Characterization of a variant virus isolated from neural cell culture after infection of mouse coronavirus JHMV

Our previous experiments showed that a variant virus with a larger envelope glycoprotein encoded by a larger mRNA3 (cl-2) multiplied predominantly in the brain of rats after wild type (wt) JHMV infection (F. Taguchi, S. Siddell, H. Wege, and V. ter Meulen, 1985, J. Virol., 54, 429–435). We could isolate similar but not identical variant virus after infection of cultured neural cells from rat brain with wt JHMV (designated CNS virus), which also had a larger mRNA3 and produced larger envelope E2 glycoprotein in infected cells. CNS virus multiplied to a higher degree in cultured astrocytes from rat than wt JHMV and cl-2. During infection with these variant viruses in neural cells, virus populations generated did not change, in contrast to consistent selection of viruses with larger mRNA3 after wt JHMV infections. CNS virus produced abundant mRNA2a as well as 65K glycoprotein while the productions of both were trace in cl-2 infected cells. The present experiments, together with our previous observation, suggest that the larger E2 glycoprotein may be of importance for the replication in rat brain cells.