HLA and Killer Cell Immunoglobulin-like Receptors Influence the Natural Course of CMV Infection

Journal of Infectious Diseases, Oct 2014

Background. Natural killer (NK) cells provide a major defense against cytomegalovirus (CMV) infection through the interaction of their surface receptors, including the activating and inhibitory killer immunoglobulin-like receptors (KIRs), and human leukocyte antigens (HLA) class I molecules. This study assessed whether the KIR and HLA repertoire may influence the risk of developing symptomatic or asymptomatic disease after primary CMV infection in the immunocompetent host. Methods. Sixty immunocompetent patients with primary symptomatic CMV infection were genotyped for KIR and their HLA ligands, along with 60 subjects with a previous asymptomatic infection as controls. Results. The frequency of the homozygous A haplotype (only KIR2DS4 as activating KIR) was higher in symptomatic patients than controls (30% vs 12%, respectively; odds ratio [OR] = 3.24; P = .01). By logistic regression, the risk of developing symptomatic disease was associated with the homozygous A haplotype and the HLABw4T allele. Combining the 2 independent variables, we found that 37 out of 60 (62%) symptomatic patients but only 18 out of 60 (30%) of controls possessed the homozygous A haplotype or the HLABw4T allele with a highly significant OR (OR = 3.75, P < .0005). Conclusions. Immunocompetent subjects carrying the homozygous A haplotype or the HLABw4T allele are at higher risk of developing symptomatic disease after primary CMV infection.

A PDF file should load here. If you do not see its contents the file may be temporarily unavailable at the journal website or you do not have a PDF plug-in installed and enabled in your browser.

Alternatively, you can download the file locally and open with any standalone PDF reader:

http://jid.oxfordjournals.org/content/210/7/1083.full.pdf

HLA and Killer Cell Immunoglobulin-like Receptors Influence the Natural Course of CMV Infection

JID HLA and Killer Cell Immunoglobulin-like Receptors Influence the Natural Course of CMV Infection Danilo Di Bona () 1 2 3 4 Valeria Scafidi 0 1 3 Antonella Plaia 1 3 8 Claudia Colomba 1 3 7 Domenico Nuzzo 0 1 3 Cecilia Occhino 1 3 6 Antonino Tuttolomondo 1 3 5 Giovanni Giammanco 1 3 7 Simona De Grazia 1 3 7 Giuseppe Montalto 1 3 5 Giovanni Duro 0 1 3 Marco Cippitelli 1 3 9 Calogero Caruso 1 2 3 4 0 Istituto di Biomedicina ed Immunologia Molecolare, Consiglio Nazionale delle Ricerche 1 KIR , HLA, and CMV Infection 2 Dipartimento di Biopatologia e Biotecnologie Mediche e Forensi, Università di Palermo 3 Received 13 January 2014; accepted 3 April 2014; electronically published 15 April 2014. sionale, Azienda Ospedaliera Universitaria Policlinico “Paolo Giaccone” , Via Del Ve- spro, 129, 90127 Palermo , Italia 4 Unità Operativa di Medicina Trasfusionale, Azienda Ospedaliera Universitaria Policlinico “Paolo Giaccone” Palermo 5 Dipartimento Biomedico di Medicina Interna e Specialistica, Università di Palermo , Palermo 6 Unità Operativa di Malattie Infettive, Ospedali Riuniti Villa Sofia-Cervello 7 Dipartimento di Scienze per la Promozione della Salute e Materno Infantile “G. D'Alessandro”, Università di Palermo 8 Dipartimento di Scienze Matematiche Statistiche e Aziendali, Università di Palermo 9 Department of Molecular Medicine, Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome , Italy Background. Natural killer (NK) cells provide a major defense against cytomegalovirus (CMV) infection through the interaction of their surface receptors, including the activating and inhibitory killer immunoglobulinlike receptors (KIRs), and human leukocyte antigens (HLA) class I molecules. This study assessed whether the KIR and HLA repertoire may influence the risk of developing symptomatic or asymptomatic disease after primary CMV infection in the immunocompetent host. Methods. Sixty immunocompetent patients with primary symptomatic CMV infection were genotyped for KIR and their HLA ligands, along with 60 subjects with a previous