Characterisation of a natural haemagglutinin with affinity for acetylated aminosugars in the serum of the marine prawn,Penaeus indicus(H. Milne Edwards)

A natural haemagglutinin was detected in the serum of the marine prawnPenaeus indicus, using mammalian erythrocytes (RBC). The haemagglutination profile and cross-adsorption tests revealed a strong reactivity with human A RBC, and trypsinisation of this RBC type enhanced their susceptibility for agglutination by the serum. The agglutinating activity did not require Ca2+2+deg;C. Ammonium sulphate and trichloroacetic acid completely precipitated the haemagglutinating activity from serum, suggesting it is a protein or glycoprotein. However, neither trypsin treatment nor periodate oxidation of serum abrogated the agglutinating activity. Haemagglutination-inhibition assays performed with several carbohydrates and glycoproteins revealed a unique specificity of serum agglutinin for acetylated aminosugars and that the presence of the acetyl group was essential for agglutinin-ligand interaction. The haemagglutinating activity of the serum could be specifically inhibited by lipopolysaccharide fromSalmonella abortus equi, but not with lipopolysaccharide from five other bacterial species.