Comparison of L proteins of vaccine and wild-type measles viruses

The nucleotide sequences of the large (L) genes of ten measles virus (MV) s trains were determined. These strains included the Moraten and Rubeovax vac cine strains and their Edmonston wild-type (wt) progenitor, two additional vaccine strains and five genotypically divergent wt isolates. The nucleotid e and predicted amino acid sequences were compared with six previously sequ enced L genes and the number and location of variable amino acid positions were characterized. The recent wt isolates demonstrated the greatest amount of variability found to date in the highly conserved L protein. Three full -length wt L proteins were expressed in mammalian cells and their ability t o form a complex with the MV phosphoprotein was demonstrated. While no set of amino acid substitutions associated consistently with wt or vaccine stra ins was identified, these data will provide a basis for the analysis of the activity of L proteins from vaccine and wt viruses in a functional assay.