Patients with systemic lupus erythematosus have abnormally elevated Epstein-Barr virus load in blood

Various genetic and environmental factors appear to be involved in systemic lupus erythematosus (SLE). Epstein-Barr virus (EBV) is among the environmental factors that are suspected of predisposing to SLE, based on the characteristics of EBV itself and on sequence homologies between autoantigens and EBV antigens. In addition, higher titers of anti-EBV antibodies and increased EBV seroconversion rates have been observed in SLE patients as compared with healthy control individuals. Serologic responses do not directly reflect EBV status within the body. Clarification of the precise status of EBV infection in SLE patients would help to improve our understanding of the role played by EBV in this disease. In the present study we determined EBV types in SLE patients (n = 66) and normal control individual (n = 63) by direct PCR analysis of mouthwash samples. We also compared EBV load in blood between SLE patients (n = 24) and healthy control individuals (n = 29) using semiquantitative PCR assay. The number of infections and EBV type distribution were similar between adult SLE patients and healthy control individuals (98.5% versus 94%). Interestingly, the EBV burden in peripheral blood mononuclear cells (PBMCs) was over 15-fold greater in SLE patients than in healthy control individuals (mean +/- standard deviation: 463 +/- 570 EBV genome copies/3 microg PBMC DNA versus 30 +/- 29 EBV genome copies/3 microg PBMC DNA; P = 0.001), suggesting that EBV infection is abnormally regulated in SLE. The abnormally increased proportion of EBV-infected B cells in the SLE patients may contribute to enhanced autoantibody production in this disease.     

Epstein-Barr virus antibodies in patients with ataxia-telangiectasia and other immunodeficiency diseases

An unusual antibody response to the Epstein—Barr virus (EBV) has been noted in patients with ataxia—telangiectasia. Of a group of 16 such patients 8 were found to have antibodies in their serum to the EBV viral capsid antigen (VCA), and 4 of them also had antibodies to the EBV early antigen (EA); antibodies to the nuclear antigen (EBNA), however, were absent in 3 of the 8. The antibody pattern persisted for more than 2 years in the patients available for follow-up study. In comparison, of 24 patients with various other immunodeficiency syndromes 9 were found to have EBV-VCA antibodies in their serum, but none of the 9 had EA antibodies and 3 lacked EBNA antibodies. Two other groups of subjects, all of whom had EBV-VCA and EBNA antibodies in their serum late after an EBV infection, were also studied; 82 had infectious mononucleosis and 55 were healthy and had no such history. EA antibodies were detected in 45 of the first group during the acute phase of the illness but persisted in only 6 of the 68 who were followed up for more than 2 years, and they were detected in only 7 of the second group.All eight lymphoblastoid cell lines established from the peripheral blood of the four patients with ataxia—telangiectasia who are still available for follow-up study express EBV-VCA, whereas most similar cell lines established from normal individuals express only EBNA. In two of these patients cell-mediated immunity, as assessed from lymphocyte transformation induced by mitogens, was markedly decreased but autologous cell-mediated immune regression of EBV-induced transformation of B (bone-marrow-derived)-lymphocytes was normal. The percentage of T (thymus-derived)-helper cells was greatly decreased in two of the three patients in whom it was measured, and the percentage of T-suppressor cells was greatly increased in one of them, but the percentage of total T-lymphocytes was within normal limits in all three.The possible significance of these findings — in particular, the persistence of EA antibodies and the diminished restriction of expression of EA — in the late development of tumours after an EBV infection in patients with ataxia-telangiectasia deserves careful attention. Finally, the apparent correlation between immunoglobulin deficiency and poor or absent EBNA antibody response warrants further study.     

Primary gastric lymphoma is rarely associated with Epstein-Barr virus

Recently, the association of Epstein-Barr virus (EBV) with undifferentiated lymphoepithelioma-like carcinoma and adenocarcinoma of the stomach has been described. In this study of 55 primary gastric lymphomas, most of them belonging to the group of MALT lymphomas, the question of possible EBV involvement has been addressed using in-situ hybridization (ISH) and blot techniques. EBV DNA and/or DNA sequences were found in only two of 24 centroblastic and B-immunoblastic lymphomas and in one anaplastic large cell lymphoma of null cell phenotype. In a further centroblastic lymphoma, a few positive nontumorous (bystander) cells were identified by ISH.     

Epstein-Barr virus recombinants from overlapping cosmid fragments.

