Measles Virus-Specified Polypeptide Synthesis in Two Persistently Infected HeLa Cell Lines

Abstract

Measles virus-directed protein synthesis was examined in 2 HeLa [human cervical carcinoma] cell lines (K11 and K11A) that are persistently infected with wild-type measles virus. Four viral proteins (H [hemagglutination protein], P [nucleocapsid-associated protein], NP [the major nucleocapsid protein] and M [the matrix protein]) were readily detected in both cell lines by immune precipitation of [35S]methionine-labeled cell extracts followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis [SDS-PAGE]. When analyzed by SDS-PAGE, 3 (H, NP and M) of the 4 viral proteins in K11 and K11A cells differed from the corresponding viral proteins synthesized in HeLa cells acutely infected with the parental wild-type virus. The M protein from K11A cells migrated significantly more slowly on SDS-PAGE than the M protein from K11 cells and there appeared to be slight differences in the H and NP proteins between these 2 persistently infected cell lines. The altered viral proteins detected in K11 and K11A cells appeared to be the result of viral mutations rather than changes in the host cell, since virus recovered from these cells directed the synthesis of similar aberrant viral proteins in HeLa cells. Viruses recovered from K11 and K11A cells were temperature-sensitive and grew more slowly than wild-type virus. HeLa cells infected with virus recovered from K11 cells readily became persistently infected, resembling the original persistently infected K11 cells. Viral mutations are associated with persistent measles virus infections in cell cultures.