title: Density-dependent immune responses against the gastrointestinal nematode Strongyloides ratti.
abstract: Negative density-dependent effects on the fitness of parasite populations are an important force in their population dynamics. For the parasitic nematode Strongyloides ratti, density-dependent fitness effects require the rat host immune response. By analysis of both measurements of components of parasite fitness and of the host immune response to different doses of S. ratti infection, we have identified specific parts of the host immune response underlying the negative density-dependent effects on the fitness of S. ratti. The host immune response changes both qualitatively from an inflammatory Th1- to a Th2-type immune profile and the Th2-type response increases quantitatively, as the density of S. ratti infection increases. Parasite survivorship was significantly negatively related to the concentration of parasite-specific IgG(1) and IgA, whereas parasite fecundity was significantly negatively related to the concentration of IgA only.
authors.affiliation: School of Biological Sciences, University of Bristol, Bristol, UK. colin.bleay@bristol.ac.uk
authors.forename: Colin
authors.initials: C
authors.lastname: Bleay
authors.forename: Clare P
authors.initials: CP
authors.lastname: Wilkes
authors.forename: Steve
authors.initials: S
authors.lastname: Paterson
authors.forename: Mark E
authors.initials: ME
authors.lastname: Viney
mesh_terms: D000818:Animals; D005260:Female; D005298:Fertility; D006790:Host-Parasite Interactions; D018928:Immunity, Mucosal; D007070:Immunoglobulin A / Q000032:analysis; D007074:Immunoglobulin G / Q000032:analysis; D007378:Interleukins / Q000032:analysis; D007411:Intestinal Diseases, Parasitic / Q000276:immunology* / Q000469:parasitology; D009349:Nematode Infections / Q000276:immunology* / Q000469:parasitology; D051381:Rats; D017208:Rats, Wistar; D017170:Strongyloides ratti / Q000276:immunology* / Q000472:pathogenicity; D018417:Th1 Cells / Q000276:immunology; D018418:Th2 Cells / Q000276:immunology
chemical_list: D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007378:Interleukins