Department of Animal Science, Iowa State University, Ames, IA, USA.
Department of Agronomy, Iowa State University, Ames, IA, USA.
BMC Genomics. 2020 Sep 22;21(1):648. doi: 10.1186/s12864-020-06994-0.
Disease resilience is the ability to maintain performance under pathogen exposure but is difficult to select for because breeding populations are raised under high health. Selection for resilience requires a trait that is heritable, easy to measure on healthy animals, and genetically correlated with resilience. Natural antibodies (NAb) are important parts of the innate immune system and are found to be heritable and associated with disease susceptibility in dairy cattle and poultry. Our objective was to investigate NAb and total IgG in blood of healthy, young pigs as potential indicator traits for disease resilience.
Data were from Yorkshire x Landrace pigs, with IgG and IgM NAb (four antigens) and total IgG measured by ELISA in blood plasma collected ~ 1 week after weaning, prior to their exposure to a natural polymicrobial challenge. Heritability estimates were lower for IgG NAb (0.12 to 0.24, + 0.05) and for total IgG (0.19 + 0.05) than for IgM NAb (0.33 to 0.53, + 0.07) but maternal effects were larger for IgG NAb (0.41 to 0.52, + 0.03) and for total IgG (0.19 + 0.05) than for IgM NAb (0.00 to 0.10, + 0.04). Phenotypically, IgM NAb titers were moderately correlated with each other (average 0.60), as were IgG NAb titers (average 0.42), but correlations between IgM and IgG NAb titers were weak (average 0.09). Phenotypic correlations of total IgG were moderate with NAb IgG (average 0.46) but weak with NAb IgM (average 0.01). Estimates of genetic correlations among NAb showed similar patterns but with small SE, with estimates averaging 0.76 among IgG NAb, 0.63 among IgM NAb, 0.17 between IgG and IgM NAb, 0.64 between total IgG and IgG NAb, and 0.13 between total IgG and IgM NAb. Phenotypically, pigs that survived had slightly higher levels of NAb and total IgG than pigs that died. Genetically, higher levels of NAb tended to be associated with greater disease resilience based on lower mortality and fewer parenteral antibiotic treatments. Genome-wide association analyses for NAb titers identified several genomic regions, with several candidate genes for immune response.
Levels of NAb in blood of healthy young piglets are heritable and potential genetic indicators of resilience to polymicrobial disease.
疾病弹性是指在病原体暴露下维持性能的能力，但由于繁殖群体在高健康水平下饲养，因此难以选择。对弹性的选择需要一个可遗传的、在健康动物身上易于测量的、与弹性遗传相关的特征。天然抗体（NAb）是先天免疫系统的重要组成部分，已被发现具有遗传性，并与奶牛和家禽的疾病易感性相关。我们的目标是研究健康仔猪血液中的 NAb 和总 IgG，作为疾病弹性的潜在指标特征。
数据来自约克夏 x 长白猪，通过 ELISA 法测量了 IgG 和 IgM NAb（四种抗原）以及总 IgG，在断奶后约 1 周、接触天然多微生物挑战之前采集了血浆样本。IgG NAb（0.12 至 0.24，+0.05）和总 IgG（0.19 + 0.05）的遗传力估计值低于 IgM NAb（0.33 至 0.53，+0.07），但 IgG NAb（0.41 至 0.52，+0.03）和总 IgG（0.19 + 0.05）的母体效应大于 IgM NAb（0.00 至 0.10，+0.04）。表型上，IgM NAb 滴度相互中度相关（平均 0.60），IgG NAb 滴度也中度相关（平均 0.42），但 IgM 和 IgG NAb 滴度之间的相关性较弱（平均 0.09）。总 IgG 与 NAb IgG 的表型相关性中等（平均 0.46），与 NAb IgM 的相关性较弱（平均 0.01）。NAb 之间的遗传相关性估计也显示出类似的模式，但 SE 较小，估计 IgG NAb 平均为 0.76，IgM NAb 平均为 0.63，IgG 和 IgM NAb 之间为 0.17，总 IgG 和 IgG NAb 之间为 0.64，总 IgG 和 IgM NAb 之间为 0.13。表型上，存活的猪的 NAb 和总 IgG 水平略高于死亡的猪。从较低的死亡率和较少的全身抗生素治疗来看，遗传上，较高的 NAb 水平往往与更强的疾病弹性有关。对 NAb 滴度的全基因组关联分析确定了几个基因组区域，其中有几个与免疫反应相关的候选基因。
健康仔猪血液中的 NAb 水平是可遗传的，是对多微生物疾病弹性的潜在遗传指标。
