Characterization of mouse parvovirus infection by in situ hybridization.

Infection of young adult BALB/cByJ mice with mouse parvovirus-1, a newly recognized, lymphocytotropic, nonpathogenic parvovirus, was examined by in situ hybridization. Virus appeared to enter through the small intestine and was disseminated to the liver and lymphoid tissues. Strand-specific probes detected virion DNA in a consistently larger number of cells than replicative forms of viral DNA and/or viral mRNA. The number of signal-positive cells in the intestinal mucosa, lymph nodes, spleen, and thymus increased through day 10 after oral inoculation but decreased after seroconversion. Positive cells were still detected, however, in peripheral lymphoid tissues of mice examined at 9 weeks postinoculation. The results underscore the need to assess potential effects of persistent mouse parvovirus-1 infection on immune function in mice.