Background: Specific mutations in VPR and V2 potentially restrict HIV-1 replication in macrophages. Such restriction could potentially limit HIV replication in long-term non-progressors (LTNP), thus accounting for low viral load and delayed progression to AIDS.
Objective: To examine whether a specific VPR phenotype (truncated versus non-truncated) correlates with disease progression and whether elongated V2 restricts viral replication in macrophages or alters viral tropism.
Methods: Sequence analysis was carried for VPR and V1-V3 env from four rapid progressors (RPs), six late progressors (LPs), and three LTNPs in cohort of HIV-1-infected homosexual men. The replication kinetics of sequential isolates was examined in primary CD4 cells and macrophages and coreceptor usage was determined by GHOST infection assays.
Results: No differences were found in the VPR protein from RP and LTNP isolates. Analysis of the V2 region revealed that all RPs maintained similar V2 lengths (40 aa), whereas LPs and LTNPs acquired additional amino acids (2-13 aa) in the V2 region. Coreceptor specificity revealed that RP switch from CCR5 to multiple coreceptor usage, whereas LTNPs maintained R5 viruses. Sequential isolates from each group revealed comparable replication efficiencies in both T-cells and macrophages, regardless of the V2 length or coreceptor utilization. In addition, cross-section analysis of six LTNPs from Australia revealed extended V2 with consistent usage of CCR5 coreceptor.
Conclusion: The present results suggest that acquisition of a V2 extension over time in HIV-1-infected LPs/LTNPs appears to correlate with maintenance of CCR5 usage among LTNPs. These findings may be important for a better understanding of the host interactions and disease progression.