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The major histocompatibility complex in Old World camelids and low polymorphism of its class II genes

BACKGROUND: The Major Histocompatibility Complex (MHC) is a genomic region containing genes with crucial roles in immune responses. MHC class I and class II genes encode antigen-presenting molecules expressed on the cell surface. To counteract the high variability of pathogens, the MHC evolved into...

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Autores principales: Plasil, Martin, Mohandesan, Elmira, Fitak, Robert R., Musilova, Petra, Kubickova, Svatava, Burger, Pamela A., Horin, Petr
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4774177/
https://www.ncbi.nlm.nih.gov/pubmed/26931144
http://dx.doi.org/10.1186/s12864-016-2500-1
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author Plasil, Martin
Mohandesan, Elmira
Fitak, Robert R.
Musilova, Petra
Kubickova, Svatava
Burger, Pamela A.
Horin, Petr
author_facet Plasil, Martin
Mohandesan, Elmira
Fitak, Robert R.
Musilova, Petra
Kubickova, Svatava
Burger, Pamela A.
Horin, Petr
author_sort Plasil, Martin
collection PubMed
description BACKGROUND: The Major Histocompatibility Complex (MHC) is a genomic region containing genes with crucial roles in immune responses. MHC class I and class II genes encode antigen-presenting molecules expressed on the cell surface. To counteract the high variability of pathogens, the MHC evolved into a region of considerable heterogeneity in its organization, number and extent of polymorphism. Studies of MHCs in different model species contribute to our understanding of mechanisms of immunity, diseases and their evolution. Camels are economically important domestic animals and interesting biomodels. Three species of Old World camels have been recognized: the dromedary (Camelus dromedarius), Bactrian camel (Camelus bactrianus) and the wild camel (Camelus ferus). Despite their importance, little is known about the MHC genomic region, its organization and diversity in camels. The objectives of this study were to identify, map and characterize the MHC region of Old World camelids, with special attention to genetic variation at selected class MHC II loci. RESULTS: Physical mapping located the MHC region to the chromosome 20 in Camelus dromedarius. Cytogenetic and comparative analyses of whole genome sequences showed that the order of the three major sub-regions is “Centromere - Class II – Class III – Class I”. DRA, DRB, DQA and DQB exon 2 sequences encoding the antigen binding site of the corresponding class II antigen presenting molecules showed high degree of sequence similarity and extensive allele sharing across the three species. Unexpectedly low extent of polymorphism with low numbers of alleles and haplotypes was observed in all species, despite different geographic origins of the camels analyzed. The DRA locus was found to be polymorphic, with three alleles shared by all three species. DRA and DQA sequences retrieved from ancient DNA samples of Camelus dromedarius suggested that additional polymorphism might exist. CONCLUSIONS: This study provided evidence that camels possess an MHC comparable to other mammalian species in terms of its genomic localization, organization and sequence similarity. We described ancient variation at the DRA locus, monomorphic in most species. The extent of molecular diversity of MHC class II genes seems to be substantially lower in Old World camels than in other mammalian species. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12864-016-2500-1) contains supplementary material, which is available to authorized users.
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spelling pubmed-47741772016-03-03 The major histocompatibility complex in Old World camelids and low polymorphism of its class II genes Plasil, Martin Mohandesan, Elmira Fitak, Robert R. Musilova, Petra Kubickova, Svatava Burger, Pamela A. Horin, Petr BMC Genomics Research Article BACKGROUND: The Major Histocompatibility Complex (MHC) is a genomic region containing genes with crucial roles in immune responses. MHC class I and class II genes encode antigen-presenting molecules expressed on the cell surface. To counteract the high variability of pathogens, the MHC evolved into a region of considerable heterogeneity in its organization, number and extent of polymorphism. Studies of MHCs in different model species contribute to our understanding of mechanisms of immunity, diseases and their evolution. Camels are economically important domestic animals and interesting biomodels. Three species of Old World camels have been recognized: the dromedary (Camelus dromedarius), Bactrian camel (Camelus bactrianus) and the wild camel (Camelus ferus). Despite their importance, little is known about the MHC genomic region, its organization and diversity in camels. The objectives of this study were to identify, map and characterize the MHC region of Old World camelids, with special attention to genetic variation at selected class MHC II loci. RESULTS: Physical mapping located the MHC region to the chromosome 20 in Camelus dromedarius. Cytogenetic and comparative analyses of whole genome sequences showed that the order of the three major sub-regions is “Centromere - Class II – Class III – Class I”. DRA, DRB, DQA and DQB exon 2 sequences encoding the antigen binding site of the corresponding class II antigen presenting molecules showed high degree of sequence similarity and extensive allele sharing across the three species. Unexpectedly low extent of polymorphism with low numbers of alleles and haplotypes was observed in all species, despite different geographic origins of the camels analyzed. The DRA locus was found to be polymorphic, with three alleles shared by all three species. DRA and DQA sequences retrieved from ancient DNA samples of Camelus dromedarius suggested that additional polymorphism might exist. CONCLUSIONS: This study provided evidence that camels possess an MHC comparable to other mammalian species in terms of its genomic localization, organization and sequence similarity. We described ancient variation at the DRA locus, monomorphic in most species. The extent of molecular diversity of MHC class II genes seems to be substantially lower in Old World camels than in other mammalian species. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12864-016-2500-1) contains supplementary material, which is available to authorized users. BioMed Central 2016-03-01 /pmc/articles/PMC4774177/ /pubmed/26931144 http://dx.doi.org/10.1186/s12864-016-2500-1 Text en © Plasil et al. 2016 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research Article
Plasil, Martin
Mohandesan, Elmira
Fitak, Robert R.
Musilova, Petra
Kubickova, Svatava
Burger, Pamela A.
Horin, Petr
The major histocompatibility complex in Old World camelids and low polymorphism of its class II genes
title The major histocompatibility complex in Old World camelids and low polymorphism of its class II genes
title_full The major histocompatibility complex in Old World camelids and low polymorphism of its class II genes
title_fullStr The major histocompatibility complex in Old World camelids and low polymorphism of its class II genes
title_full_unstemmed The major histocompatibility complex in Old World camelids and low polymorphism of its class II genes
title_short The major histocompatibility complex in Old World camelids and low polymorphism of its class II genes
title_sort major histocompatibility complex in old world camelids and low polymorphism of its class ii genes
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4774177/
https://www.ncbi.nlm.nih.gov/pubmed/26931144
http://dx.doi.org/10.1186/s12864-016-2500-1
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