Role of IL-27 in Epstein-Barr virus infection revealed by IL-27RA deficiency.

Epstein-Barr virus (EBV) infection can engender severe B cell lymphoproliferative diseases1,2. The primary infection is often asymptomatic or causes infectious mononucleosis (IM), a self-limiting lymphoproliferative disorder3. Selective vulnerability to EBV has been reported in association with inherited mutations impairing T cell immunity to EBV4. Here we report biallelic loss-of-function variants in IL27RA that underlie an acute and severe primary EBV infection with a nevertheless favourable outcome requiring a minimal treatment. One mutant allele (rs201107107) was enriched in the Finnish population (minor allele frequency = 0.0068) and carried a high risk of severe infectious mononucleosis when homozygous. IL27RA encodes the IL-27 receptor alpha subunit5,6. In the absence of IL-27RA, phosphorylation of STAT1 and STAT3 by IL-27 is abolished in T cells. In in vitro studies, IL-27 exerts a synergistic effect on T-cell-receptor-dependent T cell proliferation7 that is deficient in cells from the patients, leading to impaired expansion of potent anti-EBV effector cytotoxic CD8+ T cells. IL-27 is produced by EBV-infected B lymphocytes and an IL-27RA-IL-27 autocrine loop is required for the maintenance of EBV-transformed B cells. This potentially explains the eventual favourable outcome of the EBV-induced viral disease in patients with IL-27RA deficiency. Furthermore, we identified neutralizing anti-IL-27 autoantibodies in most individuals who developed sporadic infectious mononucleosis and chronic EBV infection. These results demonstrate the critical role of IL-27RA-IL-27 in immunity to EBV, but also the hijacking of this defence by EBV to promote the expansion of infected transformed B cells.

Causal association between inflammatory bowel disease and herpes virus infections: a two-sample bidirectional Mendelian randomization study.

Background: Previous observational or retrospective studies have suggested an association between inflammatory bowel disease (IBD) and herpes virus infections. Using Mendelian randomization (MR) approach, our objective was to determine whether there was a causal association between IBD and herpes virus infections. Methods: In genome-wide association study (GWAS) datasets of the International Inflammatory Bowel Disease Genetics Consortium, we obtained genetic instrumental variables for three phenotypes from 34,652 participants (12,882 IBD cases and 21,770 controls), 27,432 participants [6,968 ulcerative colitis (UC) cases and 20,464 controls], and 20,883 participants [5,956 Crohn's disease (CD) cases and 14,927 controls], respectively. Summary statistics for herpes virus infections (chickenpox, herpes zoster, and mononucleosis) were obtained from the FinnGen database. MR results were expressed as odds ratio (OR) with 95% confidence interval (CI). Results: Our study found no evidence of a causal effect of genetically predicted IBD on herpes virus infections [P value for inverse variance weighting (IVW): 0.063 to 0.652]. For the subtypes of IBD, UC had a suggestive association with mononucleosis (P value for IVW: 0.023). It appeared that CD was also weakly associated with mononucleosis (P value for IVW: 0.058; P value for Weighted median: 0.036). In addition, we found a suggestive causality for CD on chickenpox (P value for IVW: 0.038). Neither UC (P value for IVW: 0.574) nor CD (P value for IVW: 0.168) has a causal effect on herpes zoster. The results of the bidirectional MR analysis did not indicate that herpes virus infections were associated with IBD, UC or CD (P value for IVW: 0.239 to 0.888). Conclusion: This study showed a suggestive causality for both CD-chickenpox and UC-mononucleosis, despite no associations reaching a statistical significance value after corrections for multiple testing. There was no evidence of a causal association between IBD and its two subtypes on herpes zoster.

A gene expression signature that correlates with CD8+T cell expansion in acute Epstein-Barr virus infection.

