BACKGROUND: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a novel viral pneumonia (COVID-19), which is rapidly spreading throughout the world. The positive result of nucleic acid test is a golden criterion to confirm SARS-CoV-2 infection, but the detection features remain unclear. METHODS: We performed a retrospective analysis in 5630 high-risk individuals receiving SARS-CoV-2 nucleic acid tests in Wuhan, China, and investigated their characteristics and diagnosis rates. RESULTS: The overall diagnosis rate was 34.7% (1952/5630). Male ( P = 0.025) and older populations ( P = 2.525 × 10 ^–39 ) were at significantly higher risk of SARS-CoV-2 infection. People were generally susceptible, and most cases concentrated in people of 30–79 years. Furthermore, we investigated the association between diagnosis rate and the amount of testing in 501 subjects. Results revealed a 1.27-fold improvement (from 27.9% to 35.5%) of diagnosis rate from testing once to twice ( P = 5.847 × 10 ^–9 ) and a 1.43-fold improvement (from 27.9% to 39.9%) from testing once to 3 times ( P = 7.797 × 10 ^–14 ). More than 3 testing administrations was not helpful for further improvement. However, this improvement was not observed in subjects with pneumonia ( P = 0.097). CONCLUSION: All populations are susceptible to SARS-CoV-2 infection, and male and older-aged populations are at significantly higher risk. Increasing the amount of testing could significantly improve diagnosis rates, except for subjects with pneumonia. It is recommended to test twice in those high-risk individuals whose results are negative the first time, and performing 3 tests is better, if possible. FUNDING: This work was supported by National Mega Project on Major Infectious Disease Prevention (no. 2017ZX10103005-007) and National Key Research and Development Program of China (no. 2018YFE0204500).

Human hepatitis B virus core protein (HBc) is a structural protein of the hepatitis B virus (HBV) and contributes to HBV regulation of host-cell transcription. However, the mechanisms of transcriptional regulation remain poorly characterized. To dissect the function of HBc, a yeast two-hybrid was performed to identify HBc-binding proteins, and the C-terminal of BRG1/hBRM-associated factors 200 (BAF200C) was identified. Then, the existence of HBc interactions with BAF200C and full-length BAF200 was confirmed via co-immunoprecipitation assays in 293T, HepG2 and HepG2-NTCP cells. Furthermore, we show that the binding between HBc and BAF200 was of vital importance to HBc mediated downregulation of interferon-induced transmembrane protein 1 (IFITM1) expression, and the mechanisms for the downregulation were disclosed as follows. Basal level of IFITM1 expression depends on BAF200, rather than the JAK–STAT1 pathway. The interaction of HBc with BAF200 disturbs the stability of the polybromo-associated BAF (PBAF) complex and results in the suppression of IFTM1 transcription. Finally, the antiviral effects of IFITM1 on cell proliferation and HBV replication were found to be partially restored when HBc was co-transfected with BAF200. Collectively, our findings indicate that HBc plays a role in HBV resistance against the antiviral activities of IFNα, providing details about HBV evasion of host innate immunity.

Carbapenem-resistant Salmonella has recently aroused increasing attention. In this study, a total of four sequence type 36 Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium) isolates were consecutively isolated from an 11-month-old female patient with a gastrointestinal infection, of which one was sensitive to carbapenems and three were resistant to carbapenems. Via antibiotic susceptibility testing, a carbapenemases screening test, plasmid conjugation experiments, Illumina short-reads, and PacBio HiFi sequencing, we found that all four S. Typhimurium isolates contained a bla_CTX-M-14-positive IncI1 plasmid. One carbapenem-sensitive S. Typhimurium isolate then obtained an IncHI2 plasmid carrying bla_NDM-1 and an IncP plasmid without any resistance genes during the disease progression. The bla_NDM-1 gene was located on a new 30 kb multiple drug resistance region, which is flanked by IS26 and TnAs2, respectively. In addition, the ST_F0903R isolate contained eight tandem copies of the ISCR1 unit (ISCR1-dsbD-trpF-ble-bla_NDM-1-ISAba125Δ1), but an increase in MICs to carbapenems was not observed. Our work further provided evidence of the rapid spread and amplification of bla_NDM-1 through plasmid. Prompting the recognition of carbapenem-resistant Enterobacterales and the initiation of appropriate infection control measures are essential to avoid the spread of these organisms.