Dual role of the immune response in street rabiesvirus infection of mice.

The cellular and humoral immune responses of mice to footpad injection of salivary gland suspensions of street rabiesvirus were investigated. Suppression of these responses with cyclophosphamide both increased the overall mortality rate from (50 to 100%) and delayed onset of disease signs and death for 1 to 2 weeks. Despite the absence of disease signs in these immunosuppressed animals, virus was present in the central nervous system, as shown by fluorescent-antibody staining of corneal epithelium. The onset of paralysis after limited immunosuppression was temporally related to a return to immune responsiveness, and passive transfer of homologous immune serum to infected immunosuppressed animals brought about their early paralysis and death. These findings indicate the importance of the immune response in the pathogenesis of street rabiesvirus infection.