Expression of five viral antigens in cells infected with wild-type and SSPE strains of measles virus: correlation with cytopathic effects and productivity of infections.

Cells infected with four strains (LEC, Biken, IP-3 and DR) of subacute sclerosing panencephalitis (SSPE) virus were compared with wild type measles virus (Edmonston) with respect to titers of extracellular virus, morphology of the cytopathic effect (CPE) and occurrence of different measles virus antigens within infected cells as determined by immune fluorescence. Murine monoclonal antibodies with specifities for the nucleocapsid (NP), polymerase (P), matrix (M), hemagglutinin (H), and fusion (F) proteins as well as specific hyperimmune sera prepared in rabbits against the NP, H and M proteins were used in immune fluorescence analyses of the various strains. All of the strains produced large amounts of NP and P. Only the NP antigen occurred in nuclei of cells. The Edmonston and LEC strains also showed bright fluorescence with the antibodies against the H, F, and M antigens. Immune fluorescent intensity was variably reduced in cells infected with the Biken, IP-3, and DR strains labelled with anti M, H, and F antibodies. The Biken strain produced moderate titers of extracellular virus and moderate amounts of M, H, and F antigens whereas the DR strain produced no extracellular virus and contained no detectable M or F and only trace amounts of H antigen. The IP-3 strain was intermediate both in antigen expression and in production of extracellular virus.