Expression of the Hemagglutinin Protein of Influenza Virus: Analysis of Protein Modifications

Baculovirus vectors have been developed for the expression of foreign genes in insect cells. Protein yields are often significantly higher than in bacterial, yeast, or vertebrate expression systems (12) . It was therefore of interest to test the capacity of this system to direct the complex and posttranslational modifications involved in the biosynthesis of most membrane and secretory proteins. To probe this question, the influenza virus hemagglutinin was expressed in Spodupteru frugiperdu (Sf9) cell cultures (3,4) and in larvae ofHeliothis virescens (5) .