Infant rats are susceptible to persistent rat virus (RV) infection, but risk of persistent infection after prenatal exposure to virus is unclear. We examined this aspect of RV infection in the progeny of dams inoculated with virus during or prior to pregnancy. Sprague-Dawley (SD) dams were infected during pregnancy (gestation day 9) by oronasal inoculation with 105 TCID50 of the UMass strain of RV. SD rats were infected prior to pregnancy by oronasal inoculation of twoday-old females with 102 TCID50 of RV-UMass, which induced persistent infection. They were mated to non-immune males after reaching sexual maturity. Rats were assessed for RV infection by virus isolation, in situ hybridization, contact transmission, or serologic testing. The progeny of dams inoculated with virus during gestation had high prevalence of infection through postpartum week 9 (9 of 12 rats were virus positive at week 3, and 7 of 10 were virus positive at week 9). Additionally, 2 of 10 rats were virus positive at least through postpartum week 15. The progeny from persistently infected, seropositive dams had no evidence of infection and did not transmit infection to contact sentinels. However, 12 dams were virus positive at necropsy and 9 had transmitted infection to their breeding partners. These results indicate that prenatal infection in non-immune dams can lead to RV persistence in their progeny. By contrast, the progeny of persistently infected dams are protected from infection, presumably by maternal antibody, although their dams can transmit infection to their breeding partners.
Comparative Medicine (CM), an international journal of comparative and experimental medicine, is the leading English-language publication in the field and is ranked by the Science Citation Index in the upper third of all scientific journals. The mission of CM is to disseminate high-quality, peer-reviewed information that expands biomedical knowledge and promotes human and animal health through the study of laboratory animal disease, animal models of disease, and basic biologic mechanisms related to disease in people and animals.
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