The HIV-1 vpr R77Q Mutant Induces Apoptosis, G2 Cell Cycle Arrest, and Lower Production of Pro-Inflammatory Cytokines in Human CD4+ T Cells.

Acquired immunodeficiency syndrome (AIDS) occurs when HIV depletes CD4+ helper T cells. Some patients develop AIDS slowly or not at all, and are termed long-term non-progressors (LTNP), and while mutations in the HIV-1 Viral Protein R (vpr) gene such as R77Q are associated with LTNP, mechanisms for this correlation are unclear. This study examines the induction of apoptosis, cell cycle arrest, and pro-inflammatory cytokine release in the HUT78 T cell line following infection with replication-competent wild-type strain NL4-3, the R77Q mutant, or a vpr Null mutant. Our results show a significant enhancement of apoptosis and G2 cell cycle arrest in HUT78 cells infected with R77Q, but not with WT NL4-3 or the vpr Null strain. Conversely, HUT78 cells infected with the WT virus show higher levels of necrosis. We also detected lower TNF and IL-6 release after infection with R77Q vs. WT. The apoptotic phenotype was also seen in the CEM cell line and in primary CD4+ T cells. Protein expression of the R77Q vpr variant was low compared to WT vpr, but expression levels alone cannot explain these phenotypes because the Null virus did not show apoptosis or G2 arrest. These results suggest that R77Q triggers a non-inflammatory apoptotic pathway that attenuates inflammation, possibly contributing to LTNP.

Use of 3M-052-AF with Alum adjuvant in HIV trimer vaccine induces human autologous neutralizing antibodies.

Stabilized trimers preserving the native-like HIV envelope structure may be key components of a preventive HIV vaccine regimen to induce broadly neutralizing antibodies (bnAbs). We evaluated trimeric BG505 SOSIP.664 gp140 formulated with a novel TLR7/8 signaling adjuvant, 3M-052-AF/Alum, for safety, adjuvant dose-finding, and immunogenicity in a first-in-healthy adult (n = 17), randomized, and placebo-controlled trial (HVTN 137A). The vaccine regimen appeared safe. Robust, trimer-specific antibody, and B cell and CD4+ T cell responses emerged after vaccination. Five vaccinees developed serum autologous tier 2 nAbs (ID50 titer, 1:28-1:8647) after two to three doses targeting C3/V5 and/or V1/V2/V3 Env regions by electron microscopy and mutated pseudovirus-based neutralization analyses. Trimer-specific, B cell-derived monoclonal antibody activities confirmed these results and showed weak heterologous neutralization in the strongest responder. Our findings demonstrate the clinical utility of the 3M-052-AF/Alum adjuvant and support further improvements of trimer-based Env immunogens to focus responses on multiple broad nAb epitopes.

HIV BG505 SOSIP.664 trimer with 3M-052-AF/alum induces human autologous tier-2 neutralizing antibodies.

Stabilized trimers preserving the native-like HIV envelope structure may be key components of a preventive HIV vaccine regimen to induce broadly neutralizing antibodies (bnAbs). We evaluated trimeric BG505 SOSIP.664 gp140, formulated with a novel TLR7/8 signaling adjuvant, 3M-052-AF/Alum, for safety, adjuvant dose-finding and immunogenicity in a first-in-healthy adult (n=17), randomized, placebo-controlled trial (HVTN 137A). The vaccine regimen appeared safe. Robust, trimer-specific antibody, B-cell and CD4+ T-cell responses emerged post-vaccination. Five vaccinees developed serum autologous tier-2 nAbs (ID50 titer, 1:28-1:8647) after 2-3 doses targeting C3/V5 and/or V1/V2/V3 Env regions by electron microscopy and mutated pseudovirus-based neutralization analyses. Trimer-specific, B-cell-derived monoclonal antibody activities confirmed these results and showed weak heterologous neutralization in the strongest responder. Our findings demonstrate the clinical utility of the 3M-052-AF/alum adjuvant and support further improvements of trimer-based Env immunogens to focus responses on multiple broad nAb epitopes. KEY TAKEAWAY/TAKE-HOME MESSAGES: HIV BG505 SOSIP.664 trimer with novel 3M-052-AF/alum adjuvant in humans appears safe and induces serum neutralizing antibodies to matched clade A, tier 2 virus, that map to diverse Env epitopes with relatively high titers. The novel adjuvant may be an important mediator of vaccine response.