Retinitis and deviant immune responses following intravitreal inoculation of HSV-1

Following anterior chamber inoculation of herpes simplex virus type 1 (HSV-1) into one eye of adult, immunocompetent BALB/c mice, an interesting pattern of ocular pathology and systemic immune responses emerges, characterized by destruction of the contralateral retina with sparing of the ipsilateral retina; and impairment of delayed hypersensitivity (DH) accompanied by intact humoral immunity to the virus. Experiments using animals inoculated via the intravitreal route revealed a different pattern of retinitis in the inoculated and in the uninoculated fellow eye following intravitreal inoculation of HSV-1. The retinitis in the inoculated eye results in localized, focal necrosis with concomitant preservation of the retinal architecture in areas juxtaposed to those in which retinal destruction occurs. The retinitis in the uninoculated contralateral eye is characterized by pan-retinal inflammation and subsequent loss of the architecture of the entire retina. Intravitreally inoculated animals exhibited virus-specific impairment of DH responses to HSV-1 but were capable of producing anti-HSV-1 neutralizing antibody. Impairment of DH response after inoculation of live HSV-1 suggests that intraocular processing of viral antigens occurs such that processed antigens are released systemically in a soluble form.