The inhibitor-destroying activity of influenza A virus strains of differing neurovirulence for mice.

Abstract

Most strains of influenza A virus contain sialidases which are distinct from those of the host cell (Laver, 1963; Kelly & Grieff, 1965) and are presumed to be coded by the virus genome. However, the neurotropic variant nws, derived from the A0 strain ws (Stuart-Harris, 1939), did not elute readily after adsorption to red blood cells, or destroy the haemagglutination-inhibiting (HI) activity which various sialo-mucoids exhibit against sensitive test strains of influenza virus (Burnet & Lind, 1951). In contrast, the parent ws strain was active in both these tests. A decrease in viral sialidase activity may thus be a genetic marker or determinant of neurovirulence. On the other hand, these two viral characteristics could have arisen separately during the long series of chick embryo and animal passages by which nws was selected from ws, and have merely been accidentally associated in early allantoic fluid pools of this strain.