asymptomatic infection as controls. Results. The frequency of the homozygous A haplotype (only KIR2DS4 as activating KIR) was higher in symptomatic patients than controls (30% vs 12%, respectively; odds ratio [OR] = 3.24; P = .01). By logistic regression, the risk of developing symptomatic disease was associated with the homozygous A haplotype and the HLABw4T allele. Combining the 2 independent variables, we found that 37 out of 60 (62%) symptomatic patients but only 18 out of 60 (30%) of controls possessed the homozygous A haplotype or the HLABw4T allele with a highly significant OR (OR = 3.75, P < .0005). Conclusions. Immunocompetent subjects carrying the homozygous A haplotype or the HLABw4T allele are at higher risk of developing symptomatic disease after primary CMV infection. - to be asymptomatic in the immunocompetent host, but a minority of subjects (<10%) exhibit symptoms of the infection, such as malaise, fever, sweating, and abnormal liver function [2]. The reason for this different clinical picture is currently unknown. There is increasingly compelling evidence that natural killer (NK) cells play a crucial role in host defense against CMV infection [3, 4]. In humans, a major component of NK cell target recognition depends on the surveillance of human leukocyte antigen (HLA) class I molecules by killer immunoglobulin-like receptors (KIRs), a family of diverse activating or inhibitory receptors that are expressed on the surface of NK cells and T-cell subsets [5]. Different KIRs can transmit inhibitory or activating signals to the cell, and combinations of KIR genes synergize to generate haplotypes with widely differing balance between activating and inhibitory types. Two broad haplotypes of KIR genes have been defined on the basis of gene content. The A haplotype contains a single surface activating KIR gene, KIR2DS4, which is present as a null allele in 80% of cases, and 5 inhibitory KIR genes (KIR2DL1, KIR2DL3, KIR3DL1, KIR3DL2, and KIR3DL3). In contrast, the B haplotype is characterized by variable numbers of activating and inhibitory genes [6]. KIRs bind specifically defined alleles of HLA-C, HLA-B, or HLA-A [5], but, since HLA and KIR map to separate chromosomes, some individuals lack specific KIR-HLA receptor-ligand pairing, leading to functionally null phenotypes. Recent reports have documented a role for activating KIRs in the control of CMV infection after hematopoietic stem cell transplantation [7] or kidney transplantation [8, 9], showing that the CMV reactivation rate in patients homozygous for the KIR A haplotype (virtually without activating KIRs) is higher than in patients with the B haplotype (with a variable number of activating KIRs), suggesting the importance of activating KIRs in the immune surveillance against CMV. Other reports have documented a role for inhibitory KIRs in other infectious diseases [10–13]. In this study, we tested the hypothesis that the KIR and HLA repertoire might influence the appearance of CMV symptomatic infection in the immunocompetent host. METHODS Patients Between November 2011 and May 2013, a total of 60 consecutive patients with symptomatic acute CMV infection were recruited from 2 southern Italian hospitals (University of Palermo Medical Center, and Cervello Hospital, Palermo). Patients were included if they were immunocompetent adult subjects, with positive serological test for acute CMV infection (CMV–immunoglobin M [IgM] positive/CMV–immunoglobin G [IgG] negative test), with at least 1 of the following symptoms: fever, lymphadenopathy, splenomegaly, or clinical manifestations of hepatitis, encephalitis, or pneumonia. Patients were excluded if they had a positive test for surface antigen of the hepatitis B virus (HBsAg), anti–human immunodeficiency virus (anti-HIV), or anti–hepatitis C virus (anti-HCV) antibodies, or if they were being treated with any immunosuppressant drugs. As a control group, 60 blood donors, matched to the study population by age (±2 years) and sex with the study population, with a previous asymptomatic CMV infection (CMVIgM