Detection of nucleotide variants in FCGRT (Fc fragment of IgG, receptor, transporter, alpha) gene and their influence on colostral IgG concentration in Indian water buffalo (Bubalus bubalis).

Abstract

The neonatal Fc receptors (FcRn) mediate the transfer of immunoglobulin G (IgG) molecules from a dam's circulation to the colostrum produced by it immediately after parturition. In ruminants, the calves born are agammaglobulinemic therefore, ingestion of colostrum with high concentration of IgG imparts passive immunity to the newborn. The FcRn molecule is a heterodimer, coded by FCGRT (Fc fragment of IgG Receptor Transporter neonatal) and B2M (Beta 2 microglobulin) genes. Present study attempted to identify single nucleotide polymorphisms (SNPs) in the FCGRT gene in 40 buffaloes of Murrah breed and evaluated the association of these nucleotide variations and haplotypes with IgG concentration in their colostrum. Animals producing colostrum with high IgG and low IgG levels were identified by indirect ELISA and selected. SNPs were detected in the FCGRT gene sequence of selected animals by amplifying it in nine fragments covering all exons (with flanking introns) followed by PCR-single strand conformational polymorphism (PCR-SSCP). A total of nine SNPs were observed of which seven were present in flanking introns and two in exon 4 of the gene. The SNP A75G was non-synonymous and produced an amino acid change from isoleucine to valine. The exonic SNPs and corresponding haplotypes were found to be significantly (P < 0.01 and 0.05 respectively) associated with colostral IgG concentration based on Odds ratios at 95% confidence interval. Polymorphism in FCGRT gene is found to be associated with IgG concentration in colostrum and identification of females with desirable variations may prevent failure of passive transfer in neonatal ruminants.