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.

In addition, plaques of MHV(C3H) were apparently initiated by single in- fectious particles since a one-hit dose response curve was obtained on PRI as well as on CaI-I monolayers (Table III ). In addition, lVIII-IV(CsH), the strain which had been isolated from macrophage cultures, killed both C3I-I and PRI adult mice and also Swiss albino mice (Table IV) . However, the effects of the new virus on the different strains of mice were not identical: (a) Adult PRI mice succumbed to the virus 2-3 days after intraperitoneal inoculation, but adult C3H and Swiss albino mice died only after 4 or more days; (b) High titers of undiluted MHV(C3H) killed all injected PRI mice, but only one third of C3H and Swiss albino mice. * C3H cultures were inoculated with 0.1 ml of each of the above viral dilutions. The tubes were incubated at 37°C and examined daily for 8 days. Cultures which showed destruction before or on the 8th day, were removed and frozen. (No culture showed destruction before day 3.) All of the remaining 64 tube cultures and the 26 previously frozen cultures were subjected to 5 rapid cycles of freezing and thawing. The fluid was then inoculated into 5 C3H tube cultures each. Complete destruction in 48 hr resulted in all cultures inoculated with fluid from tubes where there had originally been delayed destruction. No destruction was seen in 2 wk of observation in cultures inoculated with fluid from C3H cultures that themselves showed no destruction.