Identification of novel murine parvovirus strains by epidemiological analysis of naturally infected mice.

Random-source DNA samples obtained from naturally infected laboratory mice (n=381) were evaluated by PCR and RFLP analysis to determine the prevalence of murine parvovirus strains circulating in contemporary laboratory mouse colonies. Mouse parvovirus (MPV) was detected in 77% of samples, Minute virus of mice (MVM) was detected in 16% of samples and both MVM and MPV were detected in 7% of samples. MVMm, a strain recently isolated from clinically ill NOD-mu chain knockout mice, was detected in 91% of MVM-positive samples, with the Cutter strain of MVM (MVMc) detected in the remaining samples. The prototypic and immunosuppressive strains of MVM were not detected in any of the samples. MPV-1 was detected in 78% of the MPV-positive samples and two newly identified murine parvoviruses, tentatively named MPV-2 and MPV-3, were detected in 21 and 1% of the samples, respectively. The DNA sequence encompassing coding regions of the viral genome and the predicted protein sequences for MVMm, MPV-2 and MPV-3 were determined and compared with those of other rodent parvovirus strains and LuIII parvovirus. The genomic organization for the newly identified viral strains was similar to that of other rodent parvoviruses, and nucleotide sequence identities indicated that MVMm was most similar to MVMc (96.1%), MPV-3 was most similar to hamster parvovirus (HaPV) (98.1%) and MPV-2 was most similar to MPV-1 (95.3%). The genetic similarity of MPV-3 and HaPV suggests that HaPV epizootics in hamsters may result from cross-species transmission, with mice as the natural rodent host for this virus.