Intracellular distribution of rubella virus nonstructural protein P150

Antiserum prepared against an amino-terminal fragment of rubella virus (RUB ) nonstructural polyprotein was used to study RUB-infected Vero cells. Repl icase protein P150 was associated with vesicles and vacuoles of endolysosom al origin and later with large, convoluted, tubular membrane structures. Ne wly incorporated bromouridine was associated with the same structures and s pecifically with small membrane invaginations, spherules, indicating that t hese structures may he the sites of viral RNA synthesis.