Five overlapping type 1 Epstein-Barr virus (EBV) DNA fragments constituting a complete replication- and transformation-competent genome were cloned into cosmids and transfected together into P3HR-1 cells, along with a plasmid encoding the Z immediate-early activator of EBV replication. P3HR-1 cells harbor a type 2 EBV which is unable to transform primary B lymphocytes because of a deletion of DNA encoding EBNA LP and EBNA 2, but the P3HR-1 EBV can provide replication functions in trans and can recombine with the transfected cosmids. EBV recombinants which have the type 1 EBNA LP and 2 genes from the transfected EcoRI-A cosmid DNA were selectively and clonally recovered by exploiting the unique ability of the recombinants to transform primary B lymphocytes into lymphoblastoid cell lines. PCR and immunoblot analyses for seven distinguishing markers of the type 1 transfected DNAs identified cell lines infected with EBV recombinants which had incorporated EBV DNA fragments beyond the transformation marker-rescuing EcoRI-A fragment. Approximately 10% of the transforming virus recombinants had markers mapping at 7, 46 to 52, 93 to 100, 108 to 110, 122, and 152 kbp from the 172-kbp transfected genome. These recombinants probably result from recombination among the transfected cosmid-cloned EBV DNA fragments. The one recombinant virus examined in detail by Southern blot analysis has all the polymorphisms characteristic of the transfected type 1 cosmid DNA and none characteristic of the type 2 P3HR-1 EBV DNA. This recombinant was wild type in primary B-lymphocyte infection, growth transformation, and lytic replication. Overall, the type 1 EBNA 3A gene was incorporated into 26% of the transformation marker-rescued recombinants, a frequency which was considerably higher than that observed in previous experiments with two-cosmid EBV DNA cotransfections into P3HR-1 cells (B. Tomkinson and E. Kieff, J. Virol. 66:780-789, 1992). Of the recombinants which had incorporated the marker-rescuing cosmid DNA fragment and the fragment encoding the type 1 EBNA 3A gene, most had incorporated markers from at least two other transfected cosmid DNA fragments, indicating a propensity for multiple homologous recombinations. The frequency of incorporation of the nonselected transfected type 1 EBNA 3C gene, which is near the end of two of the transfected cosmids, was 26% overall, versus 3% in previous experiments using transfections with two EBV DNA cosmids. In contrast, the frequency of incorporation of a 12-kb EBV DNA deletion which was near the end of two of the transfected cosmids was only 13%.(ABSTRACT TRUNCATED AT 400 WORDS)     

Epstein-barr virus DNA in the cerebrospinal fluid of patients with human immunodeficiency virus infection and central nervous system disorders.

Routine search for herpesvirus types 1-5 by nested polymerase chain reaction revealed Epstein-Barr virus (EBV) DNA in the cerebrospinal fluid (CSF) of ten out of seventy-nine patients with human immunodeficiency virus (HIV) infection and central nervous system (CNS) disorders not associated with the presence of primary CNS lymphomas. One out of the ten CSF samples was positive for EBV DNA only, six were also positive for microbial agents of recognised neurological pathogenicity while the remaining three samples had a high content of HIV p24 Ag. When six available CSF samples out of the ten EBV DNA positive specimens were investigated for an intrathecal EBV antibody response, all six samples proved EBV antibody-free. The concurrent detection of neurotropic infectious agents and the absence of EBV antibodies in the CSF contribute to the uncertainty on the role of EBV in the neurological illness of the patients studied. One hypothesis considered is that the presence of EBV DNA in the CSF of a large fraction of the ten patients under study is an incidental event associated with EBV reactivation in the host's peripheral blood monocytes, but not related to the genesis of neurological disorders.     

Infectious mononucleosis and Epstein-Barr virus

Epstein-Barr virus (EBV) is a gamma-herpesvirus that infects over 90% of the human population worldwide. It is usually transmitted between individuals in saliva, and establishes replicative infection within the oropharynx as well as life-long latent infection of B cells. Primary EBV infection generally occurs during early childhood and is asymptomatic. If delayed until adolescence or later, it can be associated with the clinical syndrome of infectious mononucleosis (also known as glandular fever or 'mono'), an illness characterised by fevers, pharyngitis, lymphadenopathy and malaise. EBV infection is also associated with the development of EBV-associated lymphoid or epithelial cell malignancies in a small proportion of individuals. This review focuses on primary EBV infection in individuals suffering from infectious mononucleosis. It discusses the mechanism by which EBV establishes infection within its human host and the primary immune response that it elicits. It describes the spectrum of clinical disease that can accompany primary infection and summarises studies that are leading to the development of a vaccine designed to prevent infectious mononucleosis.     

