Removal of carbohydrate from influenza A virus and its hemagglutinin and the effect on biological activities.

Treatment of influenza virus and its purified hemagglutining with glycosidases from Diplococcus pneumoniae, which included beta-galactosidase, beta-N-acetylglucosminidase, and endoglycosidase D, released amino and neutral sugars from the virus and these as well as large oligosaccharides from the purified hemagglutinin. The released glucosamine-containing oligosaccharides were of one discrete size. Large oligosaccharides not removed by the glycosidases were found on the virus as well as the hemagglutinin. Some oligosaccharides on the virus were inaccessible to the enzymes, since they could be removed only from the purified hemagglutinin. Approximately 50% of the hemagglutinin carbohydrates could be removed without effect on hemagglutinating activity. Similarly, removal of 20 to 25% of the carbohydrates from intact virus particles did not alter infectivity.