Single Nucleotide Polymorphism in the Promoter Region of BovineInterleukin 8 Gene and its Association with Milk Production Traits andSomatic Cell Score of Holstein Cattle in Iran

Abstract

Background: Interlekin 8 (IL8) is a proinflammatory cytokine and a potent chemotactic and activation factor for neutrophils. It has been reported to be expressed at high levels by various cell types after immune stimulation and mediates neutrophil recruitment in host. Objectives: The aim of this study was to analyze the relationship between single nucleotide polymorphisms (SNPs) at position -180 G/A in the promoter region of bovine IL8 gene with milk production traits and somatic cell score (SCS). Materials and Methods: The part of promoter region in the bovine IL8 gene containing -180 G/A SNP was screened by a single strand conformation polymorphism (SSCP) and DNA sequencing in Holstein cattle of Iran. The association analysis between different genotypes of IL8-180 SNP and performance traits of Holstein cattle was carried out by Mixed procedure of SAS 9.1 program. Results: A total of 3 distinct SSCP patterns were observed. Sequence analysis indicated a reported polymorphism at position -180 G/A relative to the start codon. This SNP created a putative binding site for Oct-1 transcription factor which associated with lower SCS. The association of IL8-180 genotypes was studied with milk production traits and SCS. The IL8180 associated (P<0.05) with milk yield and also tended to associate with SCS (P=0.06), but their association with milk fat percentage and milk protein percentage were not significant. Conclusion: The SNP at position -180 in the promoter region of bovine IL8 gene was found to be associated with milk yield in Holstein cattle. Gene expression analysis and genome wide association studies were required to confirm the functional role of the IL8-180 SNP.