ABSTRACT
Objective@#The pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been engendering enormous hazards to the world. We obtained the complete genome sequences of SARS-CoV-2 from imported cases admitted to the Guangzhou Eighth People's Hospital, which was appointed by the Guangdong provincial government to treat coronavirus disease 2019 (COVID-19). The SARS-CoV-2 diversity was analyzed, and the mutation characteristics, time, and regional trend of variant emergence were evaluated.@*Methods@#In total, 177 throat swab samples were obtained from COVID-19 patients (from October 2020 to May 2021). High-throughput sequencing technology was used to detect the viral sequences of patients infected with SARS-CoV-2. Phylogenetic and molecular evolutionary analyses were used to evaluate the mutation characteristics and the time and regional trends of variants.@*Results@#We observed that the imported cases mainly occurred after January 2021, peaking in May 2021, with the highest proportion observed from cases originating from the United States. The main lineages were found in Europe, Africa, and North America, and B.1.1.7 and B.1.351 were the two major sublineages. Sublineage B.1.618 was the Asian lineage (Indian) found in this study, and B.1.1.228 was not included in the lineage list of the Pangolin web. A reasonably high homology was observed among all samples. The total frequency of mutations showed that the open reading frame 1a (ORF1a) protein had the highest mutation density at the nucleotide level, and the D614G mutation in the spike protein was the commonest at the amino acid level. Most importantly, we identified some amino acid mutations in positions S, ORF7b, and ORF9b, and they have neither been reported on the Global Initiative of Sharing All Influenza Data nor published in PubMed among all missense mutations.@*Conclusion@#These results suggested the diversity of lineages and sublineages and the high homology at the amino acid level among imported cases infected with SARS-CoV-2 in Guangdong Province, China.
Subject(s)
Humans , Amino Acids , COVID-19/epidemiology , Genomics , Mutation , Phylogeny , SARS-CoV-2/geneticsABSTRACT
<p><b>OBJECTIVE</b>To study PD-1 and PD-L1 expressions during 24 weeks telbivudine antiviral treatment in patients with chronic hepatitis B (CHB) and to explore the relationship between PD-1 expression and HBeAg/HBeAb seroconversion.</p><p><b>METHODS</b>Ten CHB cases with HLA-A2 and HBeAg positive were treated with telbivudine 600 mg/d orally for 24 weeks. Fresh blood samples were collected at week 0, 12 and 24 after treatment. HBV-specific CD8+ T cells were expanded in vitro. Cell culture medium were collected for interferon gamma (IFNgamma) detection. Flow cytometry was used to detect the HLA-A type, PD-1, PD-L1 and HBV specific CD8+ T cells. The expressions of PD-1 and PD-L1, the counts of HBV-specific CD8+ T cells in circulating CD8+ lymphocytes, and IFNgamma concentration in culture medium were evaluated during antiviral treatment.</p><p><b>RESULTS</b>At week 0, 12 and 24 after telbivudine treatment, 7 of 10 patients were HBV DNA undetectable, 2 were HBeAg seroconversion and 2 were HBeAg lose but anti-HBe negative. The frequency of PD-1-positive PBMCs were 52.1%+/-17.0%, 39.1%+/-18.2% and 23.4%+/-16.3% (week 24 vs week 0, P < 0.01) respectively; PD-L1 positive PBMCs were 45.6%+/-15.4%, 34.6%+/-16.2% and 20.9%+/-9.5% respectively(week 24 vs week 0, P < 0.01; week 24 vs week 12, P < 0.05). The frequency of PD-1-positive CD8+ T cells were 76.2%+/-10.4%, 66.5%+/-15.4% and 49.5%+/-25.3% respectively (week 24 vs week 0, P < 0.01; week 12 vs week 0, P < 0.05; week 24 vs week 12, P < 0.05); HBV-specific CD8 cells were 1.3%+/-0.5%, 1.5%+/-1.0% and 2.2%+/-1.5%; IFNgamma levels in cell culture medium were (91.7+/-82.1) pg/ml, (99.4+/-93.5) pg/ml and (109.5+/-86.6) pg/ml. A remarkable decrease of PD-1 and PD-L1 expressions and increase of HBV-specific CD8+ T cells were observed in patients who had HBeAg/HBeAb seroconversion at week 24.</p><p><b>CONCLUSIONS</b>Direct suppression of HBV replication by telbivudine in CHB patients can decrease PD-1 and PD-L1 expressions and restore HBV-specific CD8+T cells. The relationship between the changes of PD-1 expression and HBeAg/HBeAb seroconversion during antiviral therapy in HBeAg-positive patients need to confirm by future study.</p>