A new L-type lectin (LvLTLC1) from the shrimp Litopenaeus vannamei facilitates the clearance of Vibrio harveyi

According to structures and functions of lectins found in shrimp, they are classified into seven types, namely, L-type, C-type, P-type, M-type, galectins, fibrinogen-like domain lectins, and calnexin/calreticulin. Until now, the researches of shrimp lectins are mainly focused on C-type lectins. In this study, we identified a new L-type lectin, designated as LvLTLC1, from the shrimp Litopenaeus vannamei. The cDNA of LvLTLC1 is 1184 bp with an open reading frame of 990 bp encoding a protein of 329 amino acids. The LvLTLC1 protein contained a putative signal peptide, an L-type lectin-like domain, and a transmembrane helix region. Phylogenetic analysis showed that LvLTLC1 belonged to VIP36-like family. LvLTLC1 was expressed in all examined tissues but had higher expression level in gills and hepatopancreas than other tissues. LvLTLC1 expression was up-regulated after immune challenge by Vibrio harveyi and lipopolysaccharide. The recombinant LvLTLC1 agglutinated Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (V. harveyi, V. parahaemolyticus, V. alginolyticus, V. cholerae, V. vulnificus, Pseudomonas aeruginosa, P. fluorescens) in a calcium-independent manner. Recombinant LvLTLC1 exerted the ability of enhancing the clearance of V. harveyi injected in shrimp. Our results indicated that LvLTLC1 functions in anti-pathogen innate immunity of shrimp.