Support for the minimal essential MHC hypothesis: a parrot with a single, highly polymorphic MHC class II B gene

We characterized the MHC class II B gene in the green-rumped parrotlet, Forpus passerinus. Three approaches were used: polymerase chain reaction amplification using primers complementary to conserved regions of exon 2, sequencing clones from a genomic library, and amplification of exon 2 using speci...

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Bibliographic Details
Published in:Immunogenetics (New York) 2008-05, Vol.60 (5), p.219-231
Main Authors: Hughes, Colin R, Miles, Shana, Walbroehl, Jaclyn M
Format: Article
Language:English
Subjects:
alleles
Allergology
Amino Acid Sequence
Animals
Biomedical and Life Sciences
Biomedicine
Birds
Cell Biology
Cloning
evolution
Gene Function
Genes
Genotype & phenotype
Haplotypes
Histocompatibility Antigens Class II - genetics
Human Genetics
Hypotheses
Immunology
Infectious diseases
Lymphocytes
MHC class II
Models, Genetic
Molecular Sequence Data
Original Paper
parrots
Parrots - genetics
Peptides
Polymorphic
Polymorphism
Polymorphism, Genetic
Proteins
Species Specificity
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Summary:We characterized the MHC class II B gene in the green-rumped parrotlet, Forpus passerinus. Three approaches were used: polymerase chain reaction amplification using primers complementary to conserved regions of exon 2, sequencing clones from a genomic library, and amplification of exon 2 using species-specific primers. All three methods indicate that there is only a single class II B locus in this species and no pseudogenes. We suggest that this is the ancestral state for birds. The gene is highly polymorphic; 33 alleles were found in a sample of 25 individuals. Variation in exon 2 is concentrated in the peptide binding residues which show a significant excess of non-synonymous substitutions consistent with the operation of selection in maintaining this extraordinary polymorphism. Genomic clones show that major histocompatibility complex (MHC) gene organization is different from that of chickens; the class II A locus is close to II B. These data provide support for the hypothesis that the bird MHC constitutes a “minimal essential MHC” for responding to infectious disease.
ISSN:0093-7711
1432-1211
DOI:10.1007/s00251-008-0287-1