negative/CMV-IgG positive test, without any reported manifestations of acute CMV infection as assessed by interview) were retrospectively enrolled. Informed consent was obtained for collection of samples from all patients and controls. Consent forms were administered by physicians involved in the study. HLA and KIR Genotyping DNA was obtained from peripheral blood leukocytes by the salting-out technique [14]. Using the polymerase chain reaction sequence-specific primer (PCR-SSP) technique, the DNA of cases and controls were genotyped for the presence of the 3 major KIR ligand groups, HLA-C1, HLA-C2, and HLA-Bw4 (Epitop-TYPE kit; BAG Health Care GmbH, Lich, Germany). These were assigned directly by using specific oligonucleotide primers to type the codon corresponding to amino acid 80 for HLA-C (HLA-C1, Cw alleles with asparagine at position 80; HLA-C2, Cw alleles with lysine at position 80) and for HLA-Bw4 (Bw4-I, Bw alleles with isoleucine at position 80; Bw4-T, Bw alleles with threonine at position 80). KIR genotyping was performed for both inhibitory and activating KIR using the KIR-TYPE kit (BAG Health Care GmbH). The following KIR genes were analyzed, which included the inhibitory receptors KIR2DL1, 2DL2, 2DL3, 2DL5, 3DL1, 3DL2, 3DL3, the activating receptors 2DL4, 2DS1, 2DS2, 2DS3, 2DS4, 2DS5, 3DS1, 2 pseudogenes (2DP1 and 3DP1) and the common variants of KIR2DL5 (KIR2DL5A, KIR2DL5B), the KIR2DS4 allele (*001 = 002 and *003), and KIR3DP1 allele (*001 = 002 and *003). KIR gene profiles were determined by the presence or absence of each KIR gene. Statistical Analysis Comparisons of frequencies were made using 2 × 2 contingency tables analyzed by the χ2 test. A logistic regression model was also considered in analyzing the data. The procedure started from a full model, including a set of variables as covariates encompassing all KIR genes and their HLA ligands, together with their interactions reputed as the most important, as suggested by the literature [6]. A backward procedure that compares nested models by Akaike Information Criterion was carried out to obtain the final set of significant covariates reported in Table 2. An analogous procedure was used for the dataset containing only the subjects with the B haplotype, resulting in the subset of significant covariates reported in Table 4. The whole analysis was performed by R (R Core Team, 2013) [15]. The median age of the 60 consecutively enrolled CMV infected patients was 36 years, (ranging from 18 to 65 years), with a prevalence of males (37 out of 60 patients, 62% of cases). By univariate analysis, the frequency of individuals with the A haplotype in homozygosis was higher in the group with symptomatic infection (30%) than in controls (12%) (odds ratio [OR] = 3.24; P = .01), suggesting that subjects without activating receptors (AA haplotype) are more susceptible to Table 1. Frequencies of KIR, HLA, and KIR-HLA Combinations Among Individuals With Symptomatic and Asymptomatic CMV Infection Frequency Symptomatic Infection N = 60 N (%) Genetic Factor Haplotype AA Haplotype AB + BB KIR2DS2 was the only KIR gene reported in the table because it was the only one differently expressed between cases and controls. The KIR-HLA interaction suggested by literature were analyzed and reported in the table. Abbreviations: CMV, cytomegalovirus; HLA, human leukocyte antigen; KIR, killer immunoglobulin-like receptor; OR, odds ratio. a Statistical significance (P < .05). b Marginal statistical significance (P < .1). develop symptomatic infection (Table 1). The frequency of only 1 out of the 19 KIR genes analyzed, the activating KIR2DS2 gene, was significantly different in the 2 groups, being less frequent in the subjects with symptomatic infection (27%) than in controls (45%) (OR = 0.44; P = .03), again supporting a role of activating genes in the control of infection (Table 1). The frequency of the HLA-C1 alleles was not different in the groups, but its interaction with the activating receptor KIR2DS2 Table 2. Logistic Regression Model to Predict the Occurrence