Persistent Rubella Virus Infection in Hamster Lung Cells

Cell cultures were established from the lungs of hamsters which had been previously infected intranasally with the judith strain or the HPV 77 vaccine strain of rubella virus. The hamster lung cells were cultured in vitro and produced infective rubella virus for at least 12 subcultures. The persistently infected cells had a lag phase of 48 hr compared to a lag phase of 24 hr in uninfected cells. Morphologically, the persistently infected cells were indistinguishable from uninfected cells. Treatment of the persistently infected cells with 25 µg./ml. amantadine, 0.15 µg./ml. actinomycin D or 250 µg./ml. hydrocortisone had no detectable effect on rubella virus yields. Infective cell counts indicated that between 5 and 50% of hamster lung cells were releasing infective rubella virus. The persistently infected cells were resistant to challenge with vaccinia virus and, to a lesser degree, with herpes simplex virus.