Persistent SV5 virus infection in continuous cell cultures.

A continuous line of guinea pig kidney cells (CGPK/H) and a continuous line of mouse fibroblasts (L/H) spontaneously infected with parainfluenza virus SV5 were found. These cultures showed no enhanced cell degeneration or symplast formation, nor was haemagglutinin accumulation or infectious virus demonstrated in them. However, regular reproduction of ribonucleoprotein (RNP) characteristic of parainfluenza viruses, morphologically complete virions and antigens producing antibody to SV5 virus were found in the cells. Focal haemadsorption neutralized by antiserum to SV5 virus was also demonstrated. The infection persisted in the cell populations for over 2 years (the observation period) under standard conditions of cell dispersion and subcultivation.