Objective  To analyze the sequence characteristics of HIV-1 envelope genes (env) and their neutralization sensitivity from a HIV-1 broad neutralizer.

  Methods  The env genes were amplified from the blood samples at two different follow-up time points by the single genome amplification method. The sequence alignment and phylogenetic tree construction were performed after sequencing. The characteristics of env genes and the amino acid of CD4 binding site (CD4bs) were analyzed.The representative env genes were cloned into pcDNA^TM3.1 vector, and the pseudovirus were prepared by transfecting it with the skeleton plasmid pSG3△env into 293T cells. Screening out the functional membrane protein by testing its infectivity, and then neutralizing the functional membrane protein pseudovirus with four different broadly neutralizing antibodies to analyze the neutralization characteristics of the Env protein.

  Results  A total of 43 full-length env genes were obtained from the blood samples at two time points. Evolutionary analysis showed that the sequences at the two time points were clustered, the divergence of env gene sequences increased with time. The analysis of the variable region of the virus membrane protein gene showed that the number of glycosylation sites in V5 region decreased over time, and 16% of the sequences in the latter time point evolved two additional cysteine in V1 region. Neutralization test showed that whether extra cysteines were inserted into V1 region was not related to the sensitivity of pseudoviruses to V3-glycan-dependent class antibody, the deletion of N460 glycosylation site in V5 region leads to a slight decrease in the sensitivity of pseudoviruses to CD4bs-directed neutralizing antibody.

  Conclusions  Theviral envelope genes continue to evolve under the pressure of humoral immunity. Amino acid mutations in the key neutralizing epitopes lead to the viral neutralization escape.