Large lungworms (Nematoda: Dictyocaulidae) recovered from the European bison may represent a new nematode subspecies

Abstract

Although the Dictyocaulus lungworm, the agent of dictyocaulosis, is one of parasitological threats to European bison, its systematic position remains unclear. The aim of the present study was to evaluate the morphological features of the lungworm and the pathological lesions it induces, and to analyse mitochondrial ( mt ) genetic markers for systematic and molecular epidemiological studies. The morphological findings indicate that Dictyocaulus lungworms of European bison can be distinguished from those of cattle on the basis of differences in buccal capsule wall length, total body length, and spicules length in males, all of which were significantly longer in those of European bison. Nucleotide diversity calculated from pairwise sequence alignments of partial cytochrome c oxidase subunit 1 ( cox 1), cytochrome B ( cyt B) and NADH dehydrogenase subunit 5 ( nad 5) of specimens from cattle and European bison varied from 1.7% for nad 5, 2.1% for cyt B, to 3.7% for cox 1 gene. Thus, among the lungworms of European bison and cattle, nad 5 and cyt B were the most conserved proteins, whereas cox 1 was the most diverse. The mt cyt B marker gene may be a suitable candidate for distinguishing between the two genotypes, as nad 5 demonstrated the greatest within-genus sequence variation. The lung tissue of infected European bison manifests signs of verminous pneumonia characterized by interstitial pneumonia, bronchitis and bronchiolitis. Therefore, it appears that European bison and cattle are infected with slightly diverged, morphologically-different, genotypes of D. viviparus , indicating they belong to two separate worm populations. We propose, therefore, that the lungworm of European bison should be classified as D. viviparus subsp. bisontis .

Contact between European bison and cattle from the cattle breeders’ perspective, in the light of the risk of pathogen transmission

“…Another parasite, Ashworthius sidemi , is an alien species that was first introduced to Polish wildlife with migrating Asian cervids, and then transferred to the Czech Republic with European bison translocated from Poland [ 46 , 47 ]. Pasture sharing can also lead to transmission of lungworm larvae ( Dictyocaulus viviparus ) between animals; although the parasite demonstrates some genetic variability, it belongs to a single species [ 37 , 48 – 50 ]. In addition, eyeworm infestations by the spirurid nematodes Thelazia gulosa and T .…”

Characterization of the mitochondrial genome of Tetrameres grusi and insights into the phylogeny of Spirurina

“…Mitochondrial genomes (mitogenomes) have maternal inheritance, an apparent lack of recombination, rapid evolutionary rates and comparatively conserved genomic structures ( Pyziel et al, 2020 ). Recently, sequences of whole mitogenomes have been used to infer phylogenetic relationships among parasites at different taxonomic levels ( Gao et al, 2021 ).…”

Opening a can of lungworms: Molecular characterization of Dictyocaulus (Nematoda: Dictyocaulidae) infecting North American bison (Bison bison)

“…The most recent revision of the genus Dictyocaulus also failed to recognize D. hadweni as a valid species ( Gibbons and Khalil, 1988 ). Nevertheless, the morphological differentiation among adult male and female can be rather challenging, and recent studies integrating classical and molecular approaches have recognized two new species in Eurasian cervids, namely D. capreolus and D. cervi , and a proposed susbspecies infecting the European bison, D. v. viviparus ( Gibbons and Khalil, 1988 ; Gibbons and Höglund, 2002 ; Pyziel et al, 2017 , 2020 ). Overall, these recent advances around the biodiversity of the genus Dictyocaulus suggest that cryptic species may yet to be recognized, especially since our analysis identified a previously uncharacterized species genetically distinct from both D. viviparus and the proposed subspecies D. v. bisontis described in European bison ( Pyziel et al, 2020 ).…”