T‐helper reactivity to simian immunodeficiency virus gag synthetic peptides in human immunodeficiency virus type 2 infected individuals

Abstract

West African populations are infected with divergent strains of human immunodeficiency virus type 2 (HIV2), some of which are closely related to simian immunodeficiency virus (SIV) and it has been postulated that the HIV2 epidemic might have arisen by cross-species spread of SIV into the human population in West Africa. To gain some insight into the possible basis for cross protection between these two closely related viruses, the T-helper responses to 15 synthetic peptides from SIV gag synthetic peptides were investigated in seven HIV2-infected subjects and in seven healthy controls. Significant reactivity to at least one of the synthetic peptides tested was found in all patients and a statistically significant correlation between CD4+ lymphocyte absolute numbers and the number of reacting peptides was observed. A marginal lymphocyte reactivity was found in two of the healthy controls studied. In conclusion, this preliminary evidence that HIV2-infected patients exhibit T-cell responses to SIV gag peptides suggests that both viruses share t-helper epitopes in the gag viral region and raises the possibility of cross protection between SIV and HIV2 which may be relevant for HIV2 vaccine research based on closely related retroviruses.

Gag-Specific CD4+T-Cell Frequency Is Inversely Correlated with Proviral Load and Directly Correlated with Immune Activation in Infection with Human Immunodeficiency Virus Type 2 (HIV-2) but Not HIV-1

“…Moreover, other studies have shown that PBMC isolated from HIV-2-infected individuals respond to simian immunodeficiency virus recombinant proteins and peptide pools, both in terms of proliferation (21,22) and cytokine production (2). Overall, these data suggest that HIV-2-specific CD4 responses may feature a degree of flexibility similar to that reported for their CD8 counterparts (16).…”

“…HIV-2-specific CD4 ϩ T cells have been less well characterized (6,7,21,22,30), though a better preserved proliferative capacity has been shown (6).…”

Polyfunctional T cell responses are a hallmark of HIV‐2 infection

“…The HIV-specific CD4 + T cell response in chronic infection is thus either entirely absent, severely impaired, or skewed towards a population that produces IFN-c only [17][18][19]. In contrast, HIV-specific CD4 + T cells are more frequent in chronic HIV-2 infection [13,[20][21][22]. Recently, we assessed the CD4 + T cell response to HIV-2 in terms of cytokine production and proliferative capacity [14].…”

Human immunodeficiency virus (HIV)-2-specific T lymphocyte proliferative responses in HIV-2-infected and in HIV-2-exposed but uninfected individuals in Guinea-Bissau

“…Half of the HIV-2-infected individuals studied here had a positive HIV-2-specific T cell proliferative response. This is in line with data reported by Pinto et al ., who studied T helper cell reactivities to SIV synthetic peptides and HIV-2 recombinant antigens [45,46]. In contrast, in early studies of HIV-1-infected patients, virus-specific lymphocyte-proliferative responses were usually weak [57,58].…”

“…Pinto et al . reported T helper reactivity in HIV-2-infected individuals to recombinant HIV-2 and HIV-1 antigens and to synthetic SIV peptides [45,46]. HIV-2-exposed uninfected (EU) individuals have been studied only once before, in six female commercial sex workers (CSW) in The Gambia, two of whom had HIV-2-specific immune responses [8].…”