Differential induction of innate anti-viral responses by TLR ligands against Herpes simplex virus, type 2, infection in primary genital epithelium of women

Genital epithelial cells (GECs) are the first line of mucosal defense against sexually transmitted infections. We exploited the ability of GECs to mount innate immune responses, by using TLR ligands to induce anti-viral activity against Herpes simplex virus, type 2 (HSV-2). Primary cultures of GECs were grown to confluent, polarized monolayers and found to express different levels of mRNA for TLR1-10. Innate anti-viral responses against HSV-2 infection were determined following treatment with eight different TLR ligands. HSV-2 replication was significantly inhibited following treatment with ligands for TLR3, 5 and 9, while lipo-polysaccharide (LPS), a TLR4 ligand, failed to provide any protection. Biologically active interferon-beta and nitric oxide production by GECs correlated with anti-viral activity. Following treatment with TLR3 ligand Poly I:C, inflammatory cytokines were upregulated. Poly I:C treatment led to activation of downstream transcription factors including interferon regulatory factor-3 (IRF-3) and NFkappaB. Anti-viral responses induced by TLR ligands in GECs may provide a unique alternative to topical microbicides by enhancing body's own mucosal innate defense mechanisms against sexually transmitted viruses.