of Symptomatic Infection in All Subjects (n = 120) OR (95% CI) HLA-Bw4T 0: Absent 1.64 0.56 .003 5.14 (1.84–16.27) 5.03 (1.60–17.96) 2.34 (.68–8.87) 4.54 (1.14–20.11) 0.96 0.47 .04 2.62 (1.06–6.72) Sex and age did not enter into the final model after the stepwise procedure. Abbreviations: CI, confidence interval; HLA, human leukocyte antigen; n.s., not significant; OR, odds ratio; SE, standard error. (KIR2DS2-HLA-C1) was less frequent in the patients (7%) than in controls (22%) (OR = 0.26; P = .02) (Table 1). The frequency of subjects with 2 copies of HLA-C2 alleles (HLAC2C2) was higher in the patients (52%) than in controls (32%) (OR = 2.31; P = .03) (Table 1). Finally, the frequency of HLA-Bw4T alleles was higher in patients (35%) than in controls (20%) (OR = 2.15) at marginal statistical significance (P = .06) (Table 1). No difference was observed in the number of activating receptors between patients and controls (data not shown). Multiple logistic regression analysis considering variables that were both significant (P < .05) and not significant (P ≥ .05) in univariate analysis confirmed that AA haplotype (OR = 5.14; P = .003), HLA-C2C2 (OR = 5.03; P = .008), and also HLA-C1C1 (OR = 4.54; P = .04) were more frequent in patients with acute symptomatic CMV infection (Table 2) than in controls, whereas KIR2DS2 either alone or in combination with HLA-C1 was no longer associated with the outcome of infection. Notably, the HLA-Bw4T, which was only marginally statistically significant in the univariate analysis, was found to be a predictor of the risk of symptomatic infection by multivariate analysis (OR = 2.62; P = .04), suggesting an interaction with other significant variables, such as the haplotype. To assess if there were differences between patients and controls possessing the BB/BA haplotype (Bx haplotype), we analyzed the data of this subgroup of subjects separately, excluding the subjects with the AA haplotype, which was shown to be detrimental by itself. Using univariate analysis limited to the Bx haplotype subjects of both groups, the frequency of HLABw4T alleles was found to be different in the groups both in Table 3. Frequencies of HLA and KIR-HLA Combinations Among AB/BB Haplotype Individuals With Symptomatic and Asymptomatic CMV Infection Frequency Symptomatic Infection N = 42 N (%) Genetic Factor The KIR-HLA interaction suggested by literature were analyzed and reported in the table. Abbreviations: CMV, cytomegalovirus; HLA, human leukocyte antigen; KIR, killer immunoglobulin-like receptor; OR, odds ratio. a Statistical significance (P < .05). b Marginal statistical significance (P < .1). heterozygosis ( patients [45%] and controls [21%] [OR = 3.15; P = .01]) and in homozygosis ( patients [36%], controls [17%] [OR = 2.72; P = .03]) (Table 3). Moreover, the interaction of HLA-Bw4T with the inhibitory receptor KIR3DL1 (KIR3DL1HLA-Bw4T) was more frequent in patients (40%) than in controls (19%) (OR = 2.92; P = .02) (Table 3). This difference was mainly due to HLA-Bw4T homozygous subjects [(KIR3DL1HLA-Bw4TT: patients (33%), controls (15%) (OR = 2.81, P = .03)] (Table 3). These data suggest that the interaction of HLA-Bw4T with the inhibitory receptor KIR3DL1 may counteract the activating receptors of the B haplotype in the symptomatic patients. Moreover, the frequency of subjects with 2 Table 4. Logistic Regression Model to Predict the Occurrence of Symptomatic Infection in AB/BB Haplotype Subjects (n = 95) OR (95% CI) HLA-Bw4I 0: Absent 2.79 (1.13–7.16) 0.40 (.10–1.30) Sex and age did not enter into the final model after the stepwise procedure. Abbreviations: CI, confidence interval; HLA, human leukocyte antigen; n.s., not significant; OR, odds ratio; SE, standard error. copies of HLA-C2 alleles (HLA-C2C2) was higher in the patients (55%) than in controls (34%) (OR = 2.35; P = .04) (Table 3). The multiple logistic regression analysis considering variables that were both significant (P < .05) and not significant (P ≥ .05) in the univariate analysis confirmed only the detrimental effect of