Summary Natural killer (NK) cells are lymphocytes having vital functions in innate and adaptive immunity, as well as placental reproduction. Controlling education and functional activity of human NK cells are various receptors that recognize HLA class I on the surface of tissue cells. Epitopes of polymorphic HLA-A,-B and –C are recognized by equally diverse killer cell immunoglobulin-like receptors (KIR). In addition, a peptide cleaved from the leader sequence of HLA-A,-B or –C must bind to HLA-E for it to become a ligand for the conserved CD94:NKG2A receptor. Methionine/threonine dimorphism at position -21 of the leader sequence divides HLA-B allotypes into a majority having -21T that do not supply HLA-E binding peptides and a minority having -21M, that do. Genetic analysis of human populations worldwide shows how haplotypes with -21M HLA-B rarely encode the KIR ligands: Bw4+HLA-B and C2+HLA-C KIR. Thus there are two fundamental forms of HLA haplotype: one preferentially supplying CD94:NKG2A ligands, the other preferentially supplying KIR ligands. -21 HLA-B dimorphism divides the human population into three groups: M/M, M/T and T/T. Mass cytometry and assays of immune function, shows how M/M and M/T individuals have CD94:NKG2A+ NK cells which are better educated, phenotypically more diverse and functionally more potent than those in T/T individuals. Fundamental new insights are given to genetic control of NK cell immunity and the evolution that has limited the number of NK cell receptor ligands encoded by an HLA haplotype. These finding suggest new ways to dissect the numerous clinical associations with HLA class I.

To further refine and improve biomedical research in rhesus macaques, it is necessary to increase our knowledge concerning both the degree of allelic variation (polymorphism) and diversity (gene copy number variation) in the killer cell immunoglobulin-like receptor (KIR) gene cluster. Pedigreed animals in particular should be studied, as segregation data will provide clues to the linkage of particular KIR genes/alleles segregating on a haplotype and to its gene content as well. A dual strategy allowed us to screen the presence and absence of genes and the corresponding transcripts, as well as to track differences in transcription levels. On the basis of this approach, 14 diverse KIR haplotypes have been described. These haplotypes consist of multiple inhibitory and activating Mamu-KIR genes, and any gene present on one haplotype may be absent on another. This suggests that the cost of accelerated evolution by recombination may be the loss of certain framework genes on a haplotype.

The highly conserved NendoU replicative domain of nidoviruses (arteriviruses, coronaviruses, and roniviruses) belongs to a small protein family whose cellular branch is prototyped by XendoU, a Xenopus laevis endoribonuclease involved in nucleolar RNA processing. Recently, sequence-specific in vitro endoribonuclease activity was demonstrated for the NendoU-containing nonstructural protein (nsp) 15 of several coronaviruses. To investigate the biological role of this novel enzymatic activity, we have characterized a comprehensive set of arterivirus NendoU mutants. Deleting parts of the NendoU domain from nsp11 of equine arteritis virus was lethal. Site-directed mutagenesis of conserved residues exerted pleiotropic effects. In a first-cycle analysis, replacement of two conserved Asp residues in the C-terminal part of NendoU rendered viral RNA synthesis and virus production undetectable. In contrast, mutagenesis of other conserved residues, including two putative catalytic His residues that are absolutely conserved in NendoU and cellular homologs, produced viable mutants displaying reduced plaque sizes (20 to 80% reduction) and reduced yields of infectious progeny of up to 5 log units. A more detailed analysis of these mutants revealed a moderate reduction in RNA synthesis, with subgenomic RNA synthesis consistently being more strongly affected than genome replication. Our data suggest that the arterivirus nsp11 is a multifunctional protein with a key role in viral RNA synthesis and additional functions in the viral life cycle that are as yet poorly defined.Nidoviruses are enveloped, positive-strand RNA viruses that have been grouped together on the basis of similarities in genome organization, the use of similar strategies for nonstructural and structural protein expression, and the presumed common ancestry of key replicative enzymes (2,3,5,12,24). The order Nidovirales currently includes the families Arteriviridae, Coronaviridae, and Roniviridae. Notwithstanding their taxonomic unification, important differences between nidovirus subgroups exist at the levels of genome size, virion architecture, biology of virus-host interactions, and pathogenesis.Nidovirus RNA synthesis in infected cells entails both amplification of the viral genome and the production of an extensive set of subgenomic (sg) mRNAs, presumably each from their specific negative-stranded intermediates (17-19). RNA synthesis is driven by a set of nidovirus enzymes commonly referred to as "replicase," which include several activities that are rare or lacking in other RNA viruses (23). The replicase is expressed from the incoming genome by translation of the large open reading frames (ORFs) 1a and 1b into polyproteins pp1a and pp1ab. The latter polypeptide is a C-terminally extended version of pp1a and is derived from a Ϫ1 ribosomal frameshift from ORF1a into overlapping ORF1b. The core of the nidovirus replicase polyprotein is formed by a conserved array of enzymatic domains consisting of (from N to C terminus) one or more papain-like "accessory protein...