Some recent developments in the molecular epidemiology of Epstein-Barr virus infections

We have applied two different recombinant DNA techniques to the study of the epidemiology of Epstein-Barr virus infections. In the first application, cloned subfragments of viral DNA were used as probes to detect EBV DNA in a variety of lymphoproliferative disorders and in lymphoid cell lines. Patients who are epidemiologically unrelated harbor EBV genotypes which can readily be distinguished from each other. Patients who are epidemiologically related (such as mothers and infants) have similar EBV genotypes. Some patients, especially those who are immunocompromised, are infected with two distinct genotypes. In the second application, we have examined the immune response to specific EBV antigens expressed from small cloned viral DNA subfragments. We have identified a group of patients with presumed chronic EBV infection who selectively fail to recognize one subcomponent of the EB nuclear antigen complex.     

Correlative detection of human immunodeficiency virus (HIV) antigen p24 and Epstein-Barr virus DNA in vitro: clinical influence on HIV infection.

The existence of molecular transactivations between EBV and HIV-1, as well as reactivations of EBV latent infections in AIDS patients, have been recently documented. In order to shed more light on the putative association between EBV and HIV, and its role in the evolution to AIDS, we have determined simultaneously p24 protein and EBV DNA in culture supernatants of peripheral blood mononuclear cells from 47 individuals suspected of having HIV infection. The results of the in vitro assays were correlated with the clinical stage of the individuals and their serologic status to EBV. Statistical analysis showed a concordance between HIV infection and in vitro detection of EBV DNA (P < 0.002); particularly, a strong correlation between the presence of EBV DNA and p24 in culture was observed (P < 0.001). These results are consistent with the occurrence of viral interactions, manifested in vitro. However, in our series, the appearance of EBV DNA in culture was not concomitant with an elevation of anti-VCA IgG titers, anti-EA titers or the development of symptomatology, suggestive of a reactivation of a latent EBV infection or a progression of HIV infection. Therefore we conclude that, although interaction between both viruses may take place at the molecular level, there is no clear evidence of the repercussion that this event may have on the clinical course of HIV infection.     

儿童获得性再生障碍性贫血造血干细胞移植后Epstein-Barr病毒血症危险因素及预后分析

目的分析儿童获得性再生障碍性贫血(AA)异基因造血干细胞移植(allo-HSCT)后Epstein-Barr病毒(EBV)血症的危险因素、利妥昔单抗的干预效果及EBV相关疾病的临床转归。方法回顾性分析2010年4月至2018年3月于上海儿童医学中心完成allo-HSCT的257例AA患儿,根据是否发生EBV血症分为:EBV血症组(141例,单纯EBV血症组125例和EBV相关疾病组16例)和非EBV血症组(116例)。采用Cox回归分析危险因素,采用Kaplan-Meier法分析累积生存率,定性资料的组间比较采用卡方检验。结果(1)257例患儿行allo-HSCT后发生EBV血症为141例,发生率为54.86﹪(141/257),其中原发感染为5.67﹪(8/257),再激活为94.33﹪(133/141)。EBV血症的中位发生时间为移植后44 d(13~568 d),单纯EBV血症的移植相关死亡率为6.40﹪(8/125);EBV相关疾病的病死率为56.25﹪(9/16)。(2)利妥昔单抗抢先治疗EBV血症的有效率为88.73﹪(63/71)。(3)与单纯EBV血症组比较,EBV相关疾病组患儿生存率降低,差异有统计学意义(Log-rank P<0.001)。(4)多因素分析结果显示,使用全身照射治疗(TBI)预处理的患儿,发生EBV感染的风险是不使用TBI预处理的患儿1.717倍(95﹪的CI:1.160~2.542);患儿移植物中CD34阳性细胞≥3×10^6个/kg是<3×10^6个/kg患儿的1.775倍(95﹪的CI:1.089~2.894)。结论移植后EBV血症的发生和TBI的应用、输注CD34阳性细胞数大于3×10^6个/kg密切相关,EBV血症进展为EBV疾病后移植相关死亡率升高,对高危患儿应积极予以利妥昔单抗抢先治疗改善预后。     

Early evidence of lymphoproliferative disorder: post-transplant monitoring of Epstein-Barr infection in adult and pediatric patients