HLA-Bw4T (OR = 2.79, 95% confidence interval [CI], 1.13, 7.16; P = .03), while the interactions KIR3DL1-HLABw4T, and HLA-C2C2 were no longer significant (actually, if the interaction KIR3DL1-HLA-Bw4T is introduced in the model without including HLA-Bw4T alone, it is significant: OR = 2.92, 95% CI, 1.18, 7.58; P = .02). Sex and age, analyzed as conditioning variables, did not show any statistically significant difference between the groups both in the overall (Table 2) and the B haplotype subgroup multiple variable logistic regression analysis (Table 4). Finally, 37 out of 60 (62%) symptomatic patients but only 18 out of 60 (30%) controls possessed the A haplotype or the HLABw4T (the independent variable predicting symptomatic CMV disease that was statistically significant in both logistic regression models) with a highly significant OR (OR 3.75; P < .0005). DISCUSSION This genetic association study shows that immunocompetent adult subjects possessing the KIR AA haplotype or the HLABw4T allele are more susceptible to develop a symptomatic acute disease after primary CMV infection. The reported association between the homozygous A haplotype and the risk of acute symptomatic disease is consistent with findings of other studies in which immunosuppressed subjects carrying the AA haplotype were shown to have a higher rate of CMV reactivation in the setting of bone marrow transplantation [7] or kidney transplantation [8]. In another study, it was also shown that in subjects who underwent kidney transplantation, the rate of CMV reactivation was inversely correlated with the number of activating KIRs [9], further supporting the role of activating KIRs in the control of CMV infection. Our study extends these findings showing that in the immunocompetent host as well the activating KIRs also have a protective role against CMV infection. This protection was independent of the absolute number of activating KIR genes, because no difference was reported between patients and controls. Furthermore, this study suggests that the presence of the HLA-Bw4T allele may influence the outcome of the disease. This effect could possibly be mediated by an interaction of HLA-Bw4T with the inhibitory KIR3DL1, and was almost exclusively observed in the Bx haplotype subjects. This may suggest that there is less protection by the B haplotype due to this inhibitory interaction in the subgroup of Bx haplotype symptomatic patients carrying the KIR3DL1-HLABw4T combined genotype. The KIR3DL1HLABw4T inhibitory association has never been observed before for CMV infection. A single case report suggested a possible detrimental effect on CMV disease by another inhibitory receptor, showing that the abnormal expression of KIR2DL1 in the entire NK cell population of a young patient (with a genetic defect) was associated with severe recurrent CMV symptomatic disease [4]. In our cohort of patients, the supposed inhibitory receptor-ligand interaction KIR3DL1-HLABw4T is solely related to the different frequency of the HLABw4T gene, because the KIR3DL1 gene is equally represented, at high frequency, in both patients and controls (in 56 out of 60 subjects in each group). This effect seems to be “gene doseindependent,” because it was observed both in the HLABw4T heterozygous and homozygous subjects, which are the vast majority in this cohort of patients. In contrast to the KIR3DL1-HLA-Bw4T interaction, we did not observe an association between the KIR3DL1 and the HLA-Bw4I allele, which is generally considered a better ligand than HLA-Bw4T for most KIR3DL1 allotypes [16–18]. This lack of association could suggest that the KIR3DL1 would not be involved in the detrimental effect of the HLA-Bw4T, whose mechanism of action would thus remain unexplained. But direct and indirect data suggest that some HLA-Bw4T allotypes are better ligands for certain KIR3DL1 subtypes [12, 19], consistent with the functional role of the KIR3DL1-HLABw4T interaction reported here, depending on which subtypes are involved. We did not analyze the different KIR and HLA subtypes in this