Rehman Zia Ur, Zahid Osama, Rashid Imran, Ali Qasim, Akbar Muhammad Haroon, Oneeb Muhammad, Shehzad Wasim, Ashraf Kamran, Sargison Neil D, Chaudhry Umer
Department of Parasitology, University of Veterinary and Animal Sciences Lahore, Punjab, Pakistan.
University of Edinburgh, Royal (Dick) School of Veterinary Studies and Roslin Institute, Easter Bush Veterinary Centre, Midlothian, Scotland EH25 9RG, UK.
Parasitol Int. 2020 Jun;76:102071. doi: 10.1016/j.parint.2020.102071. Epub 2020 Feb 8.
Fasciola spp. are responsible for over 3 billion US dollars of production loss annually in livestock and cause widespread zoonotic disease. Nevertheless, understating of the emergence and spread of the trematode species is poor. The multiplicity of F. gigantica infection and its spread is potentially influenced by multiple factors, including the abundance of suitable intermediate hosts, climatic conditions favouring the completion of the parasite's lifecycle, and translocation of infected animals, or free-living parasite stages between regions. Here we describe the development of a 'tremabiome' metabarcoding sequencing method to explore the numbers of F. gigantica genotypes per infection and patterns of parasite spread, based on genetic characteristics of the mitochondrial NADH dehydrogenase 1 (mt-ND-1) locus. We collected F. gigantica from three abattoirs in the Punjab and Balochistan provinces of Pakistan, and our results show a high level of genetic diversity in 20 F. gigantica populations derived from small and large ruminants consigned to slaughter in both provinces. This implies that F. gigantica can reproduce in its definitive hosts through meiosis involving cross- and self-breeding, as described in the closely related species, Fasciola hepatica. The genetic diversity between the 20 populations derived from different locations also illustrates the impact of animal movements on gene flow. Our results demonstrate the predominance of single haplotypes, consistent with a single introduction of F. gigantica infection in 85% of the hosts from which the parasite populations were derived. This is consistent with clonal reproduction in the intermediate snail hosts.
片形吸虫每年给家畜造成超过30亿美元的生产损失，并引发广泛的人畜共患病。然而，人们对这种吸虫物种的出现和传播了解甚少。巨片形吸虫感染的多样性及其传播可能受多种因素影响，包括合适中间宿主的数量、有利于寄生虫完成生命周期的气候条件，以及感染动物的转移或寄生虫在不同区域间自由生活阶段的转移。在此，我们基于线粒体烟酰胺腺嘌呤二核苷酸脱氢酶1（mt-ND-1）基因座的遗传特征，描述了一种“吸虫生物群落”宏条形码测序方法的开发，以探究每次感染中巨片形吸虫基因型的数量以及寄生虫的传播模式。我们从巴基斯坦旁遮普省和俾路支省的三个屠宰场收集了巨片形吸虫，结果显示，来自这两个省份待宰的小反刍动物和大反刍动物的20个巨片形吸虫种群具有高度的遗传多样性。这意味着，正如在其近缘物种肝片形吸虫中所描述的那样，巨片形吸虫可以通过涉及杂交和自交的减数分裂在其终末宿主中繁殖。来自不同地点的20个种群之间的遗传多样性也说明了动物移动对基因流动的影响。我们的结果表明单倍型占主导地位，这与85%的寄生虫种群所源自的宿主中巨片形吸虫感染为单次引入一致。这与中间螺宿主中的克隆繁殖相符。
