In vitro growth characteristics and heterogeneity of mouse hepatitis virus type 3

The in vitro virus yield of MHV3 reached 10(7) PFU/ml in mouse DBT cells infected with a virus suspension in HEPES-buffered medium containing DEAE-dextran. The virus titer was 10(6) PFU/ml in the presence of 10 micrograms actinomycin D/ml MHV3 growth in DBT cells gave three peaks of density (1.10--1.14 g/cm3, 1.18--1.20 g/cm3, and 1.25--1.31 g/cm3) in sucrose gradients. All these peaks retained infectivity.