A comparison of recurrent and primary herpes simplex keratitis in NIH inbred mice

Herpes simplex virus (HSV) infection is one of the leading causes of corneal blindness. This study compared the clinical, virologic, and immunopathologic features of primary and recurrent murine models of herpes simplex keratitis (HSK) in the National Institutes of Health (NIH) inbred mouse strain. Primary infection resulted in multiple epithelial dendrites, followed by diffuse stromal opacification, symptoms that do not mimic what is seen in human HSK. In contrast, recurrent infection presented clinical features that included microdendrites, focal stromal opacities, disciform endotheliitis, and corneal neovascularization, which were similar to those observed in human disease. Immunohistochemical characterizations indicated that the number and duration of T cells and macrophages in recurrent HSK resemble those observed in primary disease. Results also indicated that the amount of infectious virus detected in the cornea during primary and recurrent disease was similar. However, when corneas were stained for HSV-I antigens, mice with primary HSK displayed diffuse HSV antigen expression throughout the cornea, whereas HSV antigens were more focally distributed in recurrent disease. These data suggest that the clinical differences between the recurrent and primary herpetic keratitis may, in part, reflect the different distribution of HSV-1 antigens within the cornea.