Ex vivo Analysis of Herpes Simplex Virus Type 2 (HSV-2) Specific T Cells In The Human Female Reproductive Tract

Local mucosal cellular immunity is critical in providing protection to HSV-2 and vaccine strategies that target protective T cell responses to the genital mucosa are urgently needed. In order to characterize and quantitate HSV-2 reactive mucosal T cells, lymphocytes were isolated from endocervical cytobrushes and biopsies from 10 HSV-2 infected women and examined ex vivo for the expression of markers associated with tissue residency as well as functional memory T cell responses to HSV-2.  Cervical biopsies yielded higher total numbers of CD3+ lymphocytes compared to cytobrushes, total CD3+ lymphocytes from biopsies and cytobrushes were comprised predominantly of CD4+ T cells and in contrast to their circulating counterparts, cervix-derived CD4+ and CD8+ T cells expressed the tissue-specific markers CD69 and CD103.  Cervix-derived T cells were analyzed ex vivo for HSV-2 reactivity: 9 of the 11 cervical samples yielded sufficient cell numbers for analysis and of those, 8 contained HSV-2 specific CD4+/IFN-γ+ T cells (median 6.79%).  In contrast, only 5 of the cervical samples yielded sufficient numbers of CD8+ T cells for analysis and of those, only one contained HSV-2 specific CD8+/IFN-γ+ cells (1.08%).  Cervix-derived HSV-2 specific CD4+ T cells also expressed IL-2 and CD103 and were enriched in the cervix compared to the blood. The study of these mucosal T cells will be central to the elucidation of immune correlates of protection to HSV-2 and to the design and development of effective immune strategies preventing HSV-2 acquisition and reactivation.