Physico-Chemical Properties of Mouse Hepatitis Virus (MHV-2) Grown on DBT Cell Culture

Abstract

Some properties of a strain of mouse hepatitis virus, MHV‐2, grown on DBT cells were determined using a plaque assay on the cells. Viral growth was not inhibited by the presence of actinomycin D or 5‐iodo‐2‐deoxyuridine. MHV‐2 was completely inactivated by ether, chloroform, sodium deoxycholate or beta‐propiolactone, but showed a moderate resistance to trypsin. Heating at 56 C for 30 min did not completely abolish the virus infectivity. The virus was stable after heating at 50 C for 15 min in 1m‐MgCl2 or 1m‐MgSO4 as well as at 37 C for 60 min at pH 3.0 to 9.0. Infectivity was decreased to 1/100 and 1/400 after storing at 4 C for 30 days and 37 C for 24 hr, respectively. The virus passed through a 200‐nm but not a 50‐nm Sartorius membrane filter. The buoyant density of MHV‐2 was 1.183 g/cm3 in sucrose gradient, and the fraction contained coronavirus‐like particles measuring 70 to 130 nm in diameter. Survival rate was 10% after exposure to ultraviolet at 150 ergs/mm2. Freezing and thawing or sonication at 20 kc for 3 min did not affect the virus titer. No hemagglutinin was demonstrable with red blood cells of the chicken, Japanese quail, mouse, rat, hamster, guinea pig, sheep, bovine or human.