set of data, but this issue will be explored in the future. Alternatively, it should be considered that, as reported in several studies, HLABw4I also binds the activating KIR3DS1 [11, 20, 21], which has recently been implicated in protection against CMV [22, 23]; this interaction could offset the inhibitory activity mediated by the interaction with KIR3DL1. In contrast, the HLABw4T allele does not bind the activating KIR3DS1, but only the inhibiting KIR3DL1, leading to a prevalent transmission of inhibitory signals to the cells (compared to the HLABw4I allele). The HLABw4 and the KIR3DL1 and KIR3DS1 loci have previously been implicated in conditioning HIV disease outcome, although data from different studies are inconsistent [11–13]. Surprisingly, individuals possessing the highly inhibitory KIR3DL1 allele, along with their HLABw4 ligands, were relatively more protected against HIV infection [12]. Another different inhibitory KIR-HLA association, KIR2DL3-HLAC1, was shown to be associated with spontaneous resolution of HCV infection [10]. The authors hypothesized that the reported association would be protective because it is more easily overridden by activating signals compared with other stronger inhibitory interactions, such as KIR2DL2-HLAC1 or KIR2DL1-HLAC2 [10]. This mechanism is different from what is proposed in our study, which is related to a stronger inhibitory signal transmitted by the KIR3DL1-HLABw4T interaction, capable of overcoming activating signals. It is worth noting that the patients with the AA haplotype or Bx haplotype and HLABw4T are twice as numerous as controls (37 vs 18, respectively) with a highly significant OR (OR 3.75; P < .0005). This suggests that primary symptomatic CMVinfected patients represent a specific subgroup in terms of KIR-HLA genes. This observation strengthens the role of NK cells for a rapid and effective immune response to human CMV infection. Although functional data have mainly implicated the NKG2/HLA-E system in the control of CMV infection [24, 25], our genetic data highlight the importance of both activating and inhibitory KIR interactions with polymorphic HLA molecules in human CMV infection, not only in immunecompromised patients, as shown by recent evidence [7–9], but also in the immunocompetent host. Two-thirds of the patients consecutively enrolled in the study were males. However, we did not observe differences in genotype distribution with this set of data when subjects were categorized according to gender, indicating that KIRs may not be involved in the different prevalence of the symptomatic infection between males and females. Similarly, we did not observe any difference in genotype distribution between patients categorized according to age. A limit of this analysis is the relatively small sample size. This could have reduced the statistical power and limited the ability to identify some KIR-HLA interactions that may not achieve statistical significance even with a very different OR between the groups in some comparisons. An example is represented by the activating KIR2DS2HLAC1 interaction, which was significantly less frequent in patients than controls in the univariate analysis shown in Table 1. We observed that 3 out of 4 KIR2DS2-HLAC1 interactions among patients and 12 out of 13 among controls occur in those subjects with the Bx haplotype and without the abovereported inhibitory interaction KIR3DL1-HLABw4T (3/23 [13%] in patients, 12/42 [29%], in controls; OR = 0.38). The KIR2DS2-HLAC1 interaction is consistent with our model, indicating another difference in the B haplotype subpopulation among patients and controls, possibly leading to a stronger response in controls, even though not statistically significant. Another limitation related to the relatively small sample size was that we could not analyze any possible interactions between KIR and HLA, so we limited our analysis only to the supposed interactions suggested by literature data. This hampered the opportunity to identify possible novel interactions. An analysis aiming to find a