Characterization of Schistosoma japonicum specific egg antigen recognized by circumoval precipitin (COP) producing monoclonal antibodies

Abstract

In order to analyze the antigens concerned with circumoval precipitin (COP) reactions, four monoclonal antibodies (18-4-1, 56-8-38, 85-16-1, 48-39-2) were obtained from spleen cells of mice infected with Schistosoma japonicum. All four gave positive COP reactions against S. japonicum eggs. All except 18-4-1, however, also reacted with S. mansoni eggs. Monoclonal antibodies 18-4-1 and 48-39-2 reacted specifically with schistosome egg antigens but not with antigens derived from adult schistosomes and 10 other species of helminths in enzyme-linked immunosorbent assay (ELISA), suggesting that these antibodies have high specificity and would be useful for characterization of the antigens concerned with COP reactions. The egg antigens recognized by antibodies 18-4-1 and 48-39-2 were identified by immunoblotting. Antibody 18-4-1 reacted only with S. japonicum egg antigens of mol. wt. 330 and 360 kDa, while 48-39-2 reacted with S. japonicum egg antigens of mol. wt. ranging from 58 to 265 kDa and with S. mansoni egg antigens of mol. wt. 62 kDa. The epitope recognized by 18-4-1 can be regarded as carbohydrate and peptide, whereas that recognized by 48-39-2 appears to be only carbohydrate. The COP antigens characterized by antibodies 18-4-1 and 48-39-2 have not been identified so far, on the grounds of differences in their specificity and molecular weight from those in previous reports.