title: MHC-I affects infection intensity but not infection status with a frequent avian malaria parasite in blue tits.
abstract: Host resistance against parasites depends on three aspects: the ability to prevent, control and clear infections. In vertebrates the immune system consists of innate and adaptive immunity. Innate immunity is particularly important for preventing infection and eradicating established infections at an early stage while adaptive immunity is slow, but powerful, and essential for controlling infection intensities and eventually clearing infections. Major Histocompatibility Complex (MHC) molecules are central in adaptive immunity, and studies on parasite resistance and MHC in wild animals have found effects on both infection intensity (parasite load) and infection status (infected or not). It seems MHC can affect both the ability to control infection intensities and the ability to clear infections. However, these two aspects have rarely been considered simultaneously, and their relative importance in natural populations is therefore unclear. Here we investigate if MHC class I genotype affects infection intensity and infection status with a frequent avian malaria infection Haemoproteus majoris in a natural population of blue tits Cyanistes caeruleus. We found a significant negative association between a single MHC allele and infection intensity but no association with infection status. Blue tits that carry a specific MHC allele seem able to suppress H. majoris infection intensity, while we have no evidence that this allele also has an effect on clearance of the H. majoris infection, a result that is in contrast with some previous studies of MHC and avian malaria. A likely explanation could be that the clearance rate of avian malaria parasites differs between avian malaria lineages and/or between avian hosts.
authors.affiliation: Department of Biology, Lund University, Lund, Sweden.
authors.forename: Helena
authors.initials: H
authors.lastname: Westerdahl
authors.forename: Martin
authors.initials: M
authors.lastname: Stjernman
authors.forename: Lars
authors.initials: L
authors.lastname: Råberg
authors.forename: Mimi
authors.initials: M
authors.lastname: Lannefors
authors.forename: Jan-Åke
authors.initials: JÅ
authors.lastname: Nilsson
mesh_terms: D000375:Aging / Q000276:immunology; D000483:Alleles; D000818:Animals; D005787:Gene Frequency / Q000235:genetics; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000276:immunology*; D006790:Host-Parasite Interactions / Q000276:immunology*; D008289:Malaria, Avian / Q000453:epidemiology / Q000235:genetics / Q000276:immunology* / Q000469:parasitology*; D046109:Passeriformes / Q000235:genetics / Q000254:growth & development / Q000276:immunology* / Q000469:parasitology*; D013548:Sweden / Q000453:epidemiology
chemical_list: D015395:Histocompatibility Antigens Class I
references.citation: Mol Ecol. 2010 Aug;19(16):3444-55
references.pmid: 20670363
references.citation: Ecol Lett. 2008 Mar;11(3):258-65
references.pmid: 18070099
references.citation: Proc Biol Sci. 2004 Nov 22;271(1555):2387-94
references.pmid: 15556892
references.citation: Proc Biol Sci. 2011 Apr 22;278(1709):1264-72
references.pmid: 20943698
references.citation: Proc Biol Sci. 2010 Apr 7;277(1684):979-88
references.pmid: 20071384
references.citation: Parasitology. 1996;112 Suppl:S75-84
references.pmid: 8684839
references.citation: PLoS One. 2008 Jun 18;3(6):e2463
references.pmid: 18560544
references.citation: Evolution. 2006 Feb;60(2):383-9
references.pmid: 16610328
references.citation: Immunogenetics. 2007 May;59(5):417-26
references.pmid: 17351770
references.citation: Proc Biol Sci. 2013 Mar 20;280(1759):20130134
references.pmid: 23516242
references.citation: Proc Biol Sci. 2012 Feb 7;279(1728):577-84
references.pmid: 21733902
references.citation: Evolution. 2005 Feb;59(2):439-50
references.pmid: 15807428
references.citation: Proc Biol Sci. 2005 Jul 22;272(1571):1511-8
references.pmid: 16011927
references.citation: J Evol Biol. 2010 Mar;23(3):557-69
references.pmid: 20070458
references.citation: PLoS One. 2011;6(7):e21905
references.pmid: 21779353
references.citation: Viruses. 2009 Sep;1(2):104-25
references.pmid: 21994541
references.citation: Proc Biol Sci. 2009 Sep 7;276(1670):3133-40
references.pmid: 19515657
references.citation: Science. 1977 Jan 14;195(4274):193-5
references.pmid: 831269
references.citation: Nat Genet. 1998 Feb;18(2):192-4
references.pmid: 9462755
references.citation: Proc Biol Sci. 2000 Aug 7;267(1452):1583-9
references.pmid: 11007335
references.citation: Proc Biol Sci. 2009 Mar 22;276(1659):1119-28
references.pmid: 19129114
references.citation: Heredity (Edinb). 2004 Jun;92(6):534-42
references.pmid: 15162116
references.citation: Exp Parasitol. 2008 May;119(1):99-110
references.pmid: 18280472
references.citation: Heredity (Edinb). 2006 Jan;96(1):7-21
references.pmid: 16094301
references.citation: Nature. 2010 May 20;465(7296):350-4
references.pmid: 20445539
references.citation: Proc Natl Acad Sci U S A. 1998 Mar 31;95(7):3714-9
references.pmid: 9520432
references.citation: Mol Biol Evol. 2005 May;22(5):1254-9
references.pmid: 15703235
references.citation: Mol Ecol. 2010 Oct;19(19):4155-67
references.pmid: 20723049
references.citation: Mol Ecol. 2010 Mar;19 Suppl 1:255-65
references.pmid: 20331784
references.citation: Genetics. 2005 Jul;170(3):1427-30
references.pmid: 15911576
references.citation: Proc Natl Acad Sci U S A. 2012 Feb 28;109(9):3422-7
references.pmid: 22323587
references.citation: Genetica. 2012 Sep;140(7-9):349-64
references.pmid: 23073914
references.citation: Immunogenetics. 2011 Feb;63(2):103-13
references.pmid: 20924575
references.citation: Mol Ecol. 2012 May;21(10):2469-79
references.pmid: 22512812
references.citation: Immunogenetics. 2011 Aug;63(8):531-42
references.pmid: 21559782
references.citation: Parasitology. 2012 Sep;139(10):1246-52
references.pmid: 22716664
references.citation: J Gen Virol. 2010 Oct;91(Pt 10):2507-12
references.pmid: 20573856
references.citation: Exp Parasitol. 2011 Feb;127(2):527-33
references.pmid: 21050849
references.citation: PLoS Genet. 2009 Dec;5(12):e1000791
references.pmid: 20041166
references.citation: Proc Natl Acad Sci U S A. 2011 Oct 4;108(40):16705-10
references.pmid: 21949385