Long-term Experience and Outcomes of Programmatic Antiretroviral Therapy for Human Immunodeficiency Virus Type 2 Infection in Senegal, West Africa.

BACKGROUND: Programmatic treatment outcome data for people living with human immunodeficiency virus type 2 (HIV-2) in West Africa, where the virus is most prevalent, are scarce. METHODS: Adults with HIV-2 initiating or receiving antiretroviral therapy (ART) through the Senegalese national AIDS program were invited to participate in this prospective, longitudinal observational cohort study. We analyzed HIV-2 viral loads, CD4 cell counts, antiretroviral drug resistance, loss to follow-up, and mortality. We also examined changes in treatment guidelines over time and assessed progress toward the Joint United Nations Programme on HIV/AIDS (UNAIDS) 90-90-90 targets for HIV-2. RESULTS: We enrolled 291 participants at 2 sites for 926.0 person-years of follow-up over 13 years. Median follow-up time was 2.2 years per participant. There were 21 deaths reported (7.2%), and 117 individuals (40.2%) were lost to follow-up, including 43 (14.7%) who had an initial visit but never returned for follow-up. CD4 counts and HIV-2 viral suppression (< 50 copies/mL) at enrollment increased over calendar time. Over the study period, 76.7% of plasma viral loads for participants receiving ART were suppressed, and median CD4 gain was 84 cells/µL in participants' first 2 years on study. Since the UNAIDS 90-90-90 strategy was published, 88.1% of viral loads were suppressed. Fifteen percent of patients experienced virologic failure with no known resistance mutations, while 56% had evidence of multiclass drug resistance. CONCLUSIONS: Participants in the Senegalese national AIDS program are initiating ART earlier in the course of disease, and more modern therapeutic regimens have improved outcomes among those receiving therapy. Despite these achievements, HIV-2 treatment remains suboptimal, and significant challenges to improving care remain.

Role of human immunodeficiency virus (HIV)-specific T-cell immunity in control of dual HIV-1 and HIV-2 infection.

Progressive immune dysfunction and AIDS develop in most cases of human immunodeficiency virus type 1 (HIV-1) infection but in only 25 to 30% of persons with HIV-2 infection. However, the natural history and immunologic responses of individuals with dual HIV-1 and HIV-2 infection are largely undefined. Based on our previous findings, we hypothesized that among patients with dual infection the control of HIV-1 is associated with the ability to respond to HIV-2 Gag epitopes and to maintain HIV-specific CD4(+) T-cell responses. To test this, we compared the HIV-specific ex vivo IFN-gamma enzyme-linked immunospot (ELISPOT) assay responses of 19 dually infected individuals to those of persons infected with HIV-1 or HIV-2 only. Further, we assessed the functional profile of HIV Gag-specific CD4(+) and CD8(+) T cells from nine HIV dually infected patients by using a multicolor intracellular cytokine staining assay. As determined by ELISPOT assay, the magnitude and frequency of IFN-gamma-secreting T-cell responses to gene products of HIV-1 were higher than those to gene products of HIV-2 (2.64 versus 1.53 log(10) IFN-gamma spot-forming cells/10(6) cells [90% versus 63%, respectively].) Further, HIV-1 Env-, Gag-, and Nef- and HIV-2 Gag-specific responses were common; HIV-2 Nef-specific responses were rare. HIV-specific CD4(+) T helper responses were detected in nine of nine dually infected subjects, with the majority of these T cells producing gamma interferon (IFN-gamma) and tumor necrosis factor alpha (TNF-alpha) and, to a lesser extent, interleukin-2. The HIV-1 plasma viral load was inversely correlated with HIV-2 Gag-specific IFN-gamma-/TNF-alpha-secreting CD4(+) and HIV-2 Gag-specific IFN-gamma-secreting CD8(+) T cells. In conclusion, the T-cell memory responses associated with containment of single HIV-1 and HIV-2 infection play a similar significant role in the immune control of dual HIV-1 and HIV-2 infection.