ABSTRACT
Background: The genome of SARS-CoV-2 has shown considerable variation during its spreading. Monitoring variations in the virus genome to understand the evolution and spread of the virus is extremely important. Methods: Seven SARS-CoV-2 strains (BB127, BB183, HB030, MAS525, HF3028, FY1494, and SZ005) circulating in Anhui Province, China were isolated and sequenced for evolutionary analysis. Five strains were further cultured in vitro and were subjected to viral growth assay, TCID50 assay, and detection of spike protein expression. Next generation sequence (NGS) analysis were applied to investigate the mutation frequencies throughout the whole genome at different time gradients in vitro. Findings: Our observations revealed that in vitro cultured SARS-CoV-2 virus had much higher mutation frequency (up to ~20 times) than that in infected patients, and the mutation in nonstructural protein 14 (nsp14) might increase the genomic mutation frequency. Different strains had various amount of spike protein which may positively correlated with the virus replication capacity but may be influenced by other viral factors. Interpretation: Our study suggested that SARS-CoV-2 has the potential to diversify under favorable conditions. Monitoring viral mutations is not only helpful for better understanding of virus evolution and virulence change, but also the key to prevent virus transmission and disease progression. SARS-CoV-2 genomic variation analysis may also provide potential ideas for more efficient vaccine development and clinical treatment. Funding: This work is funded by Special Project for Emergency Scientific and Technological Research on New Coronavirus Infection (YG, No. YD9110002001), Emergency Research Project of Novel Coronavirus Infection of Anhui Province (Grant numbers 202004a07020002; 202004a07020004), Postdoctoral Research Foundation of China (2020M670084ZX) and the Fundamental Research Funds for the Central Universities (WK9110000166; WK9110000167).Declaration of Interests: We declare no competing interests.Ethics Approval Statement: The study was conformed to the principles of the Declaration ofHelsinki and approved by the Ethics Committee of the First Affiliated Hospital of USTC..
Subject(s)
EmergenciesABSTRACT
Background: COVID-19 is a newly emerging disease caused by a novel coronavirus (SARS-CoV-2), which spread globally in early 2020. Asymptomatic carriers of the virus contribute to the propagation of this disease, and the existence of asymptomatic infection has caused widespread fear and concern in the control of this pandemic. Methods: : In this study, we investigated the origin and transmission route of SARS-CoV-2 in Anhui’s two clusters, analyzed the role and infectiousness of asymptomatic patients in disease transmission, and characterized the complete spike gene sequences in the Anhui strains. Results: : We conducted an epidemiological investigation of two clusters caused by asymptomatic infections sequenced the spike gene of viruses isolated from 12 patients. All cases of the two clusters we investigated had clear contact histories, both from Wuhan, Hubei province. The viruses isolated from two outbreaks in Anhui were found to show a genetically close link to the virus from Wuhan. In addition, new single nucleotide variations were discovered in the spike gene. Conclusions: : Both clusters may have resulted from close contact and droplet-spreading and asymptomatic infections were identified as the initial cause. We also analyzed the infectiousness of asymptomatic cases and the challenges to the current epidemic to provided information for the development of control strategies.
Subject(s)
COVID-19ABSTRACT
A significant, positive association between selenium status and prognosis of SARS-CoV-2 infection has been identified among COVID-19 patients in China. Moreover, a German study revealed a pronounced deficit of serum selenium and SELENOP concentrations in COVID-19 patients, and selenium deficiency was associated with mortality risk from COVID-19. The present study investigated the influence of SARS-CoV-2 on gene expression of host selenoproteins which mediate many beneficial actions of selenium. We found that SARS-CoV-2 suppressed mRNA expression of selenoproteins associated with ferroptosis (GPX4), endoplasmic reticulum stress (SELENOF, SELENOK, SELENOM and SELENOS) and DNA synthesis (TXNRD3), while SARS-CoV-2 increased gene expression of IL-6 (an inflammatory cytokine positively correlated with severity of COVID-19), in Vero cells. These results provide a deeper insight into the connection between selenium and SARS-CoV-2 pathogenesis.
Subject(s)
COVID-19ABSTRACT
We used the epidemic data of COVID-19 published on the official website of the municipal health commission in Anhui province. We mapped the spatiotemporal changes of confirmed cases, fitted the epidemic situation by the population growth curve at different stages and took statistical description and analysis of the epidemic situation in Anhui province. It was found that the cumulative incidence of COVID-19 was 156/100 000 by February 18, 2020 and the trend of COVID-19 epidemic declined after February 7, changing from J curve to S curve. The actual number of new cases began to decrease from February 2 to February 4 due to the time of case report and actual onset delayed by 3 to 5 days.
ABSTRACT
Background and Objective To analyze the impact of different patterns of migration flow in two cities, Hefei and Shenzhen, on the epidemic and disease control of Coronavirus Disease 2019 (COVID-19), in order to provide insight for making differentiated controlling policies. Methods We collected demographic and epidemiological information of confirmed COVID-19 cases in Hefei and Shenzhen between January 19 and February 11, 2020, from data officially published by the provincial and municipal Centers for Disease Control and Prevention (CDC). From these data we calculated basic reproduction number R0 to reflect the rate of spread of COVID-19 in these cities. Aggregated data of population migration during the same period was extracted from Baidu Migration. The change of R0 in the two cites were analyzed and compared. Spearman correlation analysis between R0 and population inflow from epidemic focus were performed. Results A total of 157 confirmed cases was identified in Hefei by 24:00 February 11, 2020, with an average age of 44.4{+/-}15.6 years, 74 female (47.1%) and 386 confirmed cases were identified in Shenzhen, with an average age of 45.15{+/-}17.99 years, 202 female (52.3%). Significant difference in the proportion of imported cases between the two cities was observed (Hefei vs Shenzhen, 24.2% vs 74.9%, p=0.000). Before January 31 2020, during the initial stage of the Level 1 Response to Major Public Health Emergencies, there was no significant association observed in Shenzhen between R0 and the proportion of population inflow from the epidemic focus (P =0.260, r=-0.452); meanwhile in Hefei, such association was strong (P =0.000, r=1.0). However, after the initial stage of response, the situation reversed. A weak association was observed in Shenzhen between be R0 and the proportion of population inflow from the epidemic focus (P=0.073, r=0.536) but not in Hefei (P =0.498, r=0.217). Conclusion Following Level 1 Response, consistent decline of R0 of COVID-19 was observed in both Hefei and Shenzhen. Different patterns of disease spread were observed in the two cities, driven by different patterns of population migration. This indicated that population migration should be taken into consideration when we set controlling policy of a novel infectious disease.