ABSTRACT
Objective To identify a myeloid differentiation factor 88(MyD88)in Oncomelania hupensis,and characterize the role of MyD88 against Schistosoma japonicum infection. Methods The complete cDNA of MyD88 in O. hupensis was ob-tained by using rapid amplification of cDNA ends(RACE),and homologues sequences and conserved domains were aligned and the structure of MyD88 was predicted either. A phylogenetic tree of MyD88 was further constructed with other species. In ad-dition,the mRNA expression level of O. hupensis MyD88 before and after S. japonicum infection was investigated by real-time quantitative PCR(RT-qPCR). Results The cDNA of O. hupensis MyD88 consisted of 1406 bp open reading frame(ORF),en-coding 468 amino acid residues,which contained death domain and Toll/interlrukin-1 receptor(TIR)domain,the typical fea-tures of MyD88 family proteins. The predicted amino acid sequence of O. hupensis MyD88 shared 38%-52%identity with other mollusc. O. hupensis MyD88 was phylogenetically closeted to Biomphalaria glabrata MyD88. The O. hupensis MyD88 existed in all selected tissues and expressed highly in hemocyte,up-regulated after S. japonicum infection in all selected tissues except cephalopodium,especially higher in whole snail and hemocyte. Conclusion MyD88-dependent signaling pathway is present in O. hupensis and plays an important role in innate immune response against S. japonicum infection.