title: An immunological marker of tolerance to infection in wild rodents.
abstract: Hosts are likely to respond to parasitic infections by a combination of resistance (expulsion of pathogens) and tolerance (active mitigation of pathology). Of these strategies, the basis of tolerance in animal hosts is relatively poorly understood, with especially little known about how tolerance is manifested in natural populations. We monitored a natural population of field voles using longitudinal and cross-sectional sampling modes and taking measurements on body condition, infection, immune gene expression, and survival. Using analyses stratified by life history stage, we demonstrate a pattern of tolerance to macroparasites in mature compared to immature males. In comparison to immature males, mature males resisted infection less and instead increased investment in body condition in response to accumulating burdens, but at the expense of reduced reproductive effort. We identified expression of the transcription factor Gata3 (a mediator of Th2 immunity) as an immunological biomarker of this tolerance response. Time series data for individual animals suggested that macroparasite infections gave rise to increased expression of Gata3, which gave rise to improved body condition and enhanced survival as hosts aged. These findings provide a clear and unexpected insight into tolerance responses (and their life history sequelae) in a natural vertebrate population. The demonstration that such responses (potentially promoting parasite transmission) can move from resistance to tolerance through the course of an individual's lifetime emphasises the need to incorporate them into our understanding of the dynamics and risk of infection in the natural environment. Moreover, the identification of Gata3 as a marker of tolerance to macroparasites raises important new questions regarding the role of Th2 immunity and the mechanistic nature of the tolerance response itself. A more manipulative, experimental approach is likely to be valuable in elaborating this further.
authors.affiliation: IBERS, Aberystwyth University, Aberystwyth, United Kingdom.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Jackson
authors.affiliation: School of Life Sciences, The University of Nottingham, Nottingham, United Kingdom.
authors.forename: Amy J
authors.initials: AJ
authors.lastname: Hall
authors.affiliation: School of Life Sciences, The University of Nottingham, Nottingham, United Kingdom; Institute of Integrative Biology, The University of Liverpool, Liverpool, United Kingdom.
authors.forename: Ida M
authors.initials: IM
authors.lastname: Friberg
authors.affiliation: School of Life Sciences, The University of Nottingham, Nottingham, United Kingdom.
authors.forename: Catriona
authors.initials: C
authors.lastname: Ralli
authors.affiliation: School of Life Sciences, The University of Nottingham, Nottingham, United Kingdom.
authors.forename: Ann
authors.initials: A
authors.lastname: Lowe
authors.affiliation: Institute of Integrative Biology, The University of Liverpool, Liverpool, United Kingdom.
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Zawadzka
authors.affiliation: Institute of Integrative Biology, The University of Liverpool, Liverpool, United Kingdom.
authors.forename: Andrew K
authors.initials: AK
authors.lastname: Turner
authors.affiliation: IBERS, Aberystwyth University, Aberystwyth, United Kingdom.
authors.forename: Alexander
authors.initials: A
authors.lastname: Stewart
authors.affiliation: School of Environment and Life Sciences, University of Salford, Salford, United Kingdom.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Birtles
authors.affiliation: Institute of Integrative Biology, The University of Liverpool, Liverpool, United Kingdom.
authors.forename: Steve
authors.initials: S
authors.lastname: Paterson
authors.affiliation: School of Life Sciences, The University of Nottingham, Nottingham, United Kingdom.
authors.forename: Janette E
authors.initials: JE
authors.lastname: Bradley
authors.affiliation: Institute of Integrative Biology, The University of Liverpool, Liverpool, United Kingdom.
authors.forename: Mike
authors.initials: M
authors.lastname: Begon
mesh_terms: D000818:Animals; D000835:Animals, Wild; D003411:Arvicolinae / Q000276:immunology*; D003430:Cross-Sectional Studies; D050990:GATA3 Transcription Factor / Q000096:biosynthesis; D006790:Host-Parasite Interactions; D007108:Immune Tolerance / Q000502:physiology*; D008137:Longitudinal Studies; D008297:Male; D010272:Parasitic Diseases / Q000276:immunology
chemical_list: D050990:GATA3 Transcription Factor