Differences in natural and recombinant interferon for herpes keratitis in two animal models.

Natural human leukocyte interferon (natural HuIFN-alpha) and recombinant leukocyte A interferon (recombinant A HuIFN-alpha) were tested for prophylactic and/or therapeutic effects in reducing the severity of keratitis in rabbit and monkey eyes infected with McKrae strain herpesvirus. The results showed that the two interferons acted differently in the rabbit eye; combined prophylactic and therapeutic administration of natural interferon mitigated the disease, while recombinant interferon had no effect. In monkeys, the two interferons acted similarly. Combined prophylactic and therapeutic administration reduced disease findings, while therapeutic administration alone had no effect. Thus, studies in rabbits are not accurate predictors of primate study results; whether or not nonhuman primate results can be extrapolated to humans remains to be seen.