Genetic Diversity and Disease Resistance in Avian Major Histocompatibility Complex

The major histocompatibility complex (MHC) in birds is a highly polymorphic genomic region that governs antigen presentation and shapes adaptive immune responses. In chickens, a streamlined “minimal essential” MHC comprises a single dominantly expressed class I locus closely linked to antigen-processing genes, yielding strong haplotype associations with resistance or susceptibility to pathogens such as Marek’s disease virus and infectious bursal disease virus. In contrast, waterfowl and some passerines display expanded multigene MHC clusters with greater allelic diversity and broader peptide-binding repertoires, correlating with enhanced tolerance to highly pathogenic avian influenza and other viral infections. Mechanisms including gene duplication, recombination hotspots and gene conversion events continually generate novel alleles and haplotypes, maintaining diversity in wild and domestic populations. Insights into MHC architecture and function have guided selective breeding for disease resistance, informed vaccine design by pinpointing protective epitopes and supported conservation of indigenous ecotypes. Advances in long-read genome assembly, single nucleotide polymorphism panels and structural analyses of peptide-MHC complexes have refined our understanding of avian immunogenetics, offering practical approaches to bolster flock health, reduce zoonotic risks and preserve genetic resilience across diverse production systems.

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Genetic Diversity and Disease Resistance in Avian Major Histocompatibility Complex publication trend

The graph below shows the total number of articles in genetic diversity and disease resistance in avian major histocompatibility complex across all publications each year (not limited to Nature Index journals).

Technical terms

Major histocompatibility complex (MHC): A genomic region encoding cell-surface glycoproteins responsible for antigen presentation to T cells.

Allele: A variant form of a gene at a specific locus, differing in nucleotide sequence.

Haplotype: A set of alleles at adjacent loci on a chromosome inherited together.

Polymorphism: The occurrence of two or more genetically determined variants in a population.

Recombination hotspot: A genomic region where the frequency of crossover events during meiosis is elevated.

References

1. A new chromosome-scale duck genome shows a major histocompatibility complex with several expanded multigene families. BMC Biology (2024).
2. A high-density SNP panel reveals extensive diversity, frequent recombination and multiple recombination hotspots within the chicken major histocompatibility complex B region between BG2 and CD1A1. Genetics Selection Evolution (2016).
3. The peptide motif of the single dominantly expressed class I molecule of the chicken MHC can explain the response to a molecular defined vaccine of infectious bursal disease virus (IBDV). Immunogenetics (2013).
4. Genetic diversity of 10 indigenous chicken ecotypes from Southern Highlands of Tanzania based on Major Histocompatibility Complex-linked microsatellite LEI0258 marker typing. Poultry Science (2019).
5. Antigen processing and presentation: Evolution from a bird's eye view. Molecular Immunology (2012).
6. Structural Definition of Duck Major Histocompatibility Complex Class I Molecules That Might Explain Efficient Cytotoxic T Lymphocyte Immunity to Influenza A Virus. Journal of Virology (2017).