Molecular characterization and functional analysis of Collectin-11 from Hexagrammos otakii.

Hexagrammos otakii is an essential economic fish for some coastal cities, but severe and frequent infections have appeared in aquaculture. Previous studies have shown that collectin-11 (CL-11) is a typical soluble pattern recognition receptor capable of recognizing pathogens and initiating the complement cascade by interacting with mannan-binding lectin-associated serine protease-1 (MASP1). Hence, to better understand the functions of CL-11 in Hexagrammos otakii (HoCL-11), we conducted qRT-PCR, LPS and PGN binding, bacterial agglutination, ELISA, and FAR-WESTERN after recombinant expression. As a result, qRT-PCR revealed that the HoCL-11 gene was predominantly expressed in the liver, skin, and ovary tissues of Hexagrammos otakii. Bacterial agglutination and binding assays showed that the recombinant CL-11 protein could recognize various pathogens. ELISA and far-western experiments confirmed that HoCL-11 could bind to MASP1 and MASP2 and may further activate the complement. In conclusion, HoCL-11 is pivotal in teleost Hexagrammos otakii's immune defense, and this study has theoretically supplemented its innate immune mechanism.