title: Impact of nest sanitation on the immune system of parents and nestlings in a passerine bird.
abstract: Bacterial communities are thought to have fundamental effects on the growth and development of nestling birds. The antigen exposure hypothesis suggests that, for both nestlings and adult birds, exposure to a diverse range of bacteria would select for stronger immune defences. However, there are relatively few studies that have tested the immune/bacterial relationships outside of domestic poultry. We therefore sought to examine indices of immunity (microbial killing ability in naive birds, which is a measure of innate immunity, and the antibody response to sheep red blood cells, which measures adaptive immunity) in both adult and nestling zebra finches (Taeniopygia guttata). We did this throughout breeding and between reproductive attempts in nests that were experimentally manipulated to change the intensity of bacterial exposure. Our results suggest that nest sanitation and bacterial load affected measures of the adaptive immune system, but not the innate immune parameters tested. Adult finches breeding in clean nests had a lower primary antibody response to sheep red blood cells, particularly males, and a greater difference between primary and secondary responses. Adult microbial killing of Escherichia coli decreased as parents moved from incubation to nestling rearing for both nest treatments; however, killing of Candida albicans remained consistent throughout. In nestlings, both innate microbial killing and the adaptive antibody response did not differ between nest environments. Together, these results suggest that exposure to microorganisms in the environment affects the adaptive immune system in nesting birds, with exposure upregulating the antibody response in adult birds.
authors.affiliation: Department of Biological Sciences, Macquarie University, Sydney, NSW 2109, Australia Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Geelong, VIC 3217, Australia Jessica.evans@deakin.edu.au.
authors.forename: Jessica K
authors.identifier: 0000-0003-0900-5636
authors.initials: JK
authors.lastname: Evans
authors.affiliation: Department of Biological Sciences, Macquarie University, Sydney, NSW 2109, Australia.
authors.forename: Simon C
authors.initials: SC
authors.lastname: Griffith
authors.affiliation: Department of Animal Science, University of California, 1 Shields Avenue, Davis, CA 95616, USA.
authors.forename: Kirk C
authors.initials: KC
authors.lastname: Klasing
authors.affiliation: Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Geelong, VIC 3217, Australia.
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Buchanan
mesh_terms: D056704:Adaptive Immunity; D000818:Animals; D000917:Antibody Formation; D058491:Bacterial Load; D002176:Candida albicans / Q000502:physiology; D004912:Erythrocytes; D004926:Escherichia coli / Q000502:physiology; D005260:Female; D046369:Finches / Q000276:immunology / Q000382:microbiology* / Q000502:physiology*; D007113:Immunity, Innate; D008297:Male; D064307:Microbiota / Q000276:immunology*; D009425:Nesting Behavior; D012756:Sheep
keywords: Avian immunity; Cell-mediated; Humoral; Microbiome; Microorganism; Sheep red blood cell