Assessing the duration of neutralizing antibodies (nAbs) following SARS-CoV-2 infection or vaccination is critical to evaluate the protective immunity and formulate public health strategies. In this study, SARS-CoV-2 Ab ELISA (enzyme-linked immunosorbent assay), chemiluminescent microparticle immunoassay (CMIA), as well as pseudovirus neutralization test (PVNT) were performed in two cohorts, convalescent patients (CP) from coronavirus disease 2019 (COVID-19) and BBIBP-CorV vaccinated population. It was found that nAbs and binding antibodies emerged at 14 days post the 1st dose of vaccination, reached peaks at 28 days after 2nd dose vaccination and then gradually declined over time. CP-6M (convalescent patients up to 6 months) from COVID-19 presented stronger nAbs or binding antibodies responses than vaccinees 90 days or 180 days after 2nd dose vaccination. CMIA or SARS-CoV-2 Ab ELISA correlated well with PVNT with high consistency in the two cohorts. It shown that nAbs and binding antibodies can keep 6 months both in CP and vaccinees. Most importantly, our data show the application of using CMIA and SARS-CoV-2 Ab ELISA as rapid screening tests for nAb titer and could be used as alternative strategies for quickly evaluating SARS-CoV-2 nAbs responses in vaccine research.
This study aimed to reconstruct the origin and worldwide epidemic history of human immunodeficiency virus (HIV) 1 subtype C and comprehend how HIV-1 subtype C was introduced into and spread throughout China in the form of B/C recombinant strains. Envelope sequences of HIV-1 subtype C and some other subtypes deposited before December 31, 2020 were downloaded from the Los Alamos HIV Database and the Chinese National Center for AIDS/STD Control and Prevention Database. The available sequences were screened for quality, and Bayesian analysis was used to build the maximum clade credibility evolutionary tree to analyze and judge the origin and spread of HIV-1 subtype C. HIV-1 subtype C originated in central Africa around 1952, then spread to southern Africa around 1969 and to eastern Africa around 1973. HIV-1 subtype C from southern Africa was introduced into India in 1977. HIV-1 subtype C of eastern Africa was introduced into Brazil in 1987. Indian HIV-1 subtype C was exported to China in three migration events during the period from 1986 to 1989. The two predominant recombinants in China (CRF07_BC and CRF08_BC) emerged in 1988 and 1990, respectively. Other B/C recombinants, namely, CRF64_BC, CRF61_BC and CRF62_BC, originated in 1993, 2002 and 2000, respectively. Our study has reconstructed the global origin and evolutionary history of HIV-1 subtype C. In addition, our study demonstrated that the Chinese HIV-1 subtype C originated from three related Indian lineages around the mid to late 1980s and, since then, has formed some B/C recombinants with subtype B that caused a widespread epidemic in China.
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