Characterization of the Ribonucleoprotein and Neuraminidase of Influenza A Viruses by Immunodiffusion

Summary Immunodiffusion and immunoelectrophoretic studies were made with rabbit antisera and purified influenza A viruses disrupted by sodium dodecyl sulphate. These techniques permitted the characterization of the type-specific ribonucleoprotein antigen and influenza A2 neuraminidase. A common precipitin line was obtained with different human and avian influenza A viruses when an antiserum for the ribonucleoprotein antigen of influenza A was used. A rabbit antiserum against purified influenza A2 neuraminidase gave identical precipitin lines with different influenza A2 viruses and with two recombinant strains known to contain influenza A2 neuraminidase, but not with influenza A0, A1 or fowl plague virus. No precipitin line corresponding to haemagglutinin could be detected with influenza A2 viruses treated with sodium dodecyl sulphate. In a comparison of the effects of other virus disrupting agents on the detection of influenza virus antigens by immunodiffusion, only ‘Nonidet P40’ gave results as satisfactory as those obtained with sodium dodecyl sulphate in the characterization of the ribonucleoprotein and neuraminidase antigens.