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.

There was a 90-99.9 % inhibition in MHV(C3H) yields (Table VIII) Interferon Production #~ C3H Macrophage Cultures.--It has been shown by several authors (4-7) that cultured macrophages are a good source of interferon even when unstimulated by viruses or by bacterial endotoxin. Therefore, in order to try to explain the interference found here, it was essential to search for interferon in this system. C3H cultures supplemented with either Chang's or Eagle's medium were infected with undiluted preparations of MHV(PRI). 20 hr after incubation at 37°C, the culture fluids were collected in a dialyzing bag. The bag was kept in a cold KC1-HCI buffer (pH 2) and after three changes transferred to phosphate buffer of neutral pH. The capacity of fluids to reduce the plaque titer of vesicular stomatifis virus 3 on L cell monolayers was tested. Monolayers of L cells were grown in plastic Petri dishes and covered with infected or normal C3H culture fluids. 24 hr later the plates were infected with 100 plaque-forming units (pfu) of vesicular stomafitis virus. The plaques were counted 2 days later after additions of 1 : 10,000 neutral red (Table IX) .