Acute infectious mononucleosis (AIM) is associated with Epstein-Barr virus (EBV) infection. We explored molecular mechanisms regarding the expression of CD8+T cells in convalescence stage (CONV). Differentially expressed genes (DEGs) were identified by analyzing GEO expression profiles. Subsequently, Gene Set Enrichment Analysis (GSEA), Protein-Protein Interactions (PPI) network, and gene-micro RNAs networks were used to identify hub genes and associated pathways. GSEA provided evidence that the top 3 gene sets in GSEA were all related to integrins. We identified ten hub genes in the PPI network and DGIdb was applied to predict potential targets that might reverse the expression of hub genes. Our study enhances a mechanistic understanding of the CD8+T cells expansion in acute EBV infection and provides potential treatment targets for further research. Keywords: acute infectious mononucleosis; bioinformatics; CD8+T cells; differentially expressed genes; EBV.

TLR4 896A/G and TLR9 1174G/A polymorphisms are associated with the risk of infectious mononucleosis.

Toll-like receptors (TLRs) recognize pathogen-associated molecular patterns and activate innate and adaptive immune responses. Single nucleotide polymorphisms (SNPs) within the TLR genes may influence host-pathogen interactions and can have an impact on the progression of infectious diseases. The present study aimed to investigate the genotype distribution of TLR2 (2029C/T, rs121917864; 2258G/A, rs5743708), TLR4 (896A/G, rs4986790), and TLR9 (- 1237T/C, rs5743836; - 1486T/C, rs187084; 1174G/A, rs352139; and 2848C/T, rs352140) polymorphisms in 149 children and adolescents with infectious mononucleosis (IM) and 140 healthy individuals. The potential association of TLR SNPs with the clinical manifestations of EBV infection was also studied. The presence of TLR2, TLR4, and TLR9 SNPs was identified by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). EBV DNA loads were detected by quantitative real-time PCR assay. The TLR4 896 GG and the TLR9 1174 GA genotypes were associated with an increased risk of EBV-related IM in examined patients (p = 0.014 and p = 0.001, respectively). The heterozygous genotype of the TLR4 896A/G SNP was associated with an increased risk of elevated liver enzyme levels and leukocytosis (p < 0.05). Our preliminary study revealed that the TLR4 896A/G and the TLR9 1174G/A polymorphisms seem to be related to the course of acute EBV infection in children and adolescents.

Dynamically Expressed miR-BART16 Functions as a Suppressor of CAND1 in Infectious Mononucleosis Caused by Epstein-Barr Virus in Children.

OBJECTIVE: MiR-BART16 is a newly discovered Epstein-Barr Virus-encoded microRNA (miRNA). We aimed to explore the role of EBV-miR-BART16 in infectious mononucleosis (IM). METHODS: Peripheral blood lymphocyte subsets were analyzed in 30 IM and 10 healthy children by flow cytometry. MiR-BART16 and its targets were measured by real-time PCR, western blot, ELISA, and dual-luciferase assay. RESULTS: Serum miR-BART16 expression was significantly higher in the IM children than that in the healthy children, and was positively correlated with EBV copy number. Receiver operating characteristic analysis revealed serum miR-BART16 could differentiate IM and healthy individuals (P=0.0041). CAND1 was targeted and downregulated by miR-BART16 in an EBV infection-dependent way. CONCLUSIONS: These results highlight that EBV-miR-BART16 plays an important role in regulating the expression of CAND1 to affect pediatric IM.

Infectious mononucleosis, immune genotypes, and non-Hodgkin lymphoma (NHL): an InterLymph Consortium study.

