Sequence analysis of En gam22 . (A) RT-PCR product of Engam22. Total RNA was extracted from purified gametocytes at 168 h PI, target gene was amplified using specific primer En1 (Table 1). Lane 1 was DNA marker, lane 2 and 3 were products of Engam22. (B) Predicted protein sequence of Engam22. The signal peptide and histidine-proline rich region was marked by box, and the splice site was between 19 and 20 amino acid. (C) Comparison of GAM22 proteins from E. tenella and E. necatrix. Invariable amino acid positions are marked with asterisks, and substitutions rated conservative and semiconservative by ClustalW are marked with colons and periods, respectively.