Isolation of a murine hepatitis virus from Swiss mice treated with antilymphocyte serum

In an attempt to transmit feline malignant lymphoma to mice, a murine hepatitis virus (MHV) was accidentally recovered from conventionally reared Swiss mice receiving prolonged treatment with antilymphocyte serum. In these mice, the virus did not require concomitant infection withEperythrozoon coccoides to produce disease. Tests for antibodies against a variety of viruses were performed on serum from control colony mice and mice that recovered from experimental infection as well as on serum pooled from vaccinated and non-vaccinated mice challenged with the recovered agent. Antibodies to the MHV complement fixing (CF) antigen(s) were demonstrated in only the last mentioned serum. Mice harbouring a hepatitis virus may thus be tolerant to their CF antigen(s) in a situation analogous to oncornavirus infection of their natural hosts. The liver pathology was that of a confluent focal-type necrosis resembling that produced by certain other MHV strains. We have labelled this newly isolated virus MHV (Swiss-Cape Town), abbreviated to MHV (S-CT).