3 JPT microarray analysis of IgG specificity in DP6-001 vaccinee sera (Group A and Group B, at 1:1000 dilution) against different regions of individual gp120 proteins

3 JPT microarray analysis of IgG specificity in DP6-001 vaccinee sera (Group A and Group B, at 1:1000 dilution) against different regions of individual gp120 proteins.The heatmap indicates mean binding intensity from Group A (Panel a) or Group B (Panel b) against each gp120 region. parameters in human volunteers receiving the PDPHV regimen. Antibody responses were assessed using IgG isotype and gp70-V1V2-binding ELISAs, peptide arrays, and antibody-dependent cellular cytotoxicity (ADCC) assays. B cell ELISPOT was used to detect gp120-specific memory B cells. Our results showed that the gp120-specific antibodies were primarily of the IgG1 isotype. HIV-1 envelope protein variable regions V1 and V2 were actively targeted by the antibodies as determined by Vegfa specific binding to both peptide and V1V2-carrying scaffolds. The antibodies showed potent and broad ADCC responses. Finally, the B cell ELISPOT analysis demonstrated persistence of gp120-specific memory B cells for at least 6?months after the Valproic acid last dose. These data indicate that broadly reactive binding Abs and ADCC responses as well as durable gp120-specific memory B cells were elicited by the polyvalent heterologous prime-boost vaccination regimens and showed great promise as a candidate HIV vaccine. Subject terms: Vaccines, Public health Introduction Development of a safe and effective vaccine is crucial for the control of the HIV pandemic. After the moderate success of the heterologous viral vector prime-protein boost approach in the RV144 trial in Thailand1, the HIV vaccine field continues to explore the various combinations of prime and boost modalities to improve the immunogenicity of preventive HIV vaccine candidates2C5. Antibodies are known to be the key elements in vaccine-induced protection against a wide range of human infectious diseases, but the protective mechanisms are diverse. In recent years, it became clear that candidate HIV vaccines may elicit immune protection via Fc-mediated antibody functions6C10. In particular, detailed biomarker analysis of the RV144 trial showed that the gp70-V1V2-specific antibody responses and Fc-mediated antibody functions inversely correlated with the risk of infection while there were no broadly neutralizing antibodies (bNAbs) detected in protected volunteers6,11. This is an important finding because many previous HIV vaccine studies have only focused on bNAbs12C14. The importance of Fc-mediated antibody functions was also reported from the study results in NHP models and HIV infected patients. ADCC responses were reported to inversely correlate with virus set point in acute SIV infection15 and in vaccinated animals following SHIV challenge16,17. In HIV-1 infection, a direct role for ADCC responses was shown in controlling virus replication by delaying overt disease18C20. HIV mother-to-child transmission (MTCT) studies also demonstrated that passively acquired Ab mediating ADCC responses could reduce mortality in HIV infected infants21, and higher pre-existing ADCC responses against exposure strains associated with less likelihood of HIV-1 MTCT Valproic acid and lower morbidity in infected infants22. Therefore, one of the major tasks in the HIV vaccine field is to further improve on the ADCC responses achieved by RV1445. RV144 used the ALVAC prime-protein boost vaccine approach which belongs to the heterologous prime-boost strategy23. Another heterologous prime-boost approach is the DNA prime-protein boost which has been studied by our team in the last Valproic acid two decades24C28 including our first HIV vaccine clinical trial DP6-00129. Using DNA-encoded gp120 immunogens to prime the host immune system with the matched gp120 proteins boost is a promising approach leading to high titers of functional antibodies and cell-mediated immune responses29,30,31. More importantly, the polyvalent antigen formulation has been shown effective in eliciting antibody responses across different clades of HIV-1 in the DP6-001 trial. The gp120-specific serum IgG responses were robust and broadly cross-reactive against gp120 antigens from a wide range of major HIV-1 clades and the neutralizing activities from volunteers immune sera were also cross-reactive against pseudotyped viruses expressing Env antigens from clades of A, B, C, and AE29,31. Furthermore, the mAbs isolated from DP6-001 volunteers showed broad binding to both autologous and heterologous Env antigens and mediated potent ADCC response32. Since the publication of initial reports on the overall immunogenicity of DP6-001 vaccine, much new information has been learned in the HIV-1 vaccine field such as the roles of IgG isotypes and the identification of V1V2 region as the possible target for ADCC responses11,33. In the current report, data from new studies are presented to provide more detailed assessment of the additional humoral responses including IgG isotypes, recognition profiles of HIV-1.