Enhancement of human immunodeficiency virus type 1 infectivity by replacing the region including Env derived from defective particles with an ability to form particle-mediated syncytia in CD4+T cells

An HIV/AIDS Prophylactic vaccine is possible

One needs to think outside of the box, as one of us (Ronald B Luftig) learned from many years as a mathematician, and a biophysicist.In this short Review, the need to focus on producing high levels of neutralizing antibodies (NAbs) to incoming and conformationally altered virus after it has bound to CD4+ cells is essential.Increasing the number of gp120 molecules on the surface of L-2 particles, could allow for an enhanced number of NAbs.The attempt at increasing CD8+ T cell responses in recent vaccine trials has not worked perhaps because it may have allowed HIV to enter into remote sanctuaries. Our approach focuses on increasing NAbs, before high levels of CD8+ T cells are produced.

Amino acid 36 in the human immunodeficiency virus type 1 gp41 ectodomain controls fusogenic activity: implications for the molecular mechanism of viral escape from a fusion inhibitor

We have previously described a human immunodeficiency virus type 1 (HIV-1) proviral clone, pL2, derived from defective viral particles with higher fusogenicity than the prototypic NL4-3 virus. In this study, we attempted to determine the region that confers the enhanced fusion activity by creating envelope recombinants between pL2 and pNL4-3, as well as point mutants based on pNL4-3. The results indicate that amino acid 36 of gp41 is key for the fusogenic activity and infectivity enhancement and that glycine 36 (36G) of gp41 in pL2 is conserved in nearly all HIV-1 isolates except for pNL4-3. The mutation 36G-->D in a primary-isolate-derived Env decreased syncytium-forming activity and infectivity. The assays for cell-cell fusion and viral binding suggested that the enhanced fusion mediated by the 36D-->G mutation is not due to increased binding efficiency but is directly due to actual enhancement of viral fusion activity. Interestingly, this amino acid position is exactly equivalent to that at which the mutation of HIV-1 isolates that have escaped from a fusion inhibitor, enfuvirtide (T-20), has been frequently observed. The correlation between these previous findings and our findings was suggested by structural analysis. Our finding, therefore, has implications for a molecular basis of the viral escape from this drug.

Different susceptibility of human immunodeficiency virus type 1 to Env gp41-derived synthetic peptides corresponding to the C-terminal heptad repeat region

Two functional domains, alpha-helical heptad repeat 1 (HR-1) and HR-2, located in the N-terminal and C-terminal regions of human immunodeficiency virus type 1 (HIV-1) Env gp41, respectively, play an important role in the fusion process. Synthetic 34-amino-acid peptide that contains the HR-2 region, named C34, has been shown to inhibit the HIV-1 fusion process. Here, we prepared six representative peptides (C34-B1, -B2, -A, -C1, -C2, and -E from subtypes B, A, C, and E, respectively) according to the sequences from the HIV sequence database of Los Alamos. All the C34 peptides had lower ability to inhibit the primary isolates (subtypes B and CRF01_AE) than subtype B laboratory strain LAI. On the other hand, the L-2 cell clone, isolated from persistently LAI-infected MT-4 cells (MT-4/LAI), showed unique C34 peptide sensitivities. L-2 virus has the same sequences at HR-1 and HR-2 regions as LAI, but showed higher syncytia formation activity than LAI. Interestingly, the sensitivity of L-2 was higher to C34-B2 and -A but slightly lower to C34-C1 at higher concentrations than MT-4/LAI, while C34-B1, -C2, and -E showed similar activity against both viruses. Thus, in addition to the sequences of the C34 peptide as well as of the HR-1 and HR-2 regions in target viruses used for fusion assays, the fusion inhibitory activities of C34 peptides seem to be affected by viral factor(s) other than the gp41 alpha-helical heptad repeats.