[Variations in the NP protein of the influenza virus detected by peptide mapping and polyacrylamide gel electrophoresis].

NP proteins of 19 reference and 42 epidemic strains of influenza A virus were analysed for their mobility in polyacrylamide gel electrophoresis and distribution of tryptic peptides. The strains could be divided into 4 groups by differences in their electrophoretic mobility, and into 9 groups according to reproducible differences of several hydrophilic peptides determined by peptide mapping.