Research On The Neutralization Immunogenicity Of Chinese HIV-1 Envelop Proteins

The human immunodeficiency virus (HIV) is the pathogen that cause acquired immunodeficiency syndrome (AIDS). The Ministry of Health of P.R.C released the latest news on the HIV/AIDS situation as of 2010. At the end of October, the cumulative number of reported HIV/AIDS infections was 370,393, of which 132,440 cases are of people living with HIV/AIDS and 68,315 are deaths from the disease. In 2009, there were approximately 480,000 new cases of HIV infections. The rate of increase has slowed, but the AIDS epidemic continued to rise, especially in some regions. Vaccines are responsible for the control of many infectious diseases and still hold promise for the eradication of HIV-1. HIV-1 broadly neutralizing antibodies (bNAbs) not only delay the progress of the disease can also prevent HIV-1 infection. Unfortunately, despite many efforts, it has not yet been possible to efficiently trigger bNAbs at high titer. As reported, some HIV-1 patients (about 10% ~30%) could develop the cross-reactive serum which could neutralize diverse clinical virus isolates from widely different genetic backgrounds. HIV -1 subtypes are not distributed uniformly across the globe. The predominant subtypes of HIV-1 in China are B ’(or Thai B), BC or AE. HIV-1 subtypes differ in biological characteristics that are associated with disease, highlighting the study of immune serum induced by Chinese HIV-1 pandemic strains.HIV-1 psedoviruses are widely applied in the analysis of neutralization assay. In the project, 46 strains of pseudoviruses, including those from the international recommended references and from the China popular viruses, were produced by transecting backbone plasmid pSG3△Env and envelop plasmid into 293T cells. These viruses were from subtype AE, B, B ’, BC, and C. As widely accepted and also proved in the project, monoclonal antibodies b12, 2G12, 2F5 and 4E10 could neutralize some of the pseudoviruses, which implied that the viruses stock could be employed in the neutralization analysis on the sera samples. In the Youan cohort, the sera and virus from 39 HIV-1 patients were screened and analyzed in depth. Among of them, 17 sera samples could not neutralize any viruses except those sensitive strains, 8 sera samples could only neutralize viruses from one clade and 14 sera samples could neutralize viruses from more than 2 clade. At the same time, these cross-neutralizing samples still showed preferred neutralization against viruses from the antilogous subtypes. And there was a trend that broader neutralizing antibody responses were observed with longer infection periods.The neutralization specificity was resolved with V3 peptide adsorption assay and virus capture competitive inhibition test. The neutralization potency against SF162 could be reduced in some sera, especially those with limited neutralization breadth. Yet, V3 antibodies may be not involved in the neutralization potency in the sera with broad breadth. CD4bs antibodies may mediate broadly neutralizing activity in these sera. And in some sera, NJ019 i.e., have developed the newly identified VRC01-like and VRC03-like antibodies, which may contribute to the broad neutralization. 2G12-like antibodies could also be detected in the broadly neutralizing sera of NJ019. Besides the Chinese HIV-1 patients’sera, the rabbits’sera, primed by the DNA vaccine and boosted by protein vaccine encoding and expressing the consensus gp120 sequences from Chinese BC HIV-1 viruses, were also prepared and profiled to get clues about the artificial induction of bNAbs. Compared with the gp120 protein alone, the combined immunization with DAN vaccine priming and protein vaccine boosting could induce higher gp120 specific antibodies. More importantly, the sera from DNA + protein immunization could not only neutralize the sensitive strain SF162 but also could neutralize the primary isolates from the antilogous subtype BC. The neutralization potency against SF162, but not the BC pseudoviruses, could be drastically eliminated by V3 peptide adsorption. And the sera from DNA + protein immunization but not protein alone immunization could inhibit the virus capture by b12, suggesting that CD4bs antibodies may be involved in the neutralization against BC primary isolates. VRC01-like, VRC03-like or 2G12-like antibodies could not be detected in the sera immunized by protein alone or DNA + protein.In summary, the study on the sera neutralization, which implied the immunogenicity of HIV-1 envelop proteins, would be helpful to understand the immune response in the HIV-1 infection and design the vaccines aiming to induce the bNAbs. The consensus subtype BC gp120 immunogens could induce the neutralizing antibody response, and are amenable to be included in the potential components of future Chinese AIDS vaccines...