A study of measles virus antigens in acutely and persistently infected cells using monoclonal antibodies: differences in the accumulation of certain viral proteins.

Monoclonal antibodies were used to study measles virus (Hallé strain) infections. The distribution of virus antigens in acutely and persistently infected cells was examined by immunofluorescence, and the synthesis of the virus polypeptides in acutely infected cells was measured after immunoprecipitation and analysis in SDS-polyacrylamide gels. The virus nucleoprotein (NP) was detected 12 h after infection and was the major virus polypeptide synthesized throughout the virus cycle. The NP, matrix, and polymerase (L) polypeptides were first detected associated with the perinuclear membrane, but were later distributed throughout the cytoplasm. The hemagglutinin accumulated in the cell membrane in well-defined 'clusters'. In comparison with the acutely infected system, persistently infected cells presented important differences. There were only low levels of L polypeptides, and up to 50% of the cells contained intranuclear inclusions which stained specifically with NP monoclonal antibody. The relevance of these observations is discussed.