With the combination mutants LN40KD (R373K plus N386D) and LN40KV (R373K plus T388V), neutralizing sensitivity to the sera of LN40 gp120 DNA vaccine-primed animals was almost completely lost (< 0

With the combination mutants LN40KD (R373K plus N386D) and LN40KV (R373K plus T388V), neutralizing sensitivity to the sera of LN40 gp120 DNA vaccine-primed animals was almost completely lost (< 0.001) (Table 3). were capable of eliciting NAbs against only homologous and sensitive viral isolates. Further analysis exposed the specificity of NAbs elicited from the LN40 antigen mapped to limited residues within or flanking the CD4 binding site. Certain important structural determinants Hyal2 were recognized that could differentiate main Env immunogens based on their potential to elicit broader NAbs. This progress will facilitate PRT 4165 the rational design of effective HIV-1 vaccine formulations with ideal Env antigens. INTRODUCTION Protecting antibodies are expected to play important roles in the development of an effective prophylactic AIDS vaccine, but overcoming the high degree of antigen diversity is definitely a major challenge in eliciting broadly neutralizing antibody (NAb) reactions against HIV-1. A less-studied but theoretically attractive approach for AIDS vaccine development is the use of polyvalent Env formulations (17). Given the high degree of sequence variation among main HIV-1 isolates, the prevailing look at for many years has been that it is difficult to produce a polyvalent HIV vaccine that can elicit broad antibody reactions to encompass circulating viral isolates with varied genetic backgrounds. It has been theoretically hard to consider producing a polyvalent HIV vaccine formulation using randomly selected Env proteins, because a subunit-based vaccine, using recombinant HIV-1 Env proteins alone, was unable to elicit meaningful NAbs against main viral isolates (10, 22). In fact, two failed phase III efficacy tests using a recombinant subunit protein-based PRT 4165 HIV vaccine approach included only two Env antigens for each formulation, one of which was from a T cell line-adapted (TCLA) disease. However, our recent progress in both animal and human being immunogenicity studies offers demonstrated the DNA prime-protein boost immunization approach is more effective than DNA or protein only in eliciting improved antibody reactions with clearly positive NAb activities against main Env antigens, including resistant ones (26, 27, 30, 31, 33). More significantly, polyvalent formulations with multiple main Env antigens were more effective in eliciting broader NAbs than were monovalent main Env antigens (27, 33). Inside a phase I clinical study, PRT 4165 the polyvalent DNA prime-protein boost HIV vaccine, using five main Env antigens, was able to elicit broad NAbs against a wide range of main Env antigens of viruses isolated from subtypes A to E (32), indicating the encouraging potential of polyvalent Env HIV vaccines. In the above studies, main Env antigens included in the polyvalent formulations were randomly selected based on what was available at the start of the study, while the investigators tried to keep up a balanced representation of major HIV-1 subtypes. Since then, additional main Env antigens have become available with well-characterized phenotypic features associated with the unique viral isolates. It will be interesting to determine whether any particular phenotypes of the original viral isolates can preselect Env antigens with a greater ability to elicit NAb reactions, and also whether a polyvalent Env formulation, with such rationally selected Env antigens, will achieve actually broader and more potent NAbs than the early generation of PRT 4165 polyvalent formulations with randomly selected Env antigens. In the current report, studies were carried out to determine whether variations in immunogenic potential exist between two previously PRT 4165 reported main Env antigens with closely related gene sequences and completely different phenotypic features. Clade B main Env antigens LN40 and B33 (19) were isolated from a single HIV-1-infected individual. These antigens share over 90% amino acid identity; however, despite the high degree of sequence homology, they display different phenotypic properties. The B33 Env is definitely highly macrophage tropic, maintains a high affinity for CD4, and is sensitive to neutralization by monoclonal antibody (MAb) IgG1 b12 but resistant to MAb 2G12 (7, 19C21), while the LN40 Env has the reverse phenotype of B33, as it is definitely poorly macrophage tropic, has only a low affinity for CD4, and is resistant to the MAb IgG1 b12 but sensitive to MAb 2G12 (7, 19C21). With this.