The effect of nonspecific immune stimulation on the recurrence rate of herpetic keratitis in rabbits.

Cellular immunity is of primary importance in resistance to virus infection. In this study, 75 rabbits were immunized with live BCG, 75 rabbits were immunized with Staphylococcus aureus, and 75 rabbits were injected with saline. Two weeks after immunization the corneal epithelium of both eyes was infected with McKrae strain herpes virus, and five weeks after immunization the rabbits were skin tested with old tuberculin or staphylococcus to ascertain their immune status. The corneas were observed under the slit lamp for recurrent epithelial herpes from day 52 through day 84 after immunization. During the second week of observation the group immunized with BCG had statistically significantly fewer recurrences than the saline-injected control group. The data for the BCG group during the remainder of the observation period, and for the SPL immunized group, were not statistically distinguishable from the control group. These experiments indicate that nonspecific immune stimulation provides little protection against recurrent herpetic infection. It is possible that manipulation of dosage and timing could enhance this effect.