EVIDENCE FOR ANTIGENIC VARIATION IN INFLUENZA-A NUCLEOPROTEIN

Nucleoprotein (NP) antigens isolated from sodium sarcosyl detergent-disrupted influenza A virus particles by cellulose acetate electrophoresis were used to prepare specific immune sera. Antigenic analysis of the nucleoproteins by immuno-double-diffusion and antibody absorption tests revealed antigenic differences in the nucleoprotein antigens of human A/PR8/34 (HON1) virus and viruses of the Hong Kong (H3N2) subtype. The nucleoprotein antigens of avian A/duck/Ukraine/1/63 (Hav7Neg2) and A/swine/Iowa/15/30 (Hsw1Nl) viruses resembled more closely the NP of A/PR8/34 virus than the NP of human H3N2 strains. Antigenic analysis of recombinant strains prepared from A/PR8/34 and H3N2 parent viruses indicated that the parental origin of the NP antigens could be clearly identified. Identification of the nucleoproteins of parental and recombinant influenza A viruses by migration rate analysis of NP polypeptides and RNA genes by electrophoresis on polyacrylamide gels gave results which correlated with the antigenic characterization of their NP antigens. The findings suggested that antigenic drift" occurs in the nucleoproteins of human influenza A viruses. © 1979."