Antiviral Activity of Antiserum Specific for an Influenza Virus Neuraminidase

Abstract

Antiserum specific for influenza A 2 neuraminidase was produced by immunization of rabbits with the purified enzyme which had been isolated by electrophoresis from the proteins of a detergent-disrupted A 0 A 2 influenza virus recombinant [X-7 (F1)]. This recombinant contained hemagglutinin of the A 0 subtype and A 2 neuraminidase. Antiserum to the isolated A 2 neuraminidase did not react in any of four serological tests with A 0 or A 2 subtype viruses that lacked the A 2 enzyme. In contrast, the antiserum inhibited the neuraminidase activity only of wild-type and recombinant viruses containing the A 2 enzyme, regardless of the nature of their hemagglutinin proteins. The antiserum caused hemagglutination-inhibition of some, but not all, viruses bearing the A 2 enzyme, and it reduced the plaque size or plaque number of all viruses tested that contained A 2 neuraminidase. In the chick embryo and in cell culture, low dilutions of antiserum reduced the yield of virus. True neutralization of virus in the chick embryo did not occur. We conclude that an antiserum specific for A 2 neuraminidase influenced the yield and release of virus from influenza virus-infected cells.