Chicken Ovotransferrin Variants OTF(B) and OTF(C) Harboring Substitution of GAT (Asp) to AAT (Asn) in the Codon 500 and their Antimicrobial Activity

Chicken egg white ovotransferrin (OTF) has been reported to exist in three electrophoretic variants (OTF(A), OTF(B) and OTF(C)). In this report, we identified a causal polymorphism between the OTF(B) and OTF(C) variants in Japanese and Taiwanese native chickens and compared the antibacterial activity between these two variants. The cDNA sequence analyses from Satsumadori oviducts revealed that three non-synonymous SNPs T1809G (Ser52Ala), A2258G (Ile96Val) and G7823A (Asp500Asn) corresponded to the OTF electrophoretic phenotypes. Of the three SNPs, the G7823A mutation perfectly corresponded to the electrophoretic phenotypes OTF(B) (G/G, Asp500Asp), OTF(B/C) (G/A, Asp500Asn) and OTF(C) (A/A, Asn500Asn) in three chicken populations. The variants OTF(B) and OTF(C) exhibited similar antibacterial potency against Gram-positive and Gram-negative bacteria. This study provides, for the first time, molecular information on polymorphism of OTF(B) and OTF(C) variants of chicken ovotransferrin and its effect on the antimicrobial activity of the respective variants.