[Inhibition of the reproduction of the influenza B virus by aprotinin].

Injection of aprotinin, a natural inhibitor of proteinases, into the allantoic cavity of chick embryos infected with influenza B/Lee/40 or B/HK/73 virus resulted in inhibition of proteolytic cleavage of virus hemagglutinin HA into HA1 and HA2, thereby decreasing the level of proteolytic activation of the synthesized virus particles. As a result of this inhibition in aprotinin-treated embryos, multicycle virus reproduction was limited and virus yields decreased considerably. The experimental results indicate the potential of chemotherapeutic inhibition of infection caused by influenza B viruses using antiproteinase agents interfering with proteolytic activation of virions.