TABLE 2.
Binding of mock-treated and NA-treated EM by avian and equine H3N8 influenza A virusesa
| Virus | Association constant (mU−1)
|
Relative affinity (KMT/KNA) | |
|---|---|---|---|
| KMT | KNA | ||
| Duck/Memphis/928/74 | 0.5 | 0.18 | 2.8 |
| Duck/Hokkaido/33/80 | 1.1 | 0.4 | 2.8 |
| Duck/Hokkaido/7/82 | 0.5 | 0.2 | 2.5 |
| Duck/Hokkaido/10/85 | 1.0 | 0.35 | 2.9 |
| Equine/Miami/63 | 0.45 | 0.01 | 45 |
| Equine/Algiers/72 | 0.5 | 0.02 | 25 |
| Equine/Fontainebleau/76 | 0.3 | 0.015 | 20 |
| Equine/Santiago/1/85 | 0.2 | 0.004 | 50 |
| Equine/Tennessee/5/86 | 0.2 | 0.012 | 17 |
| Equine/Kentucky/2/86 | 0.6 | 0.013 | 45 |
| Equine/Jilin/1/89b | 0.5 | 0.13 | 3.8 |
| Equine/Heilongjiang/15/90b | 0.8 | 0.07 | 11 |
a
Partially purified EM was treated with V. cholerae neuraminidase (NA) or mock treated (MT), and the binding of both preparations to the viruses was tested in a fetuin-binding inhibition assay as described in Materials and Methods. To calculate the constants, the concentration of the stock EM preparation was arbitrarily assigned a value of 1 U. The ratio KMT/KNA reflects a decrease in the affinity of the viruses for the EM after NA treatment.
b
Representatives of the H3N8 avian-like equine influenza virus lineage that emerged in China in 1989 (15).