Peripheral blood CD4 and CD8 double-positive T cells of rhesus macaques become vulnerable to Simian Immunodeficiency Virus by in vitro stimulation due to the induction of CCR5.

In vivo Simian Immunodeficiency Virus (SIV) challenge of macaques demonstrated the earlier disappearance of CD4 and CD8 double-positive (DP) T cells than CD4 single-positive T cells, although its mechanism remains unclear. Here we found that peripheral DP T cells were readily induced to express CCR5, a secondary receptor for SIV, by in vitro stimulation with either concanavalin A or anti-CD3/CD28 monoclonal antibodies. Activated DP T cells were more vulnerable to SIV infection, indicating that the ability of DP T cells to readily express CCR5 after activation may hasten DP T cell death by SIV infection in vivo.