MOLECULAR AND BIOLOGICAL CHARACTERIZATION OF NEW STRAINS OF MURINE CYTOMEGALOVIRUS ISOLATED FROM WILD MICE

Studies of the prevalence of antibody to murine cytomegalovirus (MCMV) in free-living wild mice (Mus domesticus) trapped in diverse regions of Australia and on a sub-Antarctic island indicated that 90% of 468 m ice had serum antibody to MCMV. Twenty-six field isolates of MCMV were plaque-purified from salivary gland extracts of representative seropo sitive mice. These isolates varied considerably in their ability to re plicate in the salivary glands of weanling BALB/c mice with 9 of 15 fa iling to reach significant titres in this organ and the titres of the remaining 6 strains varying by at least 100-fold. The high frequency o f restriction fragment length polymorphisms observed suggests widespre ad genetic heterogeneity exists among the strains. This observation wa s mirrored at the polypeptide level by Western blot analyses with poly clonal antisera to MCMV. The isolation in this study of four genetical ly distinct strains of MCMV from a single wild mouse and several strai ns from other individual mice demonstrates that multiple infections wi th MCMV may be commonplace in wild mice.