抄録
Two mutants were isolated from YH strain. One (L) produces the large plaques on GMK cells in contrast with the small plaque formation by parent virus (S). The other (G) produces larger plaques than L mutant with the formation of multinucleated giant cells. The mutants breed true in the proliferation in RK or GMK cells, but the parent S virus breeds true only when it was passaged in RK cells and not in GMK cells. They are different in growth in GMK cells, and the failure of maintenance of the properties of S virus in GMK cells is due to the greater yield of L mutant in this cells. Although no antigenic difference is detected among them, Gmutant is significantly more labile to heat than the others.
