An Improved Procedure for Measuring Neuraminidase Antibodies by Hemagglutination-Inhibition

Abstract

Neuraminidase antibodies are known to inhibit hemagglutination by X-15 and X-15 (HK) recombinant viruses. However, the level of inhibition observed varies when different batches of chicken erythrocytes are employed, and the test generally detects neuraminidase antibodies with less sensitivity than an enzyme inhibition test. By titrating neuraminidase antibodies in the presence of anti-IgG globulins, with appropriate specificity, the hemagglutination-inhibition activity of neuraminidase antibodies is enhanced and the effect of cell variation is minimized. Consequently results obtained with this modified method for titrating neuraminidase antibodies become comparable to those obtained by measuring enzyme-inhibition. The improved hemagglutination-inhibition procedure possesses the important advantages of greater convenience and economy. Similar enhancing effects may also be obtained with egg white and guinea pig serum.