| Objective: In this study,we analyzed the distribution characteristics of neutralizing antibodies in different populations of HIV-1-infected patients in China and the potential factors affecting the neutralizing activity of antibodies,with the aim of providing guidelines for broad neutralizing antibody screening and information support for analyzing the correlation between virus characteristics,host immune response and disease process.Methods: A total of500 plasma samples of newly diagnosed HIV-infected patients in Hebei Province,China,from 2020 to 2021 were collected to screen the distribution of neutralizing antibodies in infected patients by plasma neutralization assay,and to analyze the correlation between the age,sex and mode of transmission of infected patients and the distribution of neutralizing antibodies through the statistics of background information of infected patients;the env gene sequence of the virulent strain in infected patients was obtained by PCR amplification and sequencing,and the gp120 gene sequence was analyzed.The correlation between the length of amino acid sequences of V1V2 region,V3 region and gp41 gene of gp120,the ratio of non-synonymous mutations to synonymous mutations(d N/d S),selection pressure,quasi-interspecies gene distance and plasma neutralizing antibody titer and neutralizing breadth of infected patients was analyzed by PCR amplification and sequencing;the enzyme immunoassay with restriction antigen affinity was used to distinguish new and previous infections and analyze their neutralizing antibody distribution.We used protein immunoblotting to detect the distribution of protein-specific antibodies and high-throughput sequencing to obtain the quasi-species sequence of the membrane region of the strain in the infected patients,and analyzed the correlation between dual infection and neutralizing antibody response by sequence analysis and SGA experiments to identify dual-infected samples.The main results are as follows:(1)A total of 285 plasma samples from 500 HIV-1-infected patients had neutralizing antibodies,accounting for 57% of the total,of which 197 samples,accounting for 39.4% of the total,had antibodies with cross-neutralizing activity.Among them,20 plasma samples had cross-neutralizing activity against different subtypes of virulent strains,providing an alternative for the screening of broad-spectrum neutralizing antibodies.(2)Major host factors affecting neutralizing antibody production: age,sex and mode of transmission of the host had an effect on neutralizing antibodies,among which the proportion of neutralizing antibodies with cross-neutralizing activity was highest in adult HIV-1-infected patients aged 20-40 years;compared with heterosexual HIV-1-infected patients,the neutralizing antibody titers were higher in the population of men who have sex with men;among heterosexual infected patients,men Among heterosexuals,the neutralizing antibody titers were also significantly higher in men than in women.(3)Regarding viral factors,the neutralizing antibodies in the plasma of CRF01＿AE and BC recombinant strains showed stronger neutralizing activity against the same subtype of pseudovirus(P<0.05 for both);the neutralizing breadth of neutralizing antibodies was positively correlated with the amino acid length of the V1V2 region,the selection pressure of the host and the quasispecies gene distance of the viral gp120 hypervariable region.(4)Twenty-two cases of dual infection were identified,and a higher proportion of these infected individuals had cross-neutralizing active antibodies in their plasma and higher antibody neutralization titers.(5)Neutralizing antibodies were more active and prone to crossneutralizing activity in previously infected patients than in newly infected patients,which may be related to the greater quasi-species diversity of viruses in previously infected patients.(6)In terms of antibody typing,Ig G1 content was significantly higher in infected patients with neutralizing antibodies in plasma than in those without neutralizing antibodies,and Ig G3-specific proteins were significantly more diverse than those without neutralizing antibodies,and p24-specific Ig G4 was widely distributed;among newly infected patients,p17-specific Ig G3 was significantly higher than Ig G1.In summary,this study elucidated the distribution of neutralizing antibodies in different populations of HIV-1-infected patients in China,revealed the effects of host age,sex and mode of transmission and genetic characteristics of the virus in neutralizing antibody titers and neutralizing widths,elucidated the effects of new infections on neutralizing antibody responses and virus protein-specific antibody typing.The results of the study provide options for further screening of broad neutralizing antibodies and explore the factors affecting the production of neutralizing antibodies such as viral characteristics,host immune response and disease process,which will promote the development of HIV vaccines and clinical therap-ies and provide data support for HIV prevention and treatment in China. |
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