possible correlation between the KIR or HLA genotype and the outcome of CMV infection in symptomatic patients has also been performed. Regarding the clinical presentation, most of the patients have malaise, fever, and lymphatic node swelling with or without mild hepatitis, some patients had more severe hepatitis, 3 patients had pneumonia, and 1 patient had severe neuropathy. Given the heterogeneity of clinical presentation, to improve the sensitivity of the statistical analysis, we tried to categorize patients according to the severity of disease, grouping them in classes according to a specific sign or symptom (eg, level of alanine aminotransferase; number of lymphocytes; or severity of clinical presentation, such as severe hepatitis or pneumonia, etc.). In this analysis, we did not find any association between the outcome of symptomatic infection and a particular genetic signature (HLA, KIR haplotype or specific KIR gene). However, it is possible that the small sample size (60 patients) could have limited the reliability of the analysis (data not shown). In conclusion, studying a cohort of 120 subjects with CMV infection, we provide evidence for a detrimental effect of the AA haplotype or the HLA-Bw4T allele on the outcome of primary CMV disease, suggesting that KIR and HLA polymorphisms play a primary role in the immunocompetent host. The data suggest that HLABw4T alleles likely exert their function through their association with the inhibitory KIR3DL1, but the exact mechanism remains to be explained. The results provided here show that genetic differences are present between subjects with different abilities to respond to primary CMV infection, suggesting that a specific KIR and HLA gene segregation was likely the result of a selective pressure by CMV. Characterization of NK cell population/phenotype, together with co-culture experiments with CMV infected cells (eg, CMV-infected fibroblast cells) and patient or donor NK cells, will be conducted in further investigations to assess whether a differential phenotype/maturation of NK cells could depend on the expression of different KIR/HLA genotypes or haplotypes. Considering the profound effects of CMV infection on the health and quality of life of immunocompromised individuals [26], patients with comorbidities, the elderly, and children, and also its importance in immunosenescence [27], identifying the mechanisms responsible for the genetic control of CMV may provide important insight into the functioning of NK cells in the context of the infection and may have important clinical implications. Notes Financial support. This work was supported by Project University of Palermo (UNIPA) “Fondi Finalizzati alla Ricerca” (FFR) 2012-ATE-03409. Potential conflicts of interest. All authors: No reported conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed. 1. Cannon MJ , Schmid DS , Hyde TB . Review of cytomegalovirus seroprevalence and demographic characteristics associated with infection . Rev Med Virol 2010 ; 20 : 202 - 13 . 2. Eddleston M , Peacock S , Juniper M , Warrell DA . Severe cytomegalovirus infection in immunocompetent patients . Clin Infect Dis 1997 ; 24 : 52 - 6 . 3. Biron CA , Byron KS , Sullivan JL . Severe herpesvirus infections in an adolescent without natural killer cells . N Engl J Med 1989 ; 320 : 1731 - 5 . 4. Gazit R , Garty BZ , Monselise Y , et al. Expression of KIR2DL1 on the entire NK cell population: a possible novel immunodeficiency syndrome . Blood 2004 ; 103 : 1965 - 6 . 5. Lanier LL . NK cell recognition . Annu Rev Immunol 2005 ; 23 : 225 - 74 . 6. Kulkarni S , Martin MP , Carrington M. The Yin and Yang of HLA and KIR in human disease . Semin Immunol 2008 ; 20 : 343 - 52 . 7. Cook M , Briggs D , Craddock C , et al. Donor KIR genotype has a major influence on the rate of cytomegalovirus reactivation following T-cell replete stem cell transplantation . Blood 2006 ; 107 : 1230 - 2 . 8. Hadaya K , de Rham C , Bandelier C , et al. Natural killer cell receptor repertoire and their ligands, and the risk of CMV infection after kidney transplantation . Am J Transplant 2008 ; 8 : 2674 - 83 . 