A comparison of the structural polypeptides of five strains of mumps virus.

The polypeptide patterns of five strains of mumps virus have been compared under uniform electrophoresis conditions. These strains included the MJ and RW strains, recently isolated from human cerebrospinal fluid, the neuro-adapted Kilham strain and the chick embryo-adapted Enders and Jeryl Lynn strains. A similar pattern of polypeptides, featuring six common and virus-specific species, was obtained with purified virus grown in ovo, in hick embryo fibroblasts (CEF) or in Vero cells. These polypeptides have been designated VP1 (mol. wt. 200000), VP2 (mol. wt. 80000 or 75000), VP3 (mol. wt. 68000), VP4 (mol. wt. 58000), VP5 (mol. wt. 45000), VP6 (mol. wt. 39000). The virus glycoproteins were identified as VP2 and VP4; the nucleocapsid-associated proteins as VP1, VP3 and VP5. Additional polypeptides occurring both in uninfected Vero cells and in uninfected CEFs appeared in polypeptide profiles of purified mumps virus preparations, and could not be designated virus-specific polypeptides. Alhtough strain differences were minimal, we did observe (1) an extra protein, nucleocapsidassociated, in patterns from the chick-adapted Enders strain of mumps virus and (2) strain-dependent variability in the size of VP2.