Effect of serum from tilapia Oreochromis aureus immunized with the dinospore Amyloodinium ocellatum on the motility infectivity and growth of the parasite in cell culture

Abstract

Serum from the tilapine fish Oreochromis aureus immunized intraperitoneally with Amyloodinium ocellatum dinospores stimulated an immune response that was detectable by enzyme-linked immunosorbeut assay (ELISA), cell culture infectivity, and motility assays. A response was detected as early as 3 wk in both the ELISA and infectivity assay with immune serum inhibiting the infectivity and growth of the parasite in cell culture. Parasite infectivity in cell culture was inversely related to serum antibody ELISA titers, Fresh serum had a greater inhibitory effect than heat-inactivated serum. Live parasites induced a greater immune response than did dead, sonicated parasites as determined by both the ELISA and the infectivity assay. Serum from fish immunized with live parasites immobilized the infective dinospores at serum concentrations of 5 % and greater by 5 min, as well as in lower serum concentrations at longer time intervals. Parasite agglutination occurred in immune serum concentrations from 2.5 to 0.156 %.