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Parasite virulence when the infection reduces the host immune response
Stéphane Cornet1, Gabriele Sorci
1UMR/Centre National de la Recherche Scentifique, 5561 Biogéosciences, Université de Bourgogne, 6 boulevard Gabriel, Dijon, France. stephane.cornet@u-bourgogne.fr
Proceedings. Biological Sciences
|March 5, 2010
Summary
Parasite infections weaken host immunity, increasing susceptibility to opportunistic diseases. This study shows that increased environmental pathogen exposure significantly raises mortality risk for infected amphipods, highlighting the role of environmental factors in parasite virulence.
Area of Science:
- Ecology
- Parasitology
- Evolutionary Biology
Background:
- Parasite infections often suppress host immune responses, aiding parasite establishment but increasing vulnerability to secondary infections.
- This immunodepression can limit parasite transmission by reducing host survival duration.
Purpose of the Study:
- To investigate how the risk of opportunistic infections influences the survival of Gammarus pulex infected with Pomphorhynchus laevis.
- To determine if parasite-induced immunodepression is modulated by environmental exposure to pathogens.
Main Methods:
- Gammarus pulex were experimentally infected with Pomphorhynchus laevis or kept as controls.
- Hosts were maintained in either clean or micro-organism-enriched water to simulate varying risks of opportunistic disease.
Main Results:
- Infected hosts in micro-organism-enriched water exhibited significantly higher mortality compared to infected hosts in clean water.
- Non-infected hosts showed only a moderate increase in mortality when exposed to micro-organism-enriched water.
- Parasite virulence is context-dependent, influenced by the environmental risk of opportunistic infections.
Conclusions:
- The virulence of P. laevis, which suppresses the immune response of G. pulex, is sensitive to environmental conditions.
- Increased mortality in infected hosts due to opportunistic pathogens represents a potential cost to the parasite.
- Optimal parasite exploitation strategies may depend on environmental factors and the associated risk of secondary infections.
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