Gamma/delta T cell mRNA levels decrease at mucosal sites and increase at lymphoid sites following an oral SIV infection of macaques

The oral and esophageal mucosa have been identified as possible sites of HIV/SIV entry following oral infection. Here, gamma/delta (γδ) T cells, a multi-functional T cell subset, were assessed at oral/ esophageal mucosa and lymphoid sites at the earliest times (1-14 days) post-oral SIV inoculation utilizing quantitative RT-PCR. During these earliest times post-infection, decreased γδ TCR mRNA levels were observed at the oral gingiva and esophageal mucosa, while increased levels were observed within regional lymph nodes (cervical and retropharyngeal). Higher lymph node γδ TCR levels were associated with increased mRNA expression of the lymphoid homing chemokine/receptor (CCL21/CCR7) pair in these lymph nodes. In contrast to γδ TCR levels, CD4 mRNA expression remained relatively stable through 4 days post-infection, and depletion of CD4 T cells was only evident after 7 or 14 days post-infection. The decrease of γδ T cell mRNA from mucosal sites and the corresponding increase at lymphoid sites suggest a rapid redistribution of these immune cells at these earliest times post-SIV infection.