Résumé
Objective:To analyze the genome characteristics and variations in nucleotides and amino acids of SARS-CoV-2 causing an outbreak in Henan Province in November 2021 and perform the traceability analysis.Methods:In this study, throat swab specimens from cases in the acute phase were collected and tested for the nucleic acids of SARS-CoV-2 by real-time fluorescent RT-PCR. SARS-CoV-2 nucleic acid-positive samples were subjected to high-throughput genome sequencing and whole-genome alignment analysis.Results:The median Ct values of ORF1ab gene and N gene in 70 positive specimens was 26.41 (15.58 to 39.27) and 24.43 (12.04 to 39.74), respectively. Compared with the sequence of Wuhan-Hu(NC_045512) reference strain, 47 to 49 nucleotide mutations sharing 47 nucleotide mutation and 41 amino acid mutations were found in 63 strains of successfully sequenced SARS-CoV-2. Nine nucleotide mutations and 12 amino acid mutations were found in the spike protein. The index case shared 47 mutations with the Russian imported cases in Henan Province on October 14 and the local cases in Jiangxi Province in October. Moreover, their genomes were highly homologous and they all belonged to the Delta variant (AY.122 evolutionary branch).Conclusions:Continuous monitoring of imported COVID-19 cases and prolonging the period of quarantine were needed to reduce the risk of local outbreak and epidemic caused by imported COVID-19 cases. Analysis of the genomic characteristics of SARS-CoV-2 and the variations in nucleotides and amino acids was conducive to trace the origin of COVID-19 outbreak quickly and provide reference for precise control.
Résumé
【Objective】 To analyze the characteristics of gene mutation in S region of blood donors with occult hepatitis B virus infection (OBI) in Huzhou area. 【Methods】 A total of 60 107 blood samples in Huzhou between October 2018 and June 2020 were collected by our blood station. Among them, 52 samples were NAT, yield and their epidemiological characteristics were analyzed. Twenty-seven OBI out of the 52 NAT yield samples were included in experimental group. Other eight HBV-infected individuals with positive HBsAg, core antibody (anti-HBc) and HBV-DNA were selected as positive control. Liver function and 5 serological markers of HBV were compared between the two groups, and HBV genotypes and amino acid mutation in S region in the two groups were analyzed. 【Results】 The number of NAT-yield samples were different by gender, age, and educational background (P0.05). Surface antigen (HBsAg) in the experimental group was significantly lower than that in the control group, while surface antibody (anti-HBs) and e antibody (anti-HBe) were significantly higher than those in the control group (P<0.05). Twenty sequences in S region were obtained from the experimental group, including 4 in S region and 16 in preSS region; 16 cases with type C and 4 cases with type B. 【Conclusion】 The follow-up of NAT-yield blood donors in Huzhou area should be conducted. Compared with HBV infected individuals with positive HBsAg, anti-HBc and HBV-DNA, those with OBI have a higher gene mutation rate in S region.
Résumé
The non-structural (NS1) protein is a multifunctional molecular protein encoded by influenza A virus genome. NS1 plays an important role in inhibition of host immune responses. In order to assess the cellular localization of NS1 in different influenza A virus subtypes, we performed the immunofluorescence assay to observe the cellular location of NS1 after infection with influenza A virus WSN (H1N1), PR8 (H1N1), CA04 (H1N1), SD (H9N2) and AH01 (H7N9) in A549 cells and MDCK cells respectively. According to the results, NS1-WSN and NS1-PR8 accumulated mainly in cytoplasm at 24 h post infection, while the NS1-CA04 and NS1-SD appeared major in the nucleus. We also observed localization of NS1 by transfected 293T cells with plasmids which encoding the full-length NS1 from WSN, SD and AH01. The key sites which might determine the different cellular localization of NS1 were chosen by sequence alignment, and seven residues which were different between WSN, PR8 and CA04, SD and AH01 were finally focused. However, we found that single mutation of these residues could not alter the localization of NS1. The data indicated that the difference of location might not be caused by substitution of a single site, which contributes to our understanding of the diverse regulation of host factors during different subtypes of influenza virus infection.