Superinfection of HVJ Carrier HeLa Cells with Ultraviolet-Irradiated Newcastle Disease Virus

Abstract

The mechanism of enhancement of growth of partially ultraviolet (UV)-inactivated Newcastle disease virus (NDV) in HeLa cells persistently infected with hemagglutinating virus of Japan (HVJ) (HeLaHVJ) was investigated. HelaHVJ cells and normal HeLa cells were inoculated with UV-irradiated NDV under similar experimental conditions, and numbers of both infective centers and NDV-antigen producing cells in each culture were counted. It was found that the percen-tage of HeLaHVJ cells which produced infectious NDV or NDV-antigen during the first cycle of infection was approximately 1.5 times higher than that of normal HeLa cells. Survival rurvs of UV-irradiated NDV showed that NDV appeared more resistant to UV when titrated in HeLaHVJ cells than in assay in normal HeLa cells. Possible explanations for this phenomenon were discussed