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The killer cell Ig-like receptors (KIR) modulate immune responses through interactions with MHC class I molecules. The KIR region in large cohorts of rhesus and cynomolgus macaque populations were characterized, and the experimental design enabled the definition of a considerable number of alleles (n = 576) and haplotypes, which are highly variable with regard to architecture. Although high levels of polymorphism were recorded, only a few alleles are shared between species and populations. The rapid evolution of allelic polymorphism, accumulated by point mutations, was further confirmed by the emergence of a novel KIR allele in a rhesus macaque family. In addition to allelic variation, abundant orthologous and species-specific KIR genes were identified, the latter of which are frequently generated by fusion events. The concerted action of both genetic mechanisms, in combination with differential selective pressures at the population level, resulted in the unparalleled rapid evolution of the KIR gene region in two closely related macaque species. The variation of the KIR gene repertoire at the species and population level might have an impact on the outcome of preclinical studies with macaque models. [ABSTRACT FROM AUTHOR]

Butyrophilins (BTN), specifically BTN3A, play a central role in the modulation of γδ T cells, which are mainly present in gut and mucosal tissues. BTN3A1 is known, for example, to activate Vγ9Vδ2 T cells by means of a phosphoantigen interaction. In the extended HLA region, three genes are located, designated BTN3A1, BTN3A2 and BTN3A3, which were also defined in rhesus macaques. In contrast to humans, rhesus monkeys have an additional gene, BTN3A3Like, which has the features of a pseudogene. cDNA analysis of 32 Indian rhesus and 16 cynomolgus macaques originating from multiple-generation families revealed that all three genes are oligomorphic, and the deduced amino acids display limited variation. The macaque BTN3A alleles segregated together with MHC alleles, proving their location in the extended (Major Histocompatibility Complex) MHC. BTN3A nearly full-length transcripts of macaques and humans cluster tightly together in the phylogenetic tree, suggesting that the genes represent true orthologs of each other. Despite the limited level of polymorphism, 15 Mamu- and 14 Mafa-BTN3A haplotypes were defined, and, as in humans, all three BTN3A genes are transcribed in PBMCs and colon tissues. In addition to regular full-length transcripts, a high number of various alternative splicing (AS) products were observed for all BTN3A alleles, which may result in different isoforms. The comparable function of certain subsets of γδ T cells in human and non-human primates in concert with high levels of sequence conservation observed for the BTN3A transcripts presents the opportunity to study these not yet well understood molecules in macaques as a model species. [ABSTRACT FROM AUTHOR]