INFECTIVITY, DISEASE PATTERNS, AND SEROLOGIC PROFILES OF REOVIRUS SEROTYPE-1, SEROTYPE-2, AND SEROTYPE-3 IN INFANT AND WEANLING MICE

The oronasal median infectious doses of reovirus serotypes 1, 2, and 3 were established in infant and weanling Sencar mice on the basis of d isease expression and seroconversion. Infant mice were susceptible to infection with low doses of all three serotypes, whereas weanling mice were comparatively resistant to infection. Uniform transmission of vi rus to cagemates or mothers of infants did not occur, indicating low c ontagiousness of all three virus serotypes. The comparative susceptibi lity of 2-day-old Sencar mice to disease was examined following oronas al inoculation with reovirus 1, 2, or 3. Tissues were collected on day s 3,5,7,9,14,16, and 21 after inoculation for virus isolation, histolo gic examination, and serologic analysis. Disease patterns in infant mi ce were distinctly different among reovirus serotypes. Reovirus 3 indu ced severe disease, with focal myocarditis, hepatitis, diffuse encepha litis, and generalized lymphoid depletion, whereas reovirus 1 induced a similar pattern, but much milder disease. In contrast, reovirus 2 in duced mild transient enteritis without lesions in other organs. Sera f rom experimentally infected mice were tested in virus serotype-specifi c enzyme immunoassays. Cross reactivity of antibody among the three vi rus serotypes was found, but antibody titers were always highest with the homologous antigen. These studies confirm that infant laboratory m ice are susceptible to infection with all three serotypes of virus; we anling mice are comparatively resistant to infection and disease; the viruses induce different patterns of disease in infant mice; and infec ting virus serotypes can be distinguished serologically by enzyme immu noassay.