Role of IFN-alpha/beta signaling in the prevention of genital herpes virus type 2 infection.

This study has shown that IFN-alpha/beta signaling is crucial for combating primary herpes simplex virus type 2 (HSV-2) infection and for responding to immunotherapy using ligands to TLR3, 7 and 9, but not for vaccine-induced immunity. Both genital viral replication and the disease progression were enhanced in HSV-2-infected mice lacking the IFN-alpha/beta receptor (IFN-alpha/betaR-/-). IFN-alpha/betaR-/- mice were, however, able to mount a normal HSV-2-specific Th1 response and acquired sterilizing immunity following vaccination. Anti-viral treatments using agonists to TLR3, 7 and 9 by administration of synthetic dsRNA, imiquimod and oligonucleotides containing unmethylated CpG motifs, respectively, were strongly dependent on IFN-alpha/beta receptor signaling for their efficacy. Even though all treatments had a weak impact on local vaginal viral replication in infected IFN-alpha/betaR-/- animals, they did not affect disease progression or mortality in these animals as opposed to wild type controls where all three treatments reduced viral replication as well as disease severity and mortality. Lack of IFN-alpha/betaR signaling also blocked production of IFN-gamma and TNF-alpha in response to TLR9 activation. These studies have shown that IFN-alpha/beta receptor signaling is important for multiple events in the anti-viral defense.