Comprehensive characterization of MHC class II haplotypes in Mauritian cynomolgus macaques

Abstract

There are currently no nonhuman primate models with fully defined major histocompatibility complex (MHC) class II genetics. We recently showed that six common MHC haplotypes account for essentially all MHC diversity in cynomolgus macaques (Macaca fascicularis) from the island of Mauritius. In this study, we employ complementary DNA cloning and sequencing to comprehensively characterize full length MHC class II alleles expressed at the Mafa-DPA, -DPB, -DQA, -DQB, -DRA, and -DRB loci on the six common haplotypes. We describe 34 full-length MHC class II alleles, 12 of which are completely novel. Polymorphism was evident at all six loci including DPA, a locus thought to be monomorphic in rhesus macaques. Similar to other Old World monkeys, Mauritian cynomolgus macaques (MCM) share MHC class II allelic lineages with humans at the DQ and DR loci, but not at the DP loci. Additionally, we identified extensive sharing of MHC class II alleles between MCM and other nonhuman primates. The characterization of these full-length-expressed MHC class II alleles will enable researchers to generate MHC class II transferent cell lines, tetramers, and other molecular reagents that can be used to explore CD4+ T lymphocyte responses in MCM.

Figure 1. MHC class II amino acid alignments in Mauritian cynomolgus macaques

Alignments of predicted amino acid sequences for all of the MHC class II alleles described in Mauritian cynomolgus macaques. Protein domains were predicted based on previously described predictions in other non-human primates. CP: connecting peptide, TM; transmembrane domain, and Cyto: cytoplasmic domain.

Figure 1. MHC class II amino acid alignments in Mauritian cynomolgus macaques

Alignments of predicted amino acid sequences for all of the MHC class II alleles described in Mauritian cynomolgus macaques. Protein domains were predicted based on previously described predictions in other non-human primates. CP: connecting peptide, TM; transmembrane domain, and Cyto: cytoplasmic domain.

Figure 2. MHC class II alleles associated with each haplotype in Mauritian cynomolgus macaques

The alleles found to be associated with the H1 through H6 haplotypes are shown. Haplotypes have been color-coded to correspond to our previously published description of these haplotypes (Wiseman et al. 2007). The relative physical arrangement of loci was predicted from the alignment of MHC class II alleles recently described in rhesus macaques (Daza-Vamenta et al. 2004). The arrangement of the DRB alleles within the larger DRB locus, however, is arbitrary. Loci furthest to the left are predicted to be telomeric and closest to the MHC class I loci, while loci to the right are predicted to be centromeric and furthest from the MHC class I loci.

Figure 3. MHC class II haplotype frequencies in a cohort of 117 feral Mauritian cynomolgus macaques

In our previous study, microsatellites were used to examine the relative frequencies of different MHC haplotypes in a cohort of 117 feral MCM (Wiseman et al. 2007). Here, we re-evaluated the microsatellite data for the frequency of MHC class II haplotypes on the 234 chromosomes of this cohort.

Figure 4. Phylogenetic analysis of MCM and human MHC class II alleles

(a) DPA; (b) DPB; (c) DQA; (d) DQB; (e) DRA; (f) DRB. The haplotypes of MCM alleles are color-coded as in Figure 2. The numbers on the branches represent the percent of bootstrap samples supporting the branch; only values ≥ 50% are shown.