Sialodacryoadenitis in the rat: effects of immunosuppression on the course of the disease

Rats treated with prednisolone (PR) or cyclophosphamide (CY) and inoculated intranasally with sialodacryoadenitis (SDA) virus were compared with nonimmunosuppressed, inoculated rats. Histological changes in salivary and lacrimal glands, immunofluorescent microscopy of paraffin-embedded tissues, serum amylase levels, and antibody response showed little difference in the course and intensity of SDA in PR-treated and nonimmunosuppressed rats. In CY-treated rats, there was a delay in the onset of SDA, in the appearance of inflammatory cells in affected glands, and in the reparative process in the salivary and lacrimal glands. Viral antigen persisted longer in CY-treated rats than in PR-treated and nonimmunosuppressed rats. Antibody to SDA virus was not detected in CY-treated rats. The efficacy of immunosuppression by PR and CY was confirmed by the sheep erythrocyte agglutination procedure. Rats were immunosuppressed 4 weeks after inoculation with SDA virus. Histological examination of salivary and lacrimal glands, immunofluorescent microscopy, serum amylase values, and viral isolation studies did not reveal evidence of reactivation of a persistent viral infection or viral shedding. There is thus no evidence that SDA virus may persist as an inapparent infection after recovery from the disease..