Molecular Cloning and Expression of FUT2-like Gene in the Oyster (Crassostrea gigas)

Abstract:

Norovirus (NoV) is the most common pathogen of acute viral gastroenteritis worldwide, which causes serious issues on public health and food safety. Histo-blood group antigens (HBGAs) have been recognized as receptors of NoV. It has been reported that type A-like HBGA presents in oyster gastrointestinal cells and induces specific accumulation of NoV in oysters. Alpha-1,2-fucosyltransferase (FUT2) is one of the key enzymes required in the HBGA synthesis. However, studies on FUT2 in oysters and other aquatic animals have been lacking. In this study, we cloned the FUT2-like gene in oysters (Crassostrea gigas) using homologous gene sequence method, and also analyzed the expression of FUT2-like gene in five tissues, including hepatopancrea, adductor muscle, mantle, labial palp and gills. The FUT2-like cDNA has a full length of 1941 bp, including a180-bp 5-untranslated region (UTR), a 1086-bp open reading frame (ORF) that encodes a protein of 361 amino acids, and a 675-bp 3-untranslated region (UTR). The molecular evolution analysis showed that the FUT2-like gene in oyster should be categorized into the same branch as FUT2 genes in Mus musculus and other mammals. The expression pattern of FUT2-like gene was analyzed in 5 tissues mentioned above. The results showed that the mRNAs of this gene were expressed in all 5 tissues; the expression level in labial palp was significantly lower than that in the other 4 tissues. Our results indicated that A-like HBGA in oyster might have a similar biosynthesis pathway as Type A HBGA in human. Our study should provide insights into the molecular mechanism of the accumulation of NoV in oysters.