Electrophoretic separation and characterization of subunits released from influenza virus by detergents

Subunits released from influenza A/Singapore/1/57 (H2N2) virus by either Triton-X-100 (T-X-100); or sodium lauryl sarcosinate (SLS) or ether were separated by electrophoresis in agarose suspension into a rapidly migrating fraction (I) and a slowly migrating fraction (II). Fraction I obtained after T-X-100 treatment contained the viral ribonucleoprotein (RNP) in a form indistinguishable from the obtained after ether treatment. SLS treatment of the virus resulted in a rapidly migrating fraction containing only the protein part of the viral RNP. Fraction II obtained after T-X-100 or SLS treatment contained both haemagglutinin (HA) and neuraminidase (NA), mostly dissociated from each other, in contrast to fraction II obtained after ether treatment which contained mixed aggregates of HA and NA. The yields of electrophoretically isolated RNP and HA-NA were essentially the same irrespective of whether T-X-100 or ether was used for virus disruption. Treatment of virus by T-X-100 and subsequent removal of the latter resulted in a 10-20-fold increase of the HA activity. After sodium dodecyl sulphate (SDS) treatment of the virus, the NA activity was found in a heterogeneous fraction with surprisingly high migration rate towards the anode, indicating that NA remained active despite its extensive SDS binding.