- HIV-2 had lower HIV RNA levels and a higher proportion of naïve B-cells than HIV-1 infected patients.
- HIV-2 was characterized by higher proportions of CD8+CD28+ and lower proportions of CD8+PD-1+ T-cells than HIV-1 infection.
- Findings may partly explain why HIV-2 is less pathogenic and develop more slowly than HIV-1.
In a cross-sectional study, 63 HIV-2 (47 viremic and 16 aviremic), 83 HIV-1, and 26 HIV negative individuals were enrolled from an HIV clinic at Hospital Nacional Simão Mendes in Bissau, Guinea-Bissau. All infected participants were ART naïve.
The aim of the authors was to further understand the importance of HIV-2 RNA levels and immune perturbations in HIV-1 and HIV-2 infection. Indeed, as known, HIV-2 is less pathogenic than HIV-1, and HIV-2 induced immunodeficiency may be different from that caused by HIV-1.
After standardizing for sex, age and CD4+ T cell count, HIV RNA was lower for HIV-2 than for HIV-1 infected patients (p
Flow cytometry was used to analyze T-cells (maturation, activation and regulation) and B-cells (maturation and activation). In adjusted analysis, there was no difference in T-cell maturation between HIV-1 and HIV-2.
T-cell regulation (Tregs-profiles) was perturbed in HIV infected patients, but no difference was observed between HIV-1 and HIV-2.
Both HIV types were associated with an increased proportion of T-cells positive for activation markers. Interestingly, HIV-2 infected patients had higher proportions of CD8+CD28+ (p=0.008) and lower levels of CD8+PD-1+ T cells (p=0.001) than HIV-1 infected patients, independently from HIV RNA levels. This may result in more effective CD8+ T-cell responses to better control viral replication and slow CD4+ T cell decline.
Finally, in line with previous studies, the authors reported differences in B-cells. HIV-2 infected patients had a higher proportion of naïve B-cells among patients with CD4+ T-cell count below 350 cells/µL (p=0.001). HIV-1 and HIV-2 had a similarly high proportion of CD21low B-cells.
Although the reasons remain unknown, the lower viral load and the differences of T and B-cell phenotype between HIV types reported in this study may help to explain why HIV-2 has a slower disease progression than HIV-1 infected patients.