Transplant patients are at high risk of post-transplant lymphoproliferative disorder (PTLD). A strong correlation between Epstein-Barr virus (EBV) and PTLD is observed in pediatric patients with primary infection after transplant. Because many patients have responded to reversal of immunosuppressive therapy, an early identification of EBV is essential for the reduction of immunosuppression and/or introduction of antiviral therapy to prevent PTLD. Polymerase chain reaction (PCR) is a specific and sensitive method to identify EBV DNA in blood. The aim of our study was to establish a protocol for monitoring EBV infection in transplanted patients for early identification those at high risk of PTLD. Viral presence in peripheral blood leukocytes (PBL) and serum samples was revealed by Nested PCR; positive specimens were quantified with Real Time PCR (RT-PCR). DNA in PBL was observed in 12 cases and 6 showed EBV in sera. Quantitative analysis showed a wide range of EBV DNA copies in leukocytes that were higher than in sera. Two patients displayed high viral load values in both PBL and sera associated with clinical evidence of PTLD. Our data suggest that the study of the EBV load represents an essential approach in the diagnosis of PTLD and the analysis of serum samples could provide useful information in the post-transplant monitoring of high-risk patients.     

Effect of methotrexate and anti-TNF on Epstein-Barr virus T-cell response and viral load in patients with rheumatoid arthritis or spondylarthropathies

Introduction

There is a suspicion of increased risk of Epstein-Barr virus (EBV)-associated lymphoproliferations in patients with inflammatory arthritides receiving immunosuppressive drugs. We investigated the EBV load and EBV-specific T-cell response in patients treated with methotrexate (MTX) or anti-TNF therapy.

Methods

Data for patients with rheumatoid arthritis (RA) (n = 58) or spondylarthropathy (SpA) (n = 28) were analyzed at baseline in comparison with controls (n = 22) and after 3 months of MTX or anti-TNF therapy for EBV load and EBV-specific IFNγ-producing T cells in response to EBV latent-cycle and lytic-cycle peptides.

Results

The EBV load and the number of IFNγ-producing T-cells after peptide stimulation were not significantly different between groups at baseline (P = 0.61 and P = 0.89, respectively). The EBV load was not significantly modified by treatment, for RA with MTX (P = 0.74) or anti-TNF therapy (P = 0.94) or for SpA with anti-TNF therapy (P = 1.00). The number of EBV-specific T cells was not significantly modified by treatment, for RA with MTX (P = 0.58) or anti-TNF drugs (P = 0.19) or for SpA with anti-TNF therapy (P = 0.39). For all patients, the EBV load and EBV-specific T cells were significantly correlated (P = 0.017; R = 0.21). For most patients, short-term exposure (3 months) to MTX or anti-TNF did not alter the EBV load or EBV-specific T-cell response but two patients had discordant evolution.

Conclusions

These data are reassuring and suggest there is no short-term defect in EBV-immune surveillance in patients receiving MTX or anti-TNF drugs. However, in these patients, long term follow-up of EBV-specific T-cell response is necessary and the role of non-EBV-related mechanisms of lymphomagenesis is not excluded.     

Epstein-Barr virus and cytomegalovirus antibodies in infectious mononucleosis.

A method has been evolved for the demonstration of Epstein-Barr virus (EBV) and cytomegalovirus (CMV) infection in 83 cases of infectious mononucleosis. Serum samples were tested for EBV IgM, anti-VCA IgG, anti-EBNA, CMV IgM and CMV IgG antibodies. An acute-phase sample (or samples) and a convalescence sample were examined in each case, and in 44 cases an additional samples was examined 5-12 months after the illness. Since the different antibodies showed characteristic differences in both titre and persistence, a reliable serodiagnosis has become possible. Acute EBV infection is characterized by the presence of EBV-VCA IgG and EBV IgG antibodies and the lack of anti-EBNA. The latter becomes demonstrable as late as the 4th to 5th month after infection. Mean age of the patients was 19 years. EBV infection was demonstrated in 65%, CMV infection in 18% of the cases. In 12% double infection seemed to be probable.     

Induction of Epstein-Barr virus nuclear antigen and DNA synthesis in a human epithelial cell line after Epstein-Barr virus infection.

