Abstract Mannose-binding lectin (MBL) is a member ofthe collectin protein family that binds a broad range ofmicroorganisms and activates the lectin-complement pathwayof innate immunity. MBL deficiency is associated withan increased risk for various infections and arises from fivepolymorphisms in the promoter and first exon of the MBLgene in humans. In this study, three novel single-nucleotidepolymorphisms(SNPs) in the promoter regionandtwopreviouslyreportedSNPsinexon2oftheMBL1geneweredetectedusingPCRsinglestrandconformationpolymorphism,
restriction fragment length polymorphism, and DNAsequencing in 537 cattle from three Chinesebreeds.Analysisofthegenotypesandhaplotypes was used toinvestigate the polymorphisms and their possible implications,especially their association with serum MBL-Alevels, complement activity (CH50 and ACH50), and milkproduction traits was investigated. The g.2651G>A SNP inexon 2 affected the serum MBL-A concentrations and theserum CH50 values, whereas the g.−1330G>A SNPsignificantly affected CH50 and the somatic cell scores(SCSs). Statistical analysis revealed that cows with theATGGC/ACAAC combined genotype and those with theAAGGT/ACGGT combined genotype exhibited the lowestand highest SCSs, respectively. Serum antibacterial activitieswere also conducted to verify the effect of the SNPs onresistancetomastitispathogens. Results of real-time PCRshowed that the liver of cows with clinical mastitis exhibited ahigher MBL1 expression compared with healthy ones
(P<0.05). Findings of this study indicate that the MBL1gene possibly contributes to bacterial infection resistance andcan be used asamolecular marker of milk production traitsto control mastitis.
Keywords Mannose-binding lectin . Haplotype . MBL-Alevel . Complement activity. Bovine