PURPOSE: We explored the interaction between non-Hodgkin lymphoma (NHL), infectious mononucleosis (IM) history, and immune-related genotypes in a pooled case-control analysis. METHODS: A total of 7,926 NHL patients and 10,018 controls from 12 case-control studies were included. Studies were conducted during various time periods between 1988 and 2008, and participants were 17-96 years of age at the time of ascertainment/recruitment. Self-reported IM history and immune response genotypes were provided by the InterLymph Data Coordinating Center at Mayo Clinic. Odds ratios (OR) were estimated using multivariate logistic regression, and interactions were estimated using the empirical Bayes method. PACT was used to account for multiple comparisons. RESULTS: There was evidence of an interaction effect between IM history and two variants on T-cell lymphoma (TCL) risk: rs1143627 in interleukin-1B (IL1B) (pinteraction = 0.04, ORinteraction = 0.09, 95% confidence interval [CI] 0.01, 0.87) and rs1800797 in interleukin-6 (IL6) (pinteraction = 0.03, ORinteraction = 0.08, 95% CI 0.01, 0.80). Neither interaction effect withstood adjustment for multiple comparisons. There were no statistically significant interactions between immune response genotypes and IM on other NHL subtypes. CONCLUSIONS: Genetic risk variants in IL1B and IL6 may affect the association between IM and TCL, possibly by influencing T-cell activation, growth, and differentiation in the presence of IM, thereby decreasing risk of immune cell proliferation.

Changes in mRNA expression of members of TGFB1-associated pathways in human leukocytes during EBV infection.

Transforming growth factor ß 1 (TGFB1) likely contributes to the pathogenesis of Epstein-Barr virus (EBV)-mediated cancer. A microarray containing 59 probes for detecting mRNA of members of TGFB1-associated pathways was developed. mRNA expression of TGFB1 receptors and members of connected pathways were examined in peripheral blood leukocytes of patients during acute EBV infection and after recovery. TGFB1 and TGFBR2 mRNA expression was increased in patients with EBV infection. Similarly, mRNA expression of protein kinase C (PRKCB), MAP3K7, PDLIM7, and other members of TGFB1 and NF-κB signaling pathways increased. A shift of mRNA transcript variant expression of some key members (TGFBR2, PRKCB, and NFKBIB) of involved signaling pathways was detected. After the patients' recovery, most of the altered mRNA expression has been normalized. We speculate that in patients with EBV infection, members of TGFB1-associated pathways contribute to the suppression of proapoptotic and induction of pro-survival factors in leukocytes. The modulation of TGFB1-associated pathways may be considered as a potential risk factor in the development of EBV-associated tumors in patients with acute EBV infection.

Sequence Variation of Epstein-Barr Virus: Viral Types, Geography, Codon Usage, and Diseases.

One hundred thirty-eight new Epstein-Barr virus (EBV) genome sequences have been determined. One hundred twenty-five of these and 116 from previous reports were combined to produce a multiple-sequence alignment of 241 EBV genomes, which we have used to analyze variation within the viral genome. The type 1/type 2 classification of EBV remains the major form of variation and is defined mostly by EBNA2 and EBNA3, but the type 2 single-nucleotide polymorphisms (SNPs) at the EBNA3 locus extend into the adjacent gp350 and gp42 genes, whose products mediate infection of B cells by EBV. A small insertion within the BART microRNA region of the genome was present in 21 EBV strains. EBV from saliva of U.S. patients with chronic active EBV infection aligned with the wild-type EBV genome with no evidence of WZhet rearrangements. The V3 polymorphism in the Zp promoter for BZLF1 was found to be frequent in nasopharyngeal carcinoma cases from both Hong Kong and Indonesia. Codon usage was found to differ between latent and lytic cycle EBV genes, and the main forms of variation of the EBNA1 protein have been identified.IMPORTANCE Epstein-Barr virus causes most cases of infectious mononucleosis and posttransplant lymphoproliferative disease. It contributes to several types of cancer, including Hodgkin's lymphoma, Burkitt's lymphoma, diffuse large B cell lymphoma, nasopharyngeal carcinoma, and gastric carcinoma. EBV genome variation is important because some of the diseases associated with EBV have very different incidences in different populations and geographic regions, and differences in the EBV genome might contribute to these diseases. Some specific EBV genome alterations that appear to be significant in EBV-associated cancers are already known, and current efforts to make an EBV vaccine and antiviral drugs should also take account of sequence differences in the proteins used as targets.

