MH-DAB gene polymorphism and disease resistance to Flavobacterium columnare in grass carp (Ctenopharyngodon idellus)

Abstract

In this study, the association between MH-DAB gene polymorphism and disease resistance was evaluated by challenging grass carp (Ctenopharyngodon idellus) with Flavobacterium columnare. Eight genotypes and six alleles were found, and named by common nomenclature. The genotypes AA, BB, EE, and DE, and the alleles Ctid-DAB1*0101, Ctid-DAB1*0201 and Ctid-DAB1*0401 were more preponderant in fish. The genotype BB was associated with higher resistance to F. columnare, as well as two alleles Ctid-DAB*0101 and Ctid-DAB*0201. Allele Ctid-DAB*0102 has decreased resistance to F. columnare. The expression of MH-DAB gene was decreased in the liver, kidney, and intestine but not in the spleen, gill, and skin at 2 days post infection (dpi), versus to that in the control group. MH-DAB gene expression was up-regulated in most tissues but remained at normal levels in the intestine at 15 days post infection. Our data suggested that MH-DAB polymorphism can be used as a potential genetic marker for disease resistance breeding of grass carp in the future.

Keywords: BLAST; Basic Local Alignment Search Tool; DNA; Disease resistance; Expression; Flavobacterium columnare; Grass carp (Ctenopharyngodon idellus); HLA-DR1; IHNV; LD(50); MH-DAB gene; MHC; PBR; PCR; PCR-SSCP; PCR-single-strand conformation polymorphism; Polymorphism; RNA; V; basic pair; bp; cDNA; cfu; colony-forming units; complementary deoxyribonucleic acid; d(N); d(S); days post infection; deoxyribonucleic acid; dpi; h; hour; human leukocyte antigen-DR1; infectious hematopoietic necrosis virus; lethal dose 50; major histocompatibility complex; min; minute; nonsynonymous substitution rate; peptide binding residue; polymerase chain reaction; ribonucleic acid; s; second; synonymous substitution rate; volta.