Sequence And Neutralization Properties Of Functional Env Genes From HIV-1 Infected Individuals With Broadly Neutralizing Activities

BackgroundNeutralizing antibody is capable of blocking viral infection of host target cells and is the main immune protection component of an effective viral vaccine. But current approaches of envelope protein-based HIV vaccine failed to induce an efficient broadly neutralizing antibody response, which may be partly due to the intrinsic properties of envelope protein genes. To explore the sequence and functional characteristics of env genes from HIV-1 infected individuals with broadly neutralizing activities, as well as phenotypic properties of functional env-based pseudoviruses, will help us to understand the mechanism of the body’s immune system how to recognize antigens and how to generate broadly neutralizing HIV-1 antibodies. This kind of information is useful for the design of immunogens designed to induce broadly neutralizing antibody immune responses.ObjectiveTo explore the sequence properties of functional env genes from HIV-1 infected individuals with broadly neutralizing activities, and to analyze the neutralization phenotype of functional env gene-based pseudovirus against broadly neutralizing monoclonal antibodies, autologous and heterologous plasma samples.MethodsTo amplify the full length functional env genes from samples with broadly HIV-1 neutralizing activities; To co-transfect 293T/17 cells with the representative plasmids and HIV-1 backbone plasmids to prepare pseudoviruses; To analyze the neutralization sensitivities of functional env gene-based pseudovirus against broadly neutralizing monoclonal antibodies, autologous and heterologous plasma samples, respectively; To sequence the functional env genes and analyze the genetic properties and key amino acids mutation associated with broadly HIV-1 neutralizing activities using the Bioedit, Mega, Geno2pheno soft wares.Results1、28 representative functional env genes were identified from plasma samples of CBJC437, CBJC501 and CBJC515 with broadly HIV-1 neutralizing activities, among them,15 sequences from CBJC437,9 from CBJC501 and 4 from CBJC515.2、Sequence analysis shows that V1V2、V4 regions with bigger genetic distance and V3、V5 regions with minor genetic distance. All functional env genes were CCR5-tropic, SGA sequences mostly were CCR5-tropic based, but over time, some viruses switched to CXCR4 tropism.3、Certain key amino acid mutations were identified among the cloned functional env genes; these key sites were associated with broadly HIV-1 neutralizing activities.4、All functional env gene-based pseudoviruses were sensitive to 2F5 and 10E8 neutralization, while varying sensitivities exist for 2G12,4E10,12A21, PGT121, PGT135 and VRC01 neutralization.5、Most viruses at each time point could be autologously neutralized by contemporaneous plasma samples and viruses at early time points were more sensitive to later plasma samples; and most viruses were also sensitive to neutralization by subtype-matched heterologous plasma samples.ConclusionThe functional env gene-based pseudoviruses from samples with broadly HIV-1 neutralizing activities were sensitive to 2F5 and 10E8 neutralization. And varying sensitivities were observed in sensitivity to 2G12,4E10,12A21, PGT121, PGT135 and VRC01 neutralization. Most viruses at each time point could be self-neutralized by contemporaneous plasma samples and viruses at early time points were more sensitive to later plasma samples; and most viruses were also sensitive to neutralization by subtype-matched heterologous plasma samples.