Immune parameters in the humoral fluids of amphioxus Branchiostoma belcheri challenged with Vibrio alginolyticus

The knowledge concerning the humoral immunity is scarce in amphioxus Branchiostoma belcheri. This study measured the humoral parameters including lysozyme, antimicrobial activity, microbial agglutinin and haemagglutinin in amphioxus humoral fluids before and after Vibrio alginolyticus challenge. After challenged with V. alginolyticus, the lysozyme activity, growth inhibiting activities against Escherichia coli and V. alginolyticus and microbial agglutinating activities against Micrococcus lysodeikticus, Bacillus subtilis and Staphylococcus aureus were all increased significantly and haemagglutinating activities against rabbit and human A and O erythrocytes in the humoral fluids were all increased earlier. In contrast, the agglutinating activities against Vibrio harvey and E. coli in the humoral fluids were reduced in response to V. alginolyticus challenge and the haemagglutinating activity against human B erythrocytes increased later.