Association of polymorphic variant of exons 6 and 11 of lactoferrin gene with mastitis in Murrah buffalo

Lactoferrin is one of the important candidate genes for mastitis resistance in dairy animals. The gene is located on Bos taurus autosome (BTA) 22 and consists of 17 exons spanning over 34.5 kb of genomic DNA. The present study was undertaken to identify allelic variant in exons 6 and 11 of lactoferrin gene and to analyze association with incidence of clinical mastitis in Murrah buffalo. The amplification of exons 6 and 11 of lactoferrin gene yielded 301 and 131 bp amplicon size. Comparison of nucleotide sequence of exonic region of lactoferrin gene with Bos taurus (NCBI accession number AC_000179.1) revealed 6 mutations; among them 3 were in coding DNA sequence and remaining 3 were in flanking intronic region. All these mutations were found in exon 6 and synonymous in nature without affecting the sequence of amino acid. PCR-restriction fragment length polymorphism (RFLP) analysis of 301 bp amplicon using FokI restriction enzyme exhibited polymorphic pattern with two genotypes (AA and AB) with respective frequency of 0.625 and 0.375. The frequencies of two alleles, A and B were estimated as 0.81 and 0.19 respectively. RE Hpy188I and HinfI used for digestion of exon 11 had exhibited monomorphic pattern. The chi-square (χ2) analysis revealed significant association between incidence of clinical mastitis and genetic variant of exon 6 and animals with AA genotype were found to be less susceptible to mastitis. The findings indicate potential scope for incorporation of lactoferrin gene in selection and breeding of Murrah buffaloes for improved genetic resistance to mastitis.