关键词: 日本血吸虫, 重组抗原, 22.6kDa, 序列分析

Abstract: AIM: To sequence the cloned gene in pG Sj24 and to identify the encoded protein. METHODS: The cloned gene in pG Sj24 was digested from the recombinant plasmid by EcoRI,ligated into the M13mp19 vector and sequenced by automatic sequencer.The sequence was analyzed by Goldkey DNA and Protein Analytical Program and DNASIS Program.RESULTS: The pGSj24 cloned gene was demonstrated to be 840 bp containing one opened reading frame (ORF) with an initiation codon ATG at position 23 nt and a termination termination codon TAA at position 596 nt, encoding a protein with a molecular weight of 2216 kDa. At the upstream and down stream of the ORF there were termination codons, so the encoded protein was unable to be larger. However, there was a termination codon TAA at position 11 nt, suggesting why the 2216 kDa protein expressed separately. The nucleotide sequence of the pGSj24 cloned gene shared 95% identity with that of the corresponding part of S.japonicum 2216 kDa antigen gene, and 99.7% identity in the encoding part. The deduced amino acid scquence analysis showed a sequencemotif known as EF-Hand calcium binding domain, several endoplasmic reticulum targetting sequences and microbodies C-terminal targeting signals. The possible antigen determinants were predicted with in the amino acid fragments of 29-32aa, 63- 68aa and 87- 101aa. CONCLUSIONS: The cloned gene in pGSj24 is the gene that
encodes Sj22.6 kDa antigen.

Key words: Schistosoma japonicum, recombinant antigen, Sj 22.6, sequence analysis