Ancient Hybridization and Adaptive Introgression of an Invadolysin Gene in Schistosome Parasites

Year: 2019

Type: article

Abstract: Introgression among parasite species has the potential to transfer traits of biomedical importance across species boundaries. The parasitic blood fluke Schistosoma haematobium causes urogenital schistosomiasis in humans across sub-Saharan Africa. Hybridization with other schistosome species is assumed to occur commonly, because genetic crosses between S. haematobium and livestock schistosomes, including S. bovis, can be staged in the laboratory, and sequencing of mtDNA and rDNA amplified from microscopic miracidia larvae frequently reveals markers from different species. However, the frequency, direction, age, and genomic consequences of hybridization are unknown. We hatched miracidia from eggs and sequenced the exomes from 96 individual S. haematobium miracidia from infected patients from Niger and the Zanzibar archipelago. These data revealed no evidence for contemporary hybridization between S. bovis and S. haematobium in our samples. However, all Nigerien S. haematobium genomes sampled show hybrid ancestry, with 3.3-8.2% of their nuclear genomes derived from S. bovis, providing evidence of an ancient introgression event that occurred at least 108-613 generations ago. Some S. bovis-derived alleles have spread to high frequency or reached fixation and show strong signatures of directional selection; the strongest signal spans a single gene in the invadolysin gene family (Chr. 4). Our results suggest that S. bovis/S. haematobium hybridization occurs rarely but demonstrate profound consequences of ancient introgression from a livestock parasite into the genome of S. haematobium, the most prevalent schistosome species infecting humans.

Source: Molecular Biology and Evolution

DOI: 10.1093/molbev/msz154

Authors: Roy N Platt, Marina McDew-White, Winka Le Clec’h, Frédéric D Chevalier, Fiona Allan, Aidan M Emery, Amadou Garba, Amina A Hamidou, Shaali M Ame, Joanne P Webster, David Rollinson, Bonnie L Webster, Timothy J C Anderson

Institutions: Texas Biomedical Research Institute, Natural History Museum, London Centre for Neglected Tropical Disease Research, Imperial College London, Public Health Laboratory Ivo de Carneri, University of London, Royal Veterinary College

Language: English

Topic: Parasites and Host Interactions

Subfield: Parasitology

Field: Immunology and Microbiology

Domain: Life Sciences

Open Access status: hybrid

Estimated APC paid: $3,418

Funders: Bill and Melinda Gates Foundation, University of Georgia, Wellcome Trust, Texas Biomedical Research Institute, National Institutes of Health, Defence Science and Technology Laboratory, University of Georgia Research Foundation, Medical Research Council, Biotechnology and Biological Sciences Research Council, Economic and Social Research Council, Natural Environment Research Council, National Institute of Allergy and Infectious Diseases, National Center for Research Resources, National Center for Advancing Translational Sciences

OpenAlex ID: W2955632442