[Identification of a myeloid differentiation factor 88 (MyD88) in Oncomelania hupensis against Schistosoma japonicum infection].

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 obtained 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 addition, 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 1 406 bp open reading frame (ORF), encoding 468 amino acid residues, which contained death domain and Toll/interlrukin-1 receptor (TIR) domain, the typical features 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.

CONCLUSIONS: MyD88-dependent signaling pathway is present in O. hupensis and plays an important role in innate immune response against S. japonicum infection.