9. Stern M , Elsässer H , Hönger G , Steiger J , Schaub S , Hess C. The number of activating KIR genes inversely correlates with the rate of CMV infection/reactivation in kidney transplant recipients . Am J Transplant 2008 ; 8 : 1312 - 7 . 10. Khakoo SI , Thio CL , Martin MP , et al. HLA and NK cell inhibitory receptor genes in resolving hepatitis C virus infection . Science 2004 ; 305 : 872 - 4 . 11. Martin MP , Gao X , Lee JH , et al. Epistatic interaction between KIR3DS1 and HLA-B delays the progression to AIDS . Nat Genet 2002 ; 31 : 429 - 34 . 12. Martin MP , Qi Y , Gao X , et al. Innate partnership of HLA-B and KIR3DL1 subtypes against HIV-1 . Nat Genet 2007 ; 39 : 733 - 40 . 13. Gaudieri S , DeSantis D , McKinnon E , et al. Killer immunoglobulin-like receptors and HLA act both independently and synergistically to modify HIV disease progression . Genes Immun 2005 ; 6 : 683 - 90 . 14. Miller SA , Dykes DD , Polesky HF . A simple salting out procedure for extracting DNA from human nucleated cells . Nucleic Acid Res 1998 ; 16 : 1215 . 15. R Development Core Team . R: A language and environment for statistical computing . Vienna, Austria: R Foundation for Statistical Computing, 2009 . ISBN 3- 900051 - 07 -0. http://www.R-project.org. Accessed 15 November 2013 . 16. Carr WH , Pando MJ , Parham P. KIR3DL1 polymorphisms that affect NK cell inhibition by HLA-Bw4 ligand . J Immunol 2005 ; 175 : 5222 - 9 . 17. Cella M , Longo A , Ferrara GB , Strominger JL , Colonna M. NK3-specific natural killer cells are selectively inhibited by Bw4-positive HLA alleles with isoleucine 80 . J Exp Med 1994 ; 180 : 1235 - 42 . 18. Gumperz JE , Barber LD , Valiante NM , et al. Conserved and variable residues within the Bw4 motif of HLA-B make separable contributions to recognition by the NKB1 killer cell-inhibitory receptor . J Immunol 1997 ; 158 : 5237 - 41 . 19. Luque I , Solana R , Galiani MD , et al. Threonine 80 on HLA-B27 confers protection against lysis by a group of natural killer clones . Eur J Immunol 1996 ; 26 : 1974 - 7 . 20. Qi Y , Martin MP , Gao X , et al. KIR/ HLA pleiotropism: protection against both HIV and opportunistic infections . PLOS Pathog 2006 ; 2 : e79 . 21. Alter G , Martin MP , Teigen N , et al. Differential natural killer cellmediated inhibition of HIV-1 replication based on distinct KIR/HLA subtypes . J Exp Med 2007 ; 204 : 3027 - 36 . 22. Charoudeh HN , Terszowski G , Czaja K , Gonzalez A , Schmitter K , Stern M. Modulation of the natural killer cell KIR repertoire by cytomegalovirus infection . Eur J Immunol 2013 ; 43 : 480 - 7 . 23. Stern M , Hadaya K , Hönger G , et al. Telomeric rather than centromeric activating KIR genes protect from cytomegalovirus infection after kidney transplantation . Am J Transplant 2011 ; 11 : 1302 - 7 . 24. Tomasec P , Braud VM , Rickards C , et al. Surface expression of HLA-E, an inhibitor of natural killer cells, enhanced by human cytomegalovirus gpUL40 . Science 2000 ; 287 : 1031 . 25. Ulbrecht M , Martinozzi S , Grzeschik M , et al. Cutting edge: the human cytomegalovirus UL40 gene product contains a ligand for HLA-E and prevents NK cell-mediated lysis . J Immunol 2000 ; 164 : 5019 - 22 . 26. Lindholm PF , Annen K , Ramsey G . Approaches to minimize infection risk in blood banking and transfusion practice . Infect Disord Drug Targets 2011 ; 11 : 45 - 56 . 27. Pawelec G , Akbar A , Caruso C , Solana R , Grubeck-Loebenstein B , Wikby A. Human immunosenescence: is it infectious? Immunol Rev 2005 ; 205 : 257 - 68 .


This is a preview of a remote PDF: http://jid.oxfordjournals.org/content/210/7/1083.full.pdf

Danilo Di Bona, Valeria Scafidi, Antonella Plaia, Claudia Colomba, Domenico Nuzzo, Cecilia Occhino, Antonino Tuttolomondo, Giovanni Giammanco, Simona De Grazia, Giuseppe Montalto, Giovanni Duro, Marco Cippitelli, Calogero Caruso. HLA and Killer Cell Immunoglobulin-like Receptors Influence the Natural Course of CMV Infection, Journal of Infectious Diseases, 2014, 1083-1089, DOI: 10.1093/infdis/jiu226