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Use of developmental temperature and gastrointestinal tract location to isolate pure Trichostrongylus vitrinus from mixed, naturally acquired trichostrongylid infections in sheep
Author(s) -
Blackburn PJ,
Carmichael IH,
WalkdenBrown SW,
Greenslade S
Publication year - 2015
Publication title -
australian veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.382
H-Index - 59
eISSN - 1751-0813
pISSN - 0005-0423
DOI - 10.1111/avj.12325
Subject(s) - trichostrongylus , biology , feces , teladorsagia circumcincta , strain (injury) , microbiology and biotechnology , isolation (microbiology) , larva , gastrointestinal tract , veterinary medicine , anatomy , ecology , haemonchus contortus , medicine , biochemistry
Objective To isolate Trichostrongylus vitrinus from naturally‐acquired mixed trichostrongylid infections (predominantly Trichostrongylus spp. and Teladorsagia circumcincta ) in sheep using differential larval development temperatures and the anatomical location of adults. Methods Faeces were collected from ewes with mixed, naturally acquired trichostrongylid infection, and incubated at low temperatures (4°C or 8°C) for 20–68 days depending on temperature. Harvested infective larvae were passaged through worm‐free lambs, from which the first 5 m of small intestine was collected and adult worms recovered. Purity of infection with T . vitrinus was assessed by examination of spicules on 100 adult male worms. Eggs of recovered adult female worms were cultured at 25°C and harvested larvae were re‐passaged through worm‐free lambs. Results Low temperature incubation (≤8°C) successfully exploited variation in the developmental temperature required by pre‐parasitic stages of small intestinal nematodes, allowing T . vitrinus to develop while others did not. Differential organ harvest from infected sheep allowed isolation of T . vitrinus from other gastrointestinal nematodes, with amplification of pure T . vitrinus achieved by passage through a further generation of lambs. Conclusion A successful method for the isolation of pure T . vitrinus from mixed infections is described. The resulting pure strain of T . vitrinus has been amplified and is held by two institutions for use in research (CSIRO reference SARDI 2011 strain).