A large proportion of the patients at the clinic were lost to follow-up. The main reason for this was found to be the geographic mobility of the population in Guinea-Bissau.

Background For unknown reasons, HIV-2 is less pathogenic than HIV-1, and HIV-2 induced immunodeficiency may be different from that caused by HIV-1. Previous immunological studies have hinted at possible shifts in both T and B-cell subsets, which we aimed to characterize further. Methods From an HIV clinic in Guinea-Bissau, 63 HIV-2, 83 HIV-1, and 26 HIV negative participants were included. All HIV infected participants were ART naïve. The following cell subsets were analysed by flow cytometry; T cells (maturation and activation), regulatory T cells, and B cells (maturation and activation). Results After standardizing for sex, age, and CD4+ T cell count HIV-2 had 0.938 log10 copies/mL lower HIV RNA levels than the HIV-1 infected patients. Whereas T-cell maturation and regulatory T-cell profiles were similar between patients, HIV-2 infected patients had higher proportions of CD8+CD28+ and lower proportions of CD8+PD-1+ T cells than HIV-1 infected patients. This finding was independent of HIV RNA levels. HIV-2 was also associated with a more preserved proportion of naïve B cells. Conclusion HIV-2 is characterized by lower viral load, and lower T-cell activation, which may account for the slower disease progression.

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