MHC and parasite-host coevolution

We investigate the variation of MHC (major histocompatibility complex) classII genes (MHII in teleosts) in perch (Oppelt et al. 2012). These genes belong to the most variable genomic regions in the vertebrate genome. Their high degree of polymorphism is maintained by parasite-host arms race, as MHC genes play a key role in the individual immune response against various pathogens. As such they are directly linked to the individual's fitness. In a variety of vertebrates MHC classII genes are involved in the identification of nonself antigens and induce the innate immune response against them. Additionally it has been shown that resistance against specific parasites can be linked to the presence of specific MHC classII exon2 alleles in human and pacific salmon. In several experiments it has been shown that MHC classII peptides also play a role in olfactory recognition. Some evidence from mice and fish studies showed that kin can be recognized based on MHC classII allele similarity and recently we found MHC to play a major role in olfactory imprinting in zebrafish (Hinz et al. 2013).

We have developed specific primers for MHII ß (Intron1 and exon2) genes of perch to investigate their diversity in perch of Lake Constance and reveal putative differences between populations. We found a high diversity both within and among individuals and several loci for MHII genes in perch (Michel et al. 2009). Currently, we have established a genotyping method that combines Exon2 specific PCR with an adjacent reference strand conformation analysis (RSCA) as a quick and economic tool to determine individual allelic compositions (Oppelt et al. 2012). In a first step we identify the specific parasite community (macro parasites) of perch from different localities in Lake Constance and combine these with investigations on individual MHC allele settings. Local differences in the parasite community and the individual MHC allele settings could indicate that MHC alleles indeed represent adaptive functional traits that are directly influenced by selection through parasites.

Michel C, Bernatchez, L, Behrmann-Godel J. (2009). Diversity and evolution of MHII β genes in a non-model percid species − the Eurasian perch (Perca fluviatilis L.) Molecular Immunology 46, 3399-3410

Oppelt C, Behrmann-Godel J. (2012). Genotyping MHC classIIB in non-model species by reference strand-mediated conformational analysis (RSCA). Conservation Genetics Resources. 4, 841-844.

Hinz C, Namekawa R, Behrmann-Godel J,Oppelt C, Jaechke A, Müller A, Friedrich RW, Gerlach G. (2013). Olfactory imprinting is triggered by MHC peptide ligands. Scientific Reports 3:2800 (doi: 10.1038/srep02800)

Björklund M, Aho T, Behrmann-Godel J. (2015). Isolation over 35 year in a heated biotest basin and selection on MHC class IIß genes in the European perch (Perca fluvaitilis L.). Ecology and Evolution Apr; 5(7):1440-1455.