Callaby R, Hanotte O, Conradie Van Wyk I, Kiara H, Toye P, Mbole-Kariuki M N, Jennings A, Thumbi S M, Coetzer J A W, de C Bronsvoort B M, Knott S A, Woolhouse M E J, Kruuk L E B
Institute of Evolutionary Biology, University of Edinburgh, Ashworth Laboratories,Kings Buildings, West Mains Road, Edinburgh EH9 3JT,UK.
School of Life Sciences, University of Nottingham,University Park, Nottingham NG7 2RD,UK.
Parasitology. 2015 Mar;142(3):499-511. doi: 10.1017/S0031182014001498. Epub 2014 Sep 26.
Parasite burden varies widely between individuals within a population, and can covary with multiple aspects of individual phenotype. Here we investigate the sources of variation in faecal strongyle eggs counts, and its association with body weight and a suite of haematological measures, in a cohort of indigenous zebu calves in Western Kenya, using relatedness matrices reconstructed from single nucleotide polymorphism (SNP) genotypes. Strongyle egg count was heritable (h(2) = 23.9%, s.e. = 11.8%) and we also found heritability of white blood cell counts (WBC) (h(2) = 27.6%, s.e. = 10.6%). All the traits investigated showed negative phenotypic covariances with strongyle egg count throughout the first year: high worm counts were associated with low values of WBC, red blood cell count, total serum protein and absolute eosinophil count. Furthermore, calf body weight at 1 week old was a significant predictor of strongyle EPG at 16-51 weeks, with smaller calves having a higher strongyle egg count later in life. Our results indicate a genetic basis to strongyle EPG in this population, and also reveal consistently strong negative associations between strongyle infection and other important aspects of the multivariate phenotype.
在一个群体中，个体之间的寄生虫负荷差异很大，并且可能与个体表型的多个方面共同变化。在这里，我们利用从单核苷酸多态性（SNP）基因型重建的亲缘关系矩阵，研究了肯尼亚西部一群本地瘤牛犊粪便中圆线虫卵计数的变异来源，及其与体重和一系列血液学指标的关联。圆线虫卵计数具有遗传性（h(2)=23.9%，标准误=11.8%），我们还发现白细胞计数（WBC）具有遗传性（h(2)=27.6%，标准误=10.6%）。在第一年中，所有研究的性状与圆线虫卵计数均表现出负表型协方差：高虫数与低白细胞计数、红细胞计数、总血清蛋白和绝对嗜酸性粒细胞计数相关。此外，1周龄时犊牛的体重是16至51周龄时圆线虫每克粪便虫卵数（EPG）的重要预测指标，较小的犊牛在生命后期圆线虫卵计数较高。我们的结果表明该群体中圆线虫EPG存在遗传基础，并且还揭示了圆线虫感染与多变量表型的其他重要方面之间始终存在强烈的负相关。
