THE MUMPS-VIRUS V-PROTEIN IS UNSTABLE IN VIRUS-INFECTED CELLS

The mumps virus (MuV) V protein was characterized in virus infected ce lls by the use of antipeptide sera. In radioimmune precipitation assay (RIPA), the sera reacted with the V protein and also immunoprecipitat ed the nucleocapsid (NP) and phospho (P) proteins. However, by depleti on RIPA (in which either the NP and P proteins or the V protein were r emoved) and Western immunoblotting, it was demonstrated that the V pro tein was not associated with the NP and P proteins, but that the anti- V sera cross-reacted with the NP protein. Pulse-chase experiments demo nstrated that the V protein was gradually decreased during the chase p eriod and could not be detected by antibodies raised against peptides representing three different regions of the protein at the end of the chase, while the NP and P proteins were relatively stable during the c hase period. These results suggest that the V protein is unstable and degraded gradually in virus infected cells.