IL18 and infection: Although all viruses increased the levels of IL-18 in hTCEpi cells compared to mock-infected hTCEpi cells, the virulent HSV-1 strains (17, McKrae, and KOS79) induced significantly higher levels of IL-18 early at 2 h post-infection compared to less-virulent HSV-1 strains (F, RE, KOS, and KOS63) (Figures 6A–D).