IN VITRO INTERACTION OF MOUSE HEPATITIS VIRUS AND MACROPHAGES FROM GENETICALLY RESISTANT MICE : II. BIOLOGICAL CHARACTERIZATION OF A VARIANT VIRUS MHV(C(3)H) ISOLATED FROM STOCKS OF MHV(PRI)

Shif, Ilan; Bang, Frederik B.

Two interpretations concerning the emergence of MHV(C3H) are possible. The variant may be a constantly occurring mutant, or its appearance may be in some way dependent upon the host cell itself which ingests and protects the MHV(PRI). In favor of the selection of a constantly occurring true mutant is the fact that different stocks of virus differed in the tendency to give rise to the variant, and that a real decrease in the appearance of the variant was produced by cloning the original. A search was therefore made in the MHV(PRI)-infectious material for some factor which would increase the conversion of wild virus to the variant. When UV-irradiated MHV(PRI), reduced in the titer by 100-fold, was put on C3H macrophages or was combined with low multiplicities of nnirradiated virus before putting it on macrophages, no destruction occurred. The same virus which was not UV irradiated (control) did cause a delayed destruction of the C3H ceils.