Induction of experimental autoimmune encephalomyelitis (EAE) has been documented in common marmosets using peptide 34-56 from human myelin/oligodendrocyte glycoprotein ) in incomplete Freund's adjuvant (IFA). Here, we report that this EAE model is associated with widespread demyelination of grey and white matter. We performed an in-depth analysis of the specificity, MHC restriction and functions of the activated T cells in the model, which likely cause EAE in an autoantibody-independent manner. T-cell lines isolated from blood and lymphoid organs of animals immunized with MOG 34-56 displayed high production of IL-17A and specific lysis of MOG 34-56 -pulsed EBV B-lymphoblastoid cells as typical hallmarks. Cytotoxicity was directed at the epitope MOG [40][41][42][43][44][45][46][47][48] presented by the non-classical MHC class Ib allele Caja-E, which is orthologue to HLA-E and is expressed in non-inflamed brain. In vivo activated T cells identified by flow cytometry in cultures with MOG 34-56, CD561 T cells also expressed CD27, but CD16, CD45RO, CD28 and CCR7 were absent. These results show that, in the MOG34-56/IFA marmoset EAE model, a Caja-E-restricted population of autoreactive cytotoxic T cells plays a key role in the process of demyelination in the grey and white matter.Key words: Common marmoset . Cytotoxicity . HLA-E . Oligodendrocytes . Natural killer-cytotoxic T lymphocyte (NK-CTL)Supporting Information available online IntroductionMultiple sclerosis (MS) is a chronic inflammatory disease of the human central nervous system (CNS) of unknown aetiology. The pathological hallmark of MS is the lesion. Lesions are regions of usually focal demyelination of variable size localized in the grey and/or white matter of the brain and spinal cord, formed by a combined cellular and humoral autoimmune attack. CNS-targeting autoimmune reactions are thought to be induced as a response to infection (response-to-infection paradigm) [1], although the pathogen(s) that elicit this pathogenic process in MS has not been identified. We have proposed a responseto-damage paradigm for MS, based on the work in a unique nonhuman primate model of MS, experimental autoimmune encephalomyelitis (EAE) in common marmosets (Callithrix jacchus), [2]. The new concept postulates that autoimmunity in MS patients is caused by a genetically predisposed hyper-response to myelin antigens released from damaged white matter due to an unknown antecedent event. We showed that the most important anti-myelin reactivity for the induction of neurological deficit is mediated by antigen-experienced T-cells specific for peptides 34-56 of myelin/oligodendrocyte glycoprotein ) [3].Subsequently it was demonstrated that these cells could be activated in vivo by immunization of marmosets with MOG in incomplete Freund's adjuvant (IFA) [4]. A peptide in IFA emulsion is a more common formulation for the in vivo activation of antigen-experienced T-cells than for autoreactive T-cells as bacterial ligands of innate antigen receptors are usually required. It is no...

NK cells are essential in shaping immune responses and play an important role during pregnancy and in controlling infections. Killer cell immunoglobulin-like receptors (KIRs) educate the NK cell and determine its state of activation. Our goal was to determine how the KIR repertoire of the rhesus macaque (Macaca mulatta) has been shaped during evolution. The presence or absence of 22 KIR gene groups was determined in 378 animals. Some unexpected observations were made in an outbred colony comprising animals of different origins. For instance, the KIR region appears to be highly plastic, and an unprecedented number of genotypes and haplotypes was observed. In contrast to humans, there is no distinction between group A and B haplotypes in the rhesus macaque, suggesting that different selective forces may be operative. Moreover, specific genes appear to be either present or absent in animals of different geographic origins. This extreme plasticity may have been propelled by co-evolution with the rhesus macaque MHC class I region, which shows signatures of expansion. The mosaic-like complexity of KIR genotypes as observed at the population level may represent an effective strategy for surviving epidemic infections. [3] but they are also involved with the vascularisation process during placentation, and thus contribute to reproductive success [4]. The education and activation state of the NK-cell is determined by the interactions of its receptors with their cognate ligands [5]. It is the shift in equilibrium of inhibitory and activating receptor signaling that ultimately leads to NK-cell activation in the form of cytokine production, cytotoxicity, or priming of the adaptive immune system [6].Killer cell immunoglobulin-like receptors (KIRs) may influence this balance through interactions with their ligands, the MHC molecules, which are called human leukocyte antigens 2719(HLA) in humans. Since both the HLA system and the KIR gene complex are characterized by variation in locus content, and segregate independent of each other, the potential array of interactions can vary considerably between individuals. Understanding the evolution and complexity of these receptor systems has broad medical relevance, since particular combinations of KIR and HLA alleles are associated with the outcome of viral infection, relapse of leukemia after transplantation, susceptibility to autoimmune disease, and successful pregnancy [7][8][9][10]. Because of its close evolutionary relationship to humans, and evidenced by similar immunological responses, the rhesus macaque (Macaca mulatta) is an important animal model to study the onset, progression, and outcome of infectious diseases, experimentally induced autoimmunity, and transplantation [11][12][13]. Moreover, certain human pathogens or their simiantrophic family members have adapted to primates as their natural host, and may show a host-specific pathology. Since in an experimental setting the onset of disease or the actual challenge with a pathogen can be controlled, it is possible to stu...