Global selective sweep of a highly inbred genome of the cattle parasite Neospora caninum

Authors: KHAN, A - National Institutes Of Health (NIH); FUJITA, AW - National Institutes Of Health (NIH); RANDLE, N - University Of Liverpool; REGIDOR-CERRILLO, J - University Of Madrid; SHAIK, JS - National Institutes Of Health (NIH); SHEN, K - National Institutes Of Health (NIH); OLER, AJ - National Institutes Of Health (NIH); QUINONES, M - National Institutes Of Health (NIH); LATHAM, SM - University Of Liverpool; AKANMORI, BD - World Health Organization,congo Region; CLEAVELAND, S - University Of Glasgow; RYAN, U - Murdoch University; SLAPETA, J - University Of Sydney; SCHARES, G - Friedrich-Loeffler-institute; ORTEGA-MORA, LM - University Of Madrid; Dubey, Jitender; WASTLING, JM - University Of Liverpool; GRIGG, ME - National Institutes Of Health (NIH)

Submitted to: Nature Communications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/2019
Publication Date: 11/5/2019
Citation: Khan, A., Fujita, A., Randle, N., Regidor-Cerrillo, J., Shaik, J., Shen, K., Oler, A., Quinones, M., Latham, S., Akanmori, B., Cleaveland, S., Ryan, U., Slapeta, J., Schares, G., Ortega-Mora, L., Dubey, J.P., Wastling, J., Grigg, M. 2019. Global selective sweep of a highly inbred genome of the cattle parasite Neospora caninum. Nature Communications. 116(45):22764-22773. https://doi.org/10.1073/pnas.1913531116.
DOI: https://doi.org/10.1073/pnas.1913531116

Interpretive Summary: Toxoplasmosis, caused by the single celled parasite, Toxoplasma gondii, continues to be a public health probem. In addition to causing severe disease in humans, toxoplasmosis also causes abortions in livestock and mortality in many other hosts. Neosporosis, caused by a parasite Neospora caninum, is relatively a newly recognized entity. Until 1988, N. caninum was misdiagnosed as T. gondii. In 1988, J.P. Dubey (an ARS researcher) in collaboration with others, cultivated and named the parasite N. caninum. Neosporosis is now considered the most important cause of abortion in cattle worldwide. N. Caninum is is phylogenetically related to T. gondii but unlike T. gondii, N. Caninum is transmitted vertically from dam to offsprings. In the present paper scientist assessed data on N. Canimum genome and concluded that N. caninum population genetics is dominated by a single highly inbred genome that has expanded globally predominantly by unisexual mating and vertical transmission. This paper will be of interest to parasitologists, biologists and veterinarians.

Technical Abstract: Neospora caninum, a cyst forming Apicomplexan parasite, is a leading cause of neuromuscular diseases in dogs as well as fetopathy and abortion in cattle worldwide. The importance of the domestic and sylvatic life cycles of Neospora, and the role of vertical transmission in the expansion and transmission of infection in cattle is not sufficiently understood. To elucidate the population genomics of Neospora, we genotyped 50 isolates collected worldwide from a wide range of hosts using 19 linked and unlinked genetic markers. Phylogenetic analysis and genetic distance indexes resolved a single genotype of N. caninum. Whole genome sequencing of 7 isolates from two different continents identified high linkage disequilibrium, significant structural variation but only limited polymorphism genome-wide, with only 5,766 biallelic single nucleotide polymorphisms (SNPs) total. Greater than half of these SNPs (~3,000) clustered into six distinct haploblocks and each block possessed limited allelic diversity (with only 4-6 haplotypes resolved at each cluster). Importantly, the alleles at each haploblock had independently segregated across the strains sequenced, supporting a unisexual expansion model that is mosaic at six genomic blocks. Integrating seroprevalence data from African cattle, our data supports a global selective sweep of a highly inbred livestock pathogen that originated within European dairy stock and expanded trans-continentally via unisexual mating and vertical transmission very recently; likely the result of human activities, including recurrent migration, domestication, and breed development of bovid and canid hosts within similar proximities.