CHARACTERIZATION OF A VIRUS VARIANT PRODUCED BY L-CELLS PERSISTENTLY INFECTED WITH LYMPHOCYTIC CHORIOMENINGITIS VIRUS

Continuous cultivation of murine L cells infected with lymphocytic cho riomeningitis virus strain Armstrong leads to production of L(Arm) cel ls, which produce a predominantly cell-associated attenuated variant, the L(Arm) virus. The relatively few infectious particles that are rel eased have lost the ability to form plaques on L cells and to cause il lness in mice even if inoculated intracerebrally. Based on equal prote in M(r)s, antigenicity and protein kinase activity, essentially identi cal results were obtained for the purified Armstrong and L(Arm) viruse s. There was also no difference in production and release of particles with the potential to cause homologous interference. Such particles c onsisted of two types, one of which was highly susceptible to u.v.-irr adiation, the other was highly resistant. In the case of the L(Arm) vi rus interfering particles, it appears that the u.v.-irradiation-suscep tible forms represented infectious virus. Purified L(Arm) virus partic les contained considerable quantities of subgenomic forms of(small) S- and (large) L-RNA and their complementary counterparts, which all app eared to be replicated autonomously in an unenriched manner.