The Challenge of Next Generation Sequencing in a Boy With Severe Mononucleosis and EBV-related Lymphoma.

A severe course of infectious mononucleosis should always lead up to the suspicion of a primary immunodeficiency. We describe the case of a boy with severe mononucleosis accompanied by the development of hemophagocytic lymphohistiocytosis and lymphoma. By whole exome sequencing, we identified a mutation of uncertain significance in CTPS2, a gene closely related to CTPS1, which is involved in a primary immune deficiency with susceptibility to herpesviruses. We discuss the challenge of a correct interpretation of data from whole exome sequencing, questioning whether the CTPS2 variant found in our patient is just an incidental finding or a mutation with variable penetrance.

Genome-wide association and HLA region fine-mapping studies identify susceptibility loci for multiple common infections.

Infectious diseases have a profound impact on our health and many studies suggest that host genetics play a major role in the pathogenesis of most of them. We perform 23 genome-wide association studies for common infections and infection-associated procedures, including chickenpox, shingles, cold sores, mononucleosis, mumps, hepatitis B, plantar warts, positive tuberculosis test results, strep throat, scarlet fever, pneumonia, bacterial meningitis, yeast infections, urinary tract infections, tonsillectomy, childhood ear infections, myringotomy, measles, hepatitis A, rheumatic fever, common colds, rubella and chronic sinus infection, in over 200,000 individuals of European ancestry. We detect 59 genome-wide significant (P < 5 × 10-8) associations in genes with key roles in immunity and embryonic development. We apply fine-mapping analysis to dissect associations in the human leukocyte antigen region, which suggests important roles of specific amino acid polymorphisms in the antigen-binding clefts. Our findings provide an important step toward dissecting the host genetic architecture of response to common infections.Susceptibility to infectious diseases is, among others, influenced by the genetic landscape of the host. Here, Tian and colleagues perform genome-wide association studies for 23 common infections and find 59 risk loci for 17 of these, both within the HLA region and non-HLA loci.

DR3 regulation of apoptosis of naive T-lymphocytes in children with acute infectious mononucleosis.

Acute infectious mononucleosis (AIM) is a widespread viral disease that mostly affects children. Development of AIM is accompanied by a change in the ratio of immune cells. This is provided by means of different biological processes including the regulation of apoptosis of naive T-cells. One of the potential regulators of apoptosis of T-lymphocytes is a death receptor 3 (DR3). We have studied the role of DR3 in the regulation of apoptosis of naive CD4+ (nTh) and CD8+ (nCTL) T-cells in healthy children and children with AIM. In healthy children as well as in children with AIM, the activation of DR3 is accompanied by inhibition of apoptosis of nTh. In healthy children, the stimulation of DR3 resulted in the increase in apoptosis of nCTL. On the contrary, in children with AIM, the level of apoptosis of nCTL decreased after DR3 activation, which is a positive contribution to the antiviral immune response. In children with AIM, nCTL are characterized by reduced level of apoptosis as compared with healthy children. These results indicate that DR3 can be involved in the reduction of sensitivity of nCTL to apoptosis in children with AIM.

Infectious Mononucleosis.

Infectious mononucleosis is a clinical entity characterized by sore throat, cervical lymph node enlargement, fatigue, and fever most often seen in adolescents and young adults and lasting several weeks. It can be caused by a number of pathogens, but this chapter only discusses infectious mononucleosis due to primary Epstein-Barr virus (EBV) infection. EBV is a γ-herpesvirus that infects at least 90% of the population worldwide. The virus is spread by intimate oral contact among teenagers and young adults. How preadolescents acquire the virus is not known. A typical clinical picture with a positive heterophile test is usually sufficient to make the diagnosis, but heterophile antibodies are not specific and do not develop in some patients. EBV-specific antibody profiles are the best choice for staging EBV infection. In addition to causing acute illness, there can also be long-term consequences as the result of acquisition of the virus. Several EBV-related illnesses occur including certain cancers and autoimmune diseases, as well as complications of primary immunodeficiency in persons with the certain genetic mutations. A major obstacle to understanding these sequelae has been the lack of an efficient animal model for EBV infection, although progress in primate and mouse models has recently been made. Key future challenges are to develop protective vaccines and effective treatment regimens.

Primary immunodeficiencies and the control of Epstein-Barr virus infection.

Human primary immunodeficiency (PID) states, where mutations in single immune system genes predispose individuals to certain infectious agents and not others, are experiments of nature that hold important lessons for the immunologist. The number of genetically defined PIDs is rising rapidly, as is the opportunity to learn from them. Epstein-Barr virus (EBV), a human herpesvirus, has long been of interest because of its complex interaction with the immune system. Thus, it causes both infectious mononucleosis (IM), an immunopathologic disease associated with exaggerated host responses, and at least one malignancy, EBV-positive lymphoproliferative disease, when those responses are impaired. Here, we describe the full range of PIDs currently linked with an increased risk of EBV-associated disease. These provide examples where IM-like immunopathology is fatally exaggerated, and others where responses impaired at the stage of induction, expansion, or effector function predispose to malignancy. Current evidence from this rapidly moving field supports the view that lesions in both natural killer cell and T cell function can lead to EBV pathology.

Novel Association of Killer Cell Immunoglobulin-like Receptor Genes with EBV-infectious Diseases in Children.

Killer cell immunoglobulin-like receptors (KIRs) which are mainly expressed on natural killer (NK) cells are implicated in many virus infections. However, it is unclear whether or not KIRs are associated with susceptibility to Epstein-Barr virus (EBV) infection related diseases. Therefore, the purpose of our study was to investigate possible correlation between polymorphisms of KIR genes and infectious mononucleosis (IM)/EBV-associated hemophagocytic lymphohistiocytosis (EBV-HLH). The polymorphisms of KIR genes were detected by polymerase chain reaction with sequence-specific primers (PCR-SSP). The results would contribute to clarify the association of KIRs with EBV induced diseases, and provide new insights into the role of NK cells and innate immune response against viral infections and/or subsequent progression.

No association between rs6897932 in the gene encoding interleukin-7 receptor α and low-grade inflammation or self-reported health - results from the Danish Blood Donor Study.

The T-allele in the single nucleotide polymorphism rs6897932 in the gene encoding the IL-7 receptor α (IL7RA) is associated with reduced risk of autoimmune diseases including multiple sclerosis and also affects the course of HIV infection. Low-grade inflammation (LGI) and self-reported, health-related quality of life (HRQL) are often associated with chronic diseases and widely used in assessing and monitoring health status. The aim of the present study was to evaluate whether the T-allele in rs6897932 is associated with reduced risk of LGI (hsCRP 3-10 mg/L), history of infectious mononucleosis (IM), and HRQL in healthy individuals. A total of 17, 293 healthy Danish individuals from the Danish Blood Donor Study were included in the analyses. We tested rs6897932 as a predictor of LGI, self-reported IM, and HRQL in univariable and multivariable models stratified by sex. No associations between rs6897932 and LGI, self-reported IM or HRQL were found in men or women. This suggests that rs6897932 is not associated with general inflammation, and the reported associations between the T-allele in rs6897932 with several autoimmune diseases may be mediated through effects on a restricted part of the immune system.

A genetic basis for infectious mononucleosis: evidence from a family study of hospitalized cases in Denmark.

BACKGROUND: Circumstantial evidence from genome-wide association and family studies of various Epstein-Barr virus-associated diseases suggests a substantial genetic component in infectious mononucleosis (IM) etiology. However, familial aggregation of IM has scarcely been studied. METHODS: We used data from the Danish Civil Registration System and the Danish National Hospital Discharge Register to study rate ratios of IM in a cohort of 2 823 583 Danish children born between 1971 and 2011. Specifically, we investigated the risk of IM in twins and in first-, second-, and third-degree relatives of patients with IM. In the analyses, IM was defined as a diagnosis of IM in a hospital contact. Effects of contagion between family members were dealt with by excluding follow-up time the first year after the occurrence of IM in a relative. RESULTS: A total of 16 870 cases of IM were observed during 40.4 million person-years of follow-up from 1977 to 2011. The rate ratios and the associated 95% confidence intervals were 9.3 (3.0-29) in same-sex twins, 3.0 (2.6-3.5) in siblings, 1.9 (1.6-2.2) in children, 1.4 (1.3-1.6) in second-degree relatives, and 1.0 (0.9-1.2) in third-degree relatives of IM patients. The rate ratios were very similar for IM in children (aged 0-6 years) and older children/adolescents (aged 7-19 years). CONCLUSIONS: We found evidence of familial aggregation of IM that warrants genome-wide association studies on IM disease etiology, especially to examine commonalities with causal pathways in other Epstein-Barr virus-related diseases.

Interleukin 28B gene polymorphisms and Epstein-Barr virus-associated lymphoproliferative diseases.

OBJECTIVES: Single-nucleotide polymorphisms (SNPs) near the interleukin (IL) 28B gene encoding a type III interferon (IFN-λ) are the most important genetic predictors of treatment response to hepatitis C virus (HCV). This retrospective study was undertaken to determine any association between IL28B SNPs and the development of viraemia in Epstein-Barr virus (EBV)-driven acute infectious mononucleosis (IM) and post-transplant lymphoproliferative disease (PTLD). METHODS: Genomic DNA extracted from plasma from 45 EBV seropositive controls and 46 acute IM, 23 non-PTLD (transplant) and 21 PTLD patients was tested by PCR for 2 SNPs within IL28B. EBV DNA levels were tested in IM and PTLD samples by a real-time quantitative PCR. RESULTS: No significant differences were seen in SNP frequencies at rs12979860 and rs8099917 in IM and PTLD patients compared to EBV seropositive controls and transplant patients. EBV DNA levels were lower in IM and PTLD patients with CC (a favourable genotype in HCV) at rs12979860 compared to non-CC genotypes (p = 0.055). Acute IM patients with CC had significantly lower levels of EBV DNA in plasma compared to those with non-CC genotypes (p = 0.011). CONCLUSIONS: Genotype CC may influence anti-viral responses of IFN-λ, thereby allowing better control of EBV viraemia during lymphoproliferation, particularly in IM.

Primary EBV infection induces an expression profile distinct from other viruses but similar to hemophagocytic syndromes.

Epstein-Barr Virus (EBV) causes infectious mononucleosis and establishes lifelong infection associated with cancer and autoimmune disease. To better understand immunity to EBV, we performed a prospective study of natural infection in healthy humans. Transcriptome analysis defined a striking and reproducible expression profile during acute infection but no lasting gene changes were apparent during latent infection. Comparing the EBV response profile to multiple other acute viral infections, including influenza A (influenza), respiratory syncytial virus (RSV), human rhinovirus (HRV), attenuated yellow fever virus (YFV), and Dengue fever virus (DENV), revealed similarity only to DENV. The signature shared by EBV and DENV was also present in patients with hemophagocytic syndromes, suggesting these two viruses cause uncontrolled inflammatory responses. Interestingly, while EBV induced a strong type I interferon response, a subset of interferon induced genes, including MX1, HERC5, and OAS1, were not upregulated, suggesting a mechanism by which viral antagonism of immunity results in a profound inflammatory response. These data provide an important first description of the response to a natural herpesvirus infection in humans.