title: Tolerance and resistance to a nematode challenge are not always mutually exclusive.
abstract: The relationship between the manifestations of tolerance (a host's ability to reduce the impact of a given level of pathogens) and resistance (a host's ability to clear pathogens) has been assumed to be an antagonistic one. Here we tested the hypothesis that mice from strains more resistant to intestinal nematodes will experience reduced tolerance compared with less resistant mice. Three inbred strains of mice were used: C57BL/6 mice have been characterised as susceptible, whereas BALB/c and NIH mice have been characterised as resistant to Heligmosomoides bakeri infection. Mice of each strain were either parasitised with a single dose of 250 L3H. bakeri (n=10) in water or were sham-infected with water (n=10). Body weight, food intake and worm egg output were recorded regularly throughout the experiment. Forty-two days p.i. mice were euthanised and organ weights, eggs in colon and worm counts were determined. C57BL/6 mice showed significantly greater worm egg output (P<0.001), eggs in colon (P<0.05) and female worm fecundity (P<0.05) compared with NIH and BALB/c mice. Parasitised BALB/c mice grew more whilst parasitised C57BL/6 mice grew less than their sham-infected counterparts during the first 2 weeks post-challenge (P=0.05). Parasitism significantly increased liver, spleen, small intestine and caecum weights (P<0.001) but reduced carcass weight (P<0.01). Average daily weight gain and worm numbers were positively correlated in NIH mice (P=0.05); however, the relationship was reversed when carcass weight was used as a measure for tolerance. BALB/c mice did not appear to suffer from the consequences of parasitism, with carcass weight similar in all animals. Our hypothesis that strains more resistant to the H. bakeri infection are less tolerant compared with less resistant strains is rejected, as the two resistant strains showed variable tolerance. Thus, tolerance and resistance to an intestinal nematode infection are not always mutually exclusive.
authors: Disease Systems, Scotland's Rural College (SRUC), Easter Bush, Midlothian EH25 9RG, United Kingdom. Electronic address: spiridoula.athanasiadou@sruc.ac.uk.
authors: Spiridoula
authors: S
authors: Athanasiadou
authors: Disease Systems, Scotland's Rural College (SRUC), Easter Bush, Midlothian EH25 9RG, United Kingdom; Department of Chemistry, College of Natural and Computational Science, Hawassa University, P.O. Box 05, Hawassa, Ethiopia.
authors: Ketema
authors: K
authors: Tolossa
authors: School of Veterinary Medicine, Hawassa University, P.O. Box 05, Hawassa, Ethiopia.
authors: Etana
authors: E
authors: Debela
authors: School of Animal and Range Science, College of Agriculture, Hawassa University, P.O. Box 222, Hawassa, Ethiopia.
authors: Adugna
authors: A
authors: Tolera
authors: Disease Systems, Scotland's Rural College (SRUC), Easter Bush, Midlothian EH25 9RG, United Kingdom.
authors: Jos G M
authors: JG
authors: Houdijk
mesh_terms: D000825:Animal Structures / Q000469:parasitology / Q000473:pathology; D000818:Animals; D001835:Body Weight; D060467:Disease Resistance; D005260:Female; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009351:Nematospiroides dubius / Q000254:growth & development*; D010270:Parasite Egg Count; D059208:Parasite Load; D017206:Strongylida Infections / Q000276:immunology* / Q000469:parasitology* / Q000473:pathology
keywords: Genetic resistance; Heligmosomoides bakeri; Infection tolerance; Mice; Nematodes; Performance