The 22.6 kDa tegumental membrane-associated
antigen of schistosomes is of recognized importance in immunity to
schistosomiasis. In China, bovines are known to play an important role in the transmission of Schistosoma japonicum. Ten buffaloes (Bos buffelus) were vaccinated with a recombinant form (reSj-22) of the S. japonicum 22.6 kDa tegumental
antigen (Sj-22) and the sera were used to identify and map possible linear
B-cell epitopes on this molecule using a series of 18 overlapping synthetic
peptides (P1-P18). Sera from all of the ten vaccinated buffaloes reacted strongly with Sj-22 in western blots and in ELISA, while sera from a further ten adjuvant (
Quil A) control buffaloes did not. Four
peptides (P3, P8, P9 and P10) were predominantly recognized by at least 90% of the buffalo sera. This pattern of recognition is similar to that obtained in a previous study we undertook in mice immunized with the same
antigen whereby
peptides 3, 8, 9 and 10 were recognized by over 80% of CBA strain mice. The
peptide most frequently recognized by mice (
peptide 6), and mapping to an EF-hand
calcium binding domain, was recognized by six of the ten vaccinated buffaloes. The major difference between buffaloes and mice occurred with
peptide 1 which was recognized very frequently by all three strains of mice tested but was only weakly recognized by three of the ten buffaloes. This study provides a valuable reference for further study on the immunity stimulated by the 22.6 kDa tegumental
antigen in the murine model and a natural bovine host of
Schistosomiasis japonica.