Genetic Variation of Neurotropic and Non-neurotropic Murine Coronaviruses

Abstract
The murine coronavirus strains MHV JHM, MHV 1, MHV 2, MHV 3 and MHV A59 were tested for their neurovirulence in weanling rats. The MHV JHM strain was highly neurovirulent for weanling rats; the other strains were not, or only slightly, neurovirulent. MHV 1 caused no lesions in weanling rats. The other strains (MHV 2, MHV 3 and MHV A59) induced predominantly subclinical infections in weanling rats as demonstrated by an increase of antibodies and inflammatory lesions in the liver. Analysis of these strains by cross-neutralization revealed variable degrees of antigenic relationship between these viruses, which were not related to their neurovirulence. Analysis of the T1-RNase-resistant oligonucleotides of the virion RNA of these strains showed that the highly neurovirulent, MHV JHM strain, differed significantly in its nucleotide sequence from the other less neurovirulent strains.