Pathogen-binding Spectra of Two Homologous Serum Lectins with Different Monosaccharide Binding Specificities in the Common Carp Cyprinus carpio

Abstract

Lectins are key components of innate immunity, acting as pattern-recognition molecules and mediators of complement activation and pathogen elimination. In teleosts, two homologous collectins—a mannan-binding lectin (MBL) and a galactose-binding lectin (GalBL)—function in the lectin complement pathway. This study compared their binding specificities toward diverse microbes. Recombinant carbohydrate-recognition domains of MBL and GalBL were expressed and used to generate specific, non-cross-reactive antibodies. MBL exhibited a broader pathogen-binding spectrum, whereas GalBL showed distinct specificity. These results suggest complementary roles of the two collectins, contributing to functional diversification of innate immune responses in teleosts.