RED-CELLS BOUND TO INFLUENZA-VIRUS N9 NEURAMINIDASE ARE NOT RELEASED BY THE N9 NEURAMINIDASE ACTIVITY

Influenza virus neuraminidase (NA) of the N9 subtype also possesses he magglutinin activity and the hemagglutinating, or hemabsorbing (HB), s ite is distinct from the catalytic site. Previous results suggested th at the NA was binding to sialic acid on the red cell surface, but we n ow report that the HB receptor is nor sensitive to N9 influenza neuram inidase activity. Cell lines that constitutively express N9 or N2 neur aminidase have been used to further investigate the specificity of red blood cell binding to the HB site. The results suggest that the ligan d is N-acetylneuraminic acid in a linkage or environment that is not s ensitive to influenza virus neuraminidase, but which is released by th e broadly specific bacterial sialidases from Micromonospora viridifaci ens or Arthrobacter ureafaciens. (C) 1995 Academic Press, Inc.