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Open Access Research article

Genome-wide association study for T lymphocyte subpopulations in swine

Xin Lu12, Wei-Xuan Fu13, Yan-Ru Luo1, Xiang-Dong Ding1, Jia-Peng Zhou1, Yang Liu1, Jian-Feng Liu1* and Qin Zhang1*

Author affiliations

1 Key Laboratory Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, College of Animal Science and Technology, National Engineering Laboratory for Animal Breeding, China Agricultural University, Beijing, 100193, China

2 State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, P.O. Box 5, Chang ping, Beijing, 102206, China

3 Department of Animal and Food Sciences, University of Delaware, Newark, DE, 19716, USA

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Citation and License

BMC Genomics 2012, 13:488  doi:10.1186/1471-2164-13-488

Published: 18 September 2012

Abstract

Background

Lymphocytes act as a major component of the adaptive immune system, taking very crucial responsibility for immunity. Differences in proportions of T-cell subpopulations in peripheral blood among individuals under same conditions provide evidence of genetic control on these traits, but little is known about the genetic mechanism of them, especially in swine. Identification of the genetic control on these variants may help the genetic improvement of immune capacity through selection.

Results

To identify genomic regions responsible for these immune traits in swine, a genome-wide association study was conducted. A total of 675 pigs of three breeds were involved in the study. At 21 days of age, all individuals were vaccinated with modified live classical swine fever vaccine. Blood samples were collected when the piglets were 20 and 35 days of age, respectively. Seven traits, including the proportions of CD4+, CD8+, CD4+CD8+, CD4+CD8−, CD4−CD8+, CD4−CD8− and the ratio of CD4+ to CD8+ T cells were measured at the two ages. All the samples were genotyped for 62,163 single nucleotide polymorphisms (SNP) using the Illumina porcineSNP60k BeadChip. 40833 SNPs were selected after quality control for association tests between SNPs and each immune trait considered based on a single-locus regression model. To tackle the issue of multiple testing in GWAS, 10,000 permutations were performed to determine the chromosome-wise and genome-wise significance levels of association tests. In total, 61 SNPs with chromosome-wise significance level and 3 SNPs with genome-wise significance level were identified. 27 significant SNPs were located within the immune-related QTL regions reported in previous studies. Furthermore, several significant SNPs fell into the regions harboring known immunity-related genes, 14 of them fell into the regions which harbor some known T cell-related genes.

Conclusions

Our study demonstrated that genome-wide association studies would be a feasible way for revealing the potential genetics variants affecting T-cell subpopulations. Results herein lay a preliminary foundation for further identifying the causal mutations underlying swine immune capacity in follow-up studies.

Keywords:
T lymphocyte subpopulations; Genome-wide association study; Swine