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Only rare classical MHC-I alleles are highly expressed in the European house sparrow

Watson, Hannah LU ; Drews, Anna LU ; Skogsmyr, Kelly Hultman LU ; Neto, Júlio Manuel LU ; Roved, Jacob LU and Westerdahl, Helena LU (2024) In Proceedings of the Royal Society B: Biological Sciences 291(2017).
Abstract

The exceptional polymorphism observed within genes of the major histocompatibility complex (MHC), a core component of the vertebrate immune system, has long fascinated biologists. The highly polymorphic classical MHC class-I (MHC-I) genes are maintained by pathogen-mediated balancing selection (PMBS), as shown by many sites subject to positive selection, while the more monomorphic non-classical MHC-I genes show signatures of purifying selection. In line with PMBS, at any point in time, rare classical MHC alleles are more likely than common classical MHC alleles to confer a selective advantage in host–pathogen interactions. Combining genomic and expression data from the blood of wild house sparrows Passer domesticus, we found that only... (More)

The exceptional polymorphism observed within genes of the major histocompatibility complex (MHC), a core component of the vertebrate immune system, has long fascinated biologists. The highly polymorphic classical MHC class-I (MHC-I) genes are maintained by pathogen-mediated balancing selection (PMBS), as shown by many sites subject to positive selection, while the more monomorphic non-classical MHC-I genes show signatures of purifying selection. In line with PMBS, at any point in time, rare classical MHC alleles are more likely than common classical MHC alleles to confer a selective advantage in host–pathogen interactions. Combining genomic and expression data from the blood of wild house sparrows Passer domesticus, we found that only rare classical MHC-I alleles were highly expressed, while common classical MHC-I alleles were lowly expressed or not expressed. Moreover, highly expressed rare classical MHC-I alleles had more positively selected sites, indicating exposure to stronger PMBS, compared with lowly expressed classical alleles. As predicted, the level of expression was unrelated to allele frequency in the monomorphic non-classical MHC-I alleles. Going beyond previous studies, we offer a fine-scale view of selection on classical MHC-I genes in a wild population by revealing differences in the strength of PMBS according to allele frequency and expression level.

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author
; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
adaptive immunity, immune genes, major histocompatibility complex, pathogen-mediated selection, pathogens
in
Proceedings of the Royal Society B: Biological Sciences
volume
291
issue
2017
article number
20232857
pages
11 pages
publisher
Royal Society Publishing
external identifiers
  • pmid:38378156
  • scopus:85185702690
ISSN
0962-8452
DOI
10.1098/rspb.2023.2857
language
English
LU publication?
yes
id
9ef17ea9-ac68-4191-b1aa-729b277a383f
date added to LUP
2024-03-27 09:38:39
date last changed
2024-04-24 13:28:45
@article{9ef17ea9-ac68-4191-b1aa-729b277a383f,
  abstract     = {{<p>The exceptional polymorphism observed within genes of the major histocompatibility complex (MHC), a core component of the vertebrate immune system, has long fascinated biologists. The highly polymorphic classical MHC class-I (MHC-I) genes are maintained by pathogen-mediated balancing selection (PMBS), as shown by many sites subject to positive selection, while the more monomorphic non-classical MHC-I genes show signatures of purifying selection. In line with PMBS, at any point in time, rare classical MHC alleles are more likely than common classical MHC alleles to confer a selective advantage in host–pathogen interactions. Combining genomic and expression data from the blood of wild house sparrows Passer domesticus, we found that only rare classical MHC-I alleles were highly expressed, while common classical MHC-I alleles were lowly expressed or not expressed. Moreover, highly expressed rare classical MHC-I alleles had more positively selected sites, indicating exposure to stronger PMBS, compared with lowly expressed classical alleles. As predicted, the level of expression was unrelated to allele frequency in the monomorphic non-classical MHC-I alleles. Going beyond previous studies, we offer a fine-scale view of selection on classical MHC-I genes in a wild population by revealing differences in the strength of PMBS according to allele frequency and expression level.</p>}},
  author       = {{Watson, Hannah and Drews, Anna and Skogsmyr, Kelly Hultman and Neto, Júlio Manuel and Roved, Jacob and Westerdahl, Helena}},
  issn         = {{0962-8452}},
  keywords     = {{adaptive immunity; immune genes; major histocompatibility complex; pathogen-mediated selection; pathogens}},
  language     = {{eng}},
  month        = {{02}},
  number       = {{2017}},
  publisher    = {{Royal Society Publishing}},
  series       = {{Proceedings of the Royal Society B: Biological Sciences}},
  title        = {{Only rare classical MHC-I alleles are highly expressed in the European house sparrow}},
  url          = {{http://dx.doi.org/10.1098/rspb.2023.2857}},
  doi          = {{10.1098/rspb.2023.2857}},
  volume       = {{291}},
  year         = {{2024}},
}