Filarial parasites develop faster and reproduce earlier in response to host immune effectors that determine filarial life expectancy

Babayan, S.A. , Read, A.F., Lawrence, R.A., Bain, O. and Allen, J.E. (2010) Filarial parasites develop faster and reproduce earlier in response to host immune effectors that determine filarial life expectancy. PLoS Biology, 8(10), e1000525. (doi:10.1371/journal.pbio.1000525)

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Abstract

Humans and other mammals mount vigorous immune assaults against helminth parasites, yet there are intriguing reports that the immune response can enhance rather than impair parasite development. It has been hypothesized that helminths, like many free-living organisms, should optimize their development and reproduction in response to cues predicting future life expectancy. However, immune-dependant development by helminth parasites has so far eluded such evolutionary explanation. By manipulating various arms of the immune response of experimental hosts, we show that filarial nematodes, the parasites responsible for debilitating diseases in humans like river blindness and elephantiasis, accelerate their development in response to the IL-5 driven eosinophilia they encounter when infecting a host. Consequently they produce microfilariae, their transmission stages, earlier and in greater numbers. Eosinophilia is a primary host determinant of filarial life expectancy, operating both at larval and at late adult stages in anatomically and temporally separate locations, and is implicated in vaccine-mediated protection. Filarial nematodes are therefore able to adjust their reproductive schedules in response to an environmental predictor of their probability of survival, as proposed by evolutionary theory, thereby mitigating the effects of the immune attack to which helminths are most susceptible. Enhancing protective immunity against filarial nematodes, for example through vaccination, may be less effective at reducing transmission than would be expected and may, at worst, lead to increased transmission and, hence, pathology.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Babayan, Dr Simon
Authors: Babayan, S.A., Read, A.F., Lawrence, R.A., Bain, O., and Allen, J.E.
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
Journal Name:PLoS Biology
Publisher:Public Library of Science
ISSN:1544-9173
ISSN (Online):1544-9173
Copyright Holders:Copyright © 2010 The Authors
First Published:First published in PLoS Biology 8(10):e1000525
Publisher Policy:Reproduced under a Creative Commons License

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