INTERFERON SUSCEPTIBILITY OF VARIOUS CELL-LINES PERSISTENTLY INFECTED WITH HEMAGGLUTINATING VIRUS OF JAPAN (HVJ)

Various cell lines persistently infected with para-influenza I virus, HVJ strain, were less susceptible to the antiviral action of interferon than the same cell lines when not infected with HVJ. When Vero cells persistently infected with a temperature-sensitive strain of HVJ were incubated at 38°C, a non-permissive temperature, they became fully susceptible to interferon whereas neither the haemadsorbing nor the cell-associated haemagglutinating activity of the virus was expressed. These findings suggest that the lowered interferon susceptibility of virus-carrier cells may be related to the maturation of virus in them. It was found that the low susceptibility of virus-carrier cells to interferon is not due to blocked adsorption of interferon or to inability of the cells to respond to interferon. Studies with actinomycin D suggest that some step (or steps) before the synthesis of the messenger RNA for the antiviral protein is blocked.