RESUMEN
Elimination of an enzootic infection of mouse hepatitis virus (MHV) from a large population of genetically engineered mice was accomplished by selecting seropositive, non-infective breeders for a newly restored MHV-free breeding colony. An ELISA was used to test for the presence of MHV-specific antibody, and TaqMan reverse transcriptase-polymerase chain reaction (RT-PCR) analysis was used to detect MHV in the feces. After 10 weeks of intentional exposure, approximately 30% of mice with MHV antibodies continued to shed MHV in the feces. A natural transmission study was conducted to validate that positive fecal RT-PCR results indicated presence of infective virus. Sentinel results from the re-instituted breeding colony indicated that MHV was successfully eliminated by use of RT-PCR analysis for selection of non-infective mice.