[Parotitis virus persistence in cell cultures of human origin]

Chronic infection of L-41 and HEp-2 cells with mumps virus was studied. By their morphology and rate of growth the chronically infected cultures (CIC) did not differ from the control cells. The CIC produced the infectious virus in titres of 2.5-6.5 lg ID50/ml. No virus could be detected after 48 passages in chronically infected L-41-MV cultures. Virus-specific antigen could be detected by fluorescent antibody technique in the cytoplasm of most CIC cells. In CIC L-41-MV massive hemadsorption was observed after the addition of guinea pig erythrocytes, in CIC HEp-2-MV no hemadsorption occurred. No temperature-sensitive mutants were formed when CIC were cultivated at 34 and 40 degrees C. CIC L-41-MV were shown to be resistant to reproduction of both hetero- and homologous viruses, CIC HEp-2-MV were resistant to mumps virus infection only.