Institute of Parasitology, Vetsuisse-Faculty, University of Zurich, Winterthurerstrasse 266a, 8057 Zurich, Switzerland.
Institute of Parasitology, Vetsuisse-Faculty, University of Zurich, Winterthurerstrasse 266a, 8057 Zurich, Switzerland; Graduate School for Cellular and Biomedical Sciences, University of Bern, Switzerland.
Infect Genet Evol. 2021 Jan;87:104618. doi: 10.1016/j.meegid.2020.104618. Epub 2020 Nov 11.
Angiostrongylus vasorum is an emerging parasitic cardiopulmonary nematode of dogs, foxes, and other canids. In dogs, the infection causes respiratory and bleeding disorders along with other clinical signs collectively known as canine angiostrongylosis, while foxes represent an important wildlife reservoir. Despite the spread of A. vasorum across various countries in Europe and the Americas, little is known about the genetic diversity of A. vasorum populations at a local level in a highly endemic area. Thus, in the present study, we investigated the genetic diversity of 323 adult A. vasorum nematodes from 64 foxes living in the canton of Zurich, Switzerland. Among those, 279 worms isolated from 20 foxes were analyzed separately to investigate the genetic diversity of multiple worms within individual foxes. Part of the mitochondrial cytochrome c oxidase subunit I (mtCOI) gene was amplified and sequenced. Overall, 16 mitochondrial haplotypes were identified. The analysis of multiple worms per host revealed 12 haplotypes, with up to 5 different haplotypes in single individuals. Higher haplotype diversity (n = 10) of nematodes from foxes of urban areas than in rural areas (n = 7) was observed, with 5 shared haplotypes. Comparing our data with published GenBank sequences, five haplotypes were found to be unique within the Zurich nematode population. Interestingly, A. vasorum nematodes obtained from foxes in London and Zurich shared the same dominating haplotype. Further studies are needed to clarify if this haplotype has a different pathogenicity that may contribute to its dominance. Our findings show the importance of foxes as a reservoir for genetic parasite recombination and indicate that high fox population densities in urban areas with small and overlapping home ranges allow multiple infection events that lead to high genetic variability of A. vasorum.
血管圆线虫是一种新兴的犬、狐和其他犬科动物寄生性心肺线虫。在犬中，感染会导致呼吸和出血紊乱以及其他共同称为犬血管圆线虫病的临床症状，而狐则是重要的野生动物储存宿主。尽管血管圆线虫已在欧洲和美洲的多个国家传播，但在高度流行地区，对局部水平的血管圆线虫种群的遗传多样性知之甚少。因此，在本研究中，我们调查了来自瑞士苏黎世州的 64 只狐狸中 323 只成年血管圆线虫的遗传多样性。其中，从 20 只狐狸中分离出的 279 条蠕虫分别进行了分析，以研究单个狐狸体内的多条蠕虫的遗传多样性。部分线粒体细胞色素 c 氧化酶亚基 I（mtCOI）基因被扩增和测序。总体上，鉴定出 16 个线粒体单倍型。对每个宿主的多条蠕虫进行分析，发现了 12 个单倍型，单个个体中多达 5 个不同的单倍型。城市地区狐狸的线虫具有更高的单倍型多样性（n=10），而农村地区（n=7）的单倍型多样性较低，有 5 个共享单倍型。将我们的数据与已发表的 GenBank 序列进行比较，发现苏黎世线虫种群中有 5 个单倍型是独特的。有趣的是，从伦敦和苏黎世狐狸中获得的血管圆线虫具有相同的主导单倍型。需要进一步研究以确定这种单倍型是否具有不同的致病性，这可能导致其优势地位。我们的研究结果表明了狐狸作为遗传寄生虫重组储存宿主的重要性，并表明在人口密度高、家庭范围小且重叠的城市地区，狐狸种群密度高，允许多次感染事件发生，导致血管圆线虫遗传变异性高。
