title: Host origin determines pH tolerance of Tritrichomonas foetus isolates from the feline gastrointestinal and bovine urogenital tracts.
abstract: The ability for protozoan parasites to tolerate pH fluctuations within their niche is critical for the establishment of infection and require the parasite to be capable of adapting to a distinct pH range. We used two host adapted Tritrichomonas foetus isolates, capable of infecting either the digestive tract (pH 5.3-6.6) of feline hosts or the reproductive tract (pH 7.4-7.8) of bovine hosts to address their adaptability to changing pH. Using flow cytometry, we investigated the pH tolerance of the bovine and feline T. foetus isolates over a range of physiologically relevant pH in vitro. Following exposure to mild acid stress (pH 6), the bovine T. foetus isolates showed a significant decrease in cell viability and increased cytoplasmic granularity (p-value < 0.003, p-value < 0.0002) compared to pH 7 and 8 (p-value > 0.7). In contrast, the feline genotype displayed an enhanced capacity to maintain cell morphology and viability (p-value > 0.05). Microscopic assessment revealed that following exposure to a weak acidic stress (pH 6), the bovine T. foetus transformed into rounded parasites with extended cell volumes and displays a decrease in viability. The higher tolerance for acidic extracellular environment of the feline isolate compared to the bovine isolate suggests that pH could be a critical factor in regulating T. foetus infections and host-specificity.
authors.affiliation: Faculty of Veterinary Science, University of Sydney, NSW, Australia.
authors.forename: Victoria
authors.initials: V
authors.lastname: Morin-Adeline
authors.affiliation: Disciplines of Physiology, Anatomy & Histology, School of Medical Sciences, University of Sydney, NSW, Australia.
authors.forename: Stuart T
authors.initials: ST
authors.lastname: Fraser
authors.affiliation: School of Science and Health, University of Western Sydney, NSW, Australia.
authors.forename: Colin
authors.initials: C
authors.lastname: Stack
authors.affiliation: Faculty of Veterinary Science, University of Sydney, NSW, Australia. Electronic address: jan.slapeta@sydney.edu.au.
authors.forename: Jan
authors.initials: J
authors.lastname: Šlapeta
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D002371:Cat Diseases / Q000469:parasitology*; D002415:Cats; D002417:Cattle; D002418:Cattle Diseases / Q000469:parasitology*; D005434:Flow Cytometry / Q000662:veterinary; D005456:Fluorescent Dyes; D041981:Gastrointestinal Tract / Q000737:chemistry / Q000469:parasitology*; D005838:Genotype; D006790:Host-Parasite Interactions; D006863:Hydrogen-Ion Concentration; D046529:Microscopy, Electron, Transmission / Q000662:veterinary; D011529:Protozoan Infections, Animal / Q000469:parasitology*; D016835:Tritrichomonas foetus / Q000302:isolation & purification / Q000502:physiology* / Q000648:ultrastructure; D014566:Urogenital System / Q000737:chemistry / Q000469:parasitology*
chemical_list: D005456:Fluorescent Dyes
keywords: Host-switching; Host–parasite interaction; Trichomonads; Tritrichomonas foetus; pH regulation; pH tolerance