Abundant β-Defensin Copy Number Variations in Pigs

TL;DR

This study found that pigs have significant variations in the number of β-defensin genes, which could help improve their resistance to infections.

Contribution

A new quantitative PCR method was developed to measure β-defensin copy number variations in pigs.

Findings

CNVs in 13 pBD genes ranged from two to five copies across different pig breeds.

Berkshire pigs had higher mean copy numbers of pBDs compared to Landrace pigs.

Genomic copy number strongly correlated with gene expression levels in the kidney for certain pBDs.

Abstract

Background/Objectives: β-defensins are a family of classical endogenous antimicrobial peptides involved in innate immune response. β-defensins are encoded by a large number of loci and known to show extensive copy number variations (CNVs) that may be useful as DNA markers for host resilience against pathogenic infections. Methods: We developed a quantitative PCR-based method to estimate the genomic copy numbers of 13 pig β-defensin (pBD) genes and analyzed the range and extent of CNVs across several commercial pig breeds. Results: We assessed 38 animals from four pure breeds and a crossbreed and observed CNVs ranging from two to five genomic copies from pBD114, pBD115, pBD119, pBD124, pBD128, and pBD129, indicating extensive individual variations of gene copy numbers of these genes within each breed. The mean copy numbers of these pBDs were lower in Landrace and higher in Berkshire than in other breeds. We also observed a strong correlation between the genomic copy number and their expression levels with the correlation coefficient (r) > 0.9 for pBD114, pBD119, and pBD129 in the kidney, with these genes being highly expressed. Conclusions: Although we only analyzed 13 pBDs among 29 reported genes, our results showed the presence of extensive CNVs in β-defensins from pigs. The genomic copy number of β-defensins may contribute to improving animal resilience against pathogenic infections and other associated phenotypes.

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