REVERSAL OF THE MEASLES VIRUS-MEDIATED INCREASE OF PHOSPHORYLATING ACTIVITY IN PERSISTENTLY INFECTED-MOUSE NEUROBLASTOMA-CELLS BY ANTI-MEASLES VIRUS-ANTIBODIES

To investigate the effect of persistent measles virus infection on sig nal transduction in cells of neuronal origin, the mouse neuroblastoma cell line NS20Y/MS, which is persistently infected with measles virus, was used. The results demonstrate an approximate 50% increase in tota l phosphorylation and a similar increase in protein kinase C (PKC) act ivity. Western blot analysis with anti-total PKC or anti-PKC-alpha ant ibodies revealed a significant increase in the level of an 80K immunor eactive PKC in NS20Y/MS cells. Following incubation of NS20Y/MS cells with polyclonal anti-measles virus antibodies, which down-regulate the level of measles virus proteins, total and PKC-mediated phosphorylati on returned to the basal level of uninfected cells. This effect was re versible and removal of the antibodies resulted in restoration of the high level of total and PKC-mediated phosphorylation. The release of i nfectious measles virus was strongly inhibited by incubation of NS20Y/ MS cells with the PKC inhibitor, 1-(5-isoquinolinylsulphonyl)-2-methyl piperazine (H-7). These results demonstrate that measles virus induces elevation in cellular phosphorylation which is essential for measles virus production.