Biological hemagglutination activity

The biological activity of acid mucopolysaccharides is discussed in Section 9. They are instrumental in hemagglutination inhibition of viruses, in enhancing virulence of bacteria (S25-S27), and in antilipemic (Cl, C2, P4) and lipotropic activity (C4). They were also reported to have strong antipeptic activity (K21, K24) which we (unpublished) found, however, to be rather low. 

In our original papers (22,23,25) we used lactoperoxidase-catalyzed radio-iodination. If you prefer to use another method of iodination then we strongly recommend comparing the biological activity, before and after the radio-iodination of the F(ab )2 fragments, by hemagglutination (39). 

Some surface assays are based on whole cells and thus have the benefit that they can measure biological activity on biological surfaces. Hemagglutination assays involve observation of the agglutination of erythrocytes by bacteria, viruses. 

Sialic acid was the first virus receptor identified. Hirst and McClelland and Hare discovered that influenza virus is able to hemagglutinate and that adsorbed virus is eluted from erythrocytes on incubation at 37°C, indicating an enzymatic destruction of a receptor substance on the cells [1, 2]. When a similar enzymatic activity was subsequently detected in Vibrio cholerae cultures, the term receptor-destroying enzyme was introduced [3]. The substance released by the viral enzyme from soluble hemagglutination inhibitors was initially characterized as a carbohydrate of low molecular weight [4] and then identified in crystalline form as A-acetyl-o-neuraminic acid [5]. Thus, it was clear that the receptor determinant of influenza virus was sialic acid and that the viral enzyme was a neuraminidase. Furthermore, for the first time an important biological function of sialic acid had been identified. 

Pepper (1968) investigated the role of sialic acid in horse serum on the inhibition of hemagglutination by Asian influenza virus. Horse serum has N-acetyl, N-glycoyl, and the 4-0-acetylated derivatives of neuraminic acid (cf. Chapter 1). The biological activity of horse serum specifically toward the Az strain of influenza virus appears to be determined by the N,0-diacetylneuraminic acid component in c -ma-croglobulin. 

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