Characterization of Sex Differences in Ocular HSV-1 Infection and Herpes Stromal Keratitis Pathogenesis of Wild Type and Herpesvirus Entry Mediator Knockout Mice

ABSTRACT Sex differences related to immune response and inflammation play a role in the susceptibility and pathogenesis of a variety of viral infections and disease (S. L. Klein, Bioessays 34:1050-9, 2012). Herpes simplex virus type 1 (HSV-1) causes chronic inflammatory disease in the cornea, an immune privileged tissue, resulting in irreversible damage and blindness in affected individuals (A. Rowe, A. St Leger, S. Jeon, D. K. Dhaliwal, J. E. Knickelbein, and E. Vilain, Prog Retin Eye Res 32:88-101, 2013). Our research focuses on the role of Herpes Viral Entry Mediator (HVEM) as an immune regulator during ocular HSV-1 infection. Mice lacking HVEM (HVEM KO) exhibit lower immune cell infiltrates and less severe ocular disease in the cornea compared to wild type (WT) mice. As sex differences contribute to pathogenesis in many inflammatory diseases, we tested sex as a biological variable in the immune response to HSV-1 infection and Herpes Stromal Keratitis pathogenesis (HSK). Adult male and female WT and HVEM KO mice were inoculated with HSV-1 via corneal scarification and monitored daily for disease course. Viral titers and immune cell infiltrates were collected and analyzed. Our results indicate no significant difference in viral titers in tear film or affected tissues; immune cell infiltration; or clinical symptoms between males and females of either genotype. These results suggest that sex is not a significant biological variable in this experimental model, and that male and female mice can similarly be used in studies of ocular HSV-1 pathogenesis. IMPORTANCE Sex hormones have only recently been considered as an important factor for the development of certain diseases and as such should continue to be considered as a biological variable. Ocular Herpesvirus Type 1 (HSV-1), and the resulting Herpes Stromal Keratitis, is the leading cause of infectious blindness worldwide. We compared ocular HSV-1 infection and pathogenesis between sexes and found no significance difference between male and female wild type mice or herpesvirus entry mediator knockout mice. Therefore, male and female mice can be used interchangeably in studying ocular HSV-1 pathogenesis.