Temperature-sensitive HVJ (sendai virus) with altered P polypeptide derived from persistently infected cell lines

HVJ isolated from culture fluids of G2, THEL and GM2 cells persistently infected with HVJ (G2-HVJ, THEL-HVJ and GM2-HVJ) were characterized in comparison with wild-type HVJ (HVJo). Viral structural proteins were analysed by 10% SDS-polyacrylamide gel electrophoresis and its was found that only the P polypeptides of all the HVJ clones isolated from G2-HVJ cells had a smaller size mol. wt. of 77 000 (77K), than that of HVJo with a mol. wt. of 79 000 (79K). One of six clones from THEL-HVJ cells and one of ten clones from GM2-HVJ cells exhibited the same migration pattern of P polypeptide as that of the clones from G2-HVJ cells. However, the other structural proteins were not different from those of the wild-type virions. All the clones from these carrier cultures were temperature-sensitive and were blocked in early step(s) required for RNA synthesis. These results indicate that some mutations(s) associated with P polypeptides could occur during the course of HVJ persistent infection in cell cultures.