Specificity of neuraminidase activity from influenza viruses isolated in different hosts tested with novel substrates

Influenza A and B viruses isolated in Vero and Madin Darby canine kidney (MDCK) cells as well as in fertilised hen eggs were tested for the specificity of their neuraminidase (NA) activity. Novel glycoconjugates with variations of terminally bound sialic acid mimicking the three main receptor types for influenza viruses were synthesised. These new substrates together with the lectin from Ricinus communis were used in a solid phase microtitre assay for the detection of NA specificity. Egg or MDCK isolated virus strains tended to exhibit highest NA activity against 3'sialyl-bound sialic acid whereas Vero isolated strains favoured 6'sialyl-(N-acetyllactosamine)-bound sialic acid. Differences were more pronounced for influenza A than for influenza B strains.