title: Functional associations of similar MHC alleles and shared parasite species in two sympatric lemurs.
abstract: Several recent studies of animals in their natural surroundings found evidence for effects of certain major histocompatibility complex (MHC) immune gene alleles on the parasite load. However, in multi-infected individuals the particular selection pressure exerted by specific parasites has rarely been explored. In this study we took advantage of the parasitological and genetic data of two previously investigated Malagasy lemur species (Cheirogaleus medius and Microcebus murinus). We investigated whether the two sympatric and ecologically similar primates are infected by similar parasite species and explored if certain parasites are associated with particular MHC alleles. Our study revealed that most of the parasite egg morphotypes were found in both hosts. In each lemur species we identified one MHC allele which was positively associated with Ascaris-infection. Interestingly, these MHC alleles were very similar to each other but differed from all other investigated MHC alleles in an amino acid substitution in a putative functional important antigen binding site. Thus, our study gives first intriguing evidence for a direct connection between certain antigen binding sites of MHC molecules with a particular parasite in two wild primate populations. This may indicate that indeed certain parasites exert direct selective pressure on the MHC of wild living hosts.
authors.affiliation: Leibniz Institute for Zoo and Wildlife Research, Dept. Evolutionary Genetics, Alfred-Kowalke-Strasse 17, D-10315 Berlin, Germany.
authors.forename: Nina
authors.initials: N
authors.lastname: Schwensow
authors.forename: Kathrin
authors.initials: K
authors.lastname: Dausmann
authors.forename: Manfred
authors.initials: M
authors.lastname: Eberle
authors.forename: Joanna
authors.initials: J
authors.lastname: Fietz
authors.forename: Simone
authors.initials: S
authors.lastname: Sommer
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D014644:Genetic Variation; D007900:Lemur / Q000235:genetics / Q000276:immunology / Q000469:parasitology; D008270:Madagascar; D008285:Major Histocompatibility Complex / Q000235:genetics*; D008969:Molecular Sequence Data; D010270:Parasite Egg Count; D010271:Parasites; D010802:Phylogeny; D012641:Selection, Genetic / Q000235:genetics; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA