Alterations in RANTES gene expression and T-cell prevalence in intestinal mucosa during pathogenic or nonpathogenic simian immunodeficiency virus infection

RANTES, a beta-chemokine, can suppress human immunodeficiency virus (HIV) a s well as simian immunodeficiency virus (SIV) infections in T-lymphocyte cu ltures in vitro. However, the association of RANTES levels in peripheral bl ood with viral loads and disease outcome in HIV infection has been inconclu sive. SIV-infected rhesus macaques were evaluated to determine whether RANT ES gene expression correlated with suppression of viral infection in intest inal lymphoid tissues. Intestinal tissues were obtained from rhesus macaque s infected with either pathogenic or nonpathogenic SIVmac variants at vario us stages of infection (primary acute, asymptomatic, and terminal). We exam ined the level of SIV infection (in situ hybridization), RANTES expression (quantitative competitive RT-PCR), and T-cell counts (immunohistochemistry) . The most pronounced increase in RANTES gene expression in intestinal tiss ues was observed in primary SIV infection, which correlated with the pathog enicity of the infecting virus and not the tissue viral loads. Our results demonstrated that in contrast to the occurrence of viral suppression by RAN TES in vitro, there was no direct correlation between high RANTES gene expr ession and suppression of viral loads in intestinal lymphoid tissues. Thus RANTES expression in the gut lymphoid tissue may not be a correlate for vir al suppression. However, RANTES gene expression in primary SIV infection ma y be part of early host immune response to viral infection. (C) 1999 Academ ic Press.