Abstract

Chemokines play a crucial role in the recruitment, activation and adhesion of immune effector cells to the foci of infection and injury under both homeostatic and inflammatory conditions. Identification of markers of chemokine genes associated with resistance to pathogens is necessary for the selective breeding of channel catfish. In the present study, the polymorphisms of genomic sequence of a CC chemokine, SCYA-115, were investigated in susceptible and resistant groups of channel catfish (Ictalurus punctatus). The polymorphisms in putative binding sites for transcription factor in promoter region were also investigated to explore their associations with susceptibility/resistance to Edwardsiella ictaluri. Thirty-five sites of SNPs and nine sites of ins-del polymorphisms were discovered in the complete sequence of SCYA-115. Among them, five SNP sites and one ins-del polymorphisms were found in the region of binding sites for the transcription factor. The allele and genotype distributions were examined at these six polymorphisms. The results indicate that -820 T allele, -752 ins allele and -752 ins/del genotype were more prevalent in resistant group than that in susceptible group, which suggested that the carriers of these polymorphisms are more resistant to E. ictaluri. In addition, significant differences were found in haplotypes between susceptible and resistant groups. The results provide candidate markers for the selection of channel catfish with enhanced resistance to E. ictaluri.

Keywords : Chemokine, polymorphism, channel catfish ictalurus punctatus, disease resistance, disease susceptibility