined. Herein, we report the expected first death case by B. afzelii infection in Korea. [ABSTRACT FROM AUTHOR]