The association of Epstein-Barr virus (EBV) with nasopharyngeal carcinoma is supported by the presence of EBV genomes in the epithelial elements of the tumor and by elevated antibody titers to EBV-specific antigens in the patients; the levels of these titers are related to the clinical course of the disease. However, since most laboratory data suggest that EBV is a B-lymphotropic virus, it is unclear how the virus becomes associated with the epithelial elements of the nasopharynx. The purpose of the present work was to find a human model system to study this association. A human epithelial line (U) was found that could be directly infected by EBV, and viral functions, the induction of EBV nuclear antigen and cellular DNA synthesis, were demonstrated. The U line was established in 1957 by the late H. J. Van Kooten (Kok-Doorschodt at the University of Utrecht), and although it is no longer diploid, it exhibits density inhibition. When U cells were infected with EBV, EBV nuclear antigen was expressed in 6 to 16% of the cells, 1 and 2 days after infection with B95-8 virus, but not with the P3HR-1 strain. No evidence for virus replication was obtained; immunofluorescence staining for early antigens and virus capsid antigens gave negative results. Quantitative adsorption experiments for EBV indicated that the adsorption capacity of U cells is significant (60% of Raji cells). The present results also demonstrated that infection with the virus overcomes block(s) in cellular DNA synthesis caused by 5-fluorodeoxyuridine. The induction of DNA synthesis was determined by increased incorporation of [3H]thymidine into the cells. The highest level of isotope incorporation was observed at about 15 h after infection and thereafter decreased. Analysis of the induced DNA indicated that it was of cellular origin.     

Chromosomal localization of the Epstein-Barr virus (EBV) genome in Bloom's syndrome B-lymphoblastoid cell lines transformed with EBV

The localization of the Epstein-Barr virus (EBV) genome in chromosomes of human B-lymphoblastoid cell lines (LCLs) transformed with EBV, and the effect of EBV DNA on the level of sister chromatid exchange (SCE) in Bloom's syndrome (BS) B-LCLs, were examined with chromosomal in situ hybridization techniques using a ³H-EBV DNA probe. EBV DNA was detected in chromosomes 1–5 and 13–15 at specific G band regions in BS as well as in normal B-LCLs, regardless of SCE. Several chromosomal sites (1p31, 1q31, 4q22–24, 5q21, 13q21, 14q21) carrying EBV DNA seemed to be very characteristic in normal as well as in BS B-LCLs. There was no statistically significant difference in silver grain counts due to EBV DNA and their distribution in different chromosomes or groups among normal and BS B-LCLs with normal and high SCE. These findings strongly indicate that EBV infection did not introduce a correcting factor for BS SCE.     

Epstein-Barr virus infection in the neonatal period and in childhood

In an attempt to detect and characterize congenital, neonatal and early childhood EBV infections, a prospective sero-epidemiological study was undertaken in 112 newborn infants and their mothers, 25 additional newborns undergoing exchange transfusion, 114 randomly selected hospitalized infants aged 0 to 3 years, and 109 siblings and parents of these infants. Leukocyte culture was attempted in all the newborns and in 25 pre- and post-transfusion.The findings of EBV seroconversion in six patients without clearly apparent illness, infectious mononucleosis in only one case with significant EBV antibody rise, seroreversion in three cases in early childhood, higher newborn than maternal EBV antibody titres in three cases and the establishment of two permanent lymphoblastoid cell lines from newborns following exchange transfusion raise the possibility of abortive primary EBV infection in early life. Congenital or neonatal infections following exchange transfusions, however, could not be substantiated with certainty since the EBV antibodies did not persist at follow-up except possibly in two cases. Parenteral transmission of the EB virus by exchange transfusion at birth is probably prevented by the presence of EBV antibodies in either donor or recipient.     

Killer cell immunoglobulin-like receptor gene polymorphisms predispose susceptibility to Epstein-Barr virus associated hemophagocytic lymphohistiocytosis in Chinese children

Epstein-Barr virus associated hemophagocytic lymphohistiocytosis (EBV-HLH) has a high mortality rate among children. The pathogenesis of, and underlying predisposing factors for, EBV-HLH are as yet unclear; however, natural killer cells may play a key role in progression of the disease. This study attempted to determine whether killer cell immunoglobulin-like receptor (KIR) gene polymorphisms are responsible for susceptibility to EBV-HLH. Of the 125 children with EBV infection studied, 59 had EBV-HLH and 66 patients had EBV associated infectious mononucleosis (IM) without HLH. The control group was 146 normal children without immune deficiency. KIR polymorphisms were determined by polymerase chain reaction with sequence-specific primers. KIR polymorphism data were analyzed using the X(2) test or Fisher's exact test. The overall observed carrier frequency (OF) of KIR2DS5 was significantly higher in EBV-HLH patients than in IM patients and normal controls (49.2% versus 31.8%, P = 0.048; 49.2% versus 31.5%, P = 0.018, respectively), and the odds ratios (95% confidence interval) were 2.071 (1.001-4.286) and 2.101(1.132-3.900) respectively. The OF of KIR3DS1 was significantly higher in the EBV-HLH patients than in the IM patients (47.4% versus 24.6%, P = 0.012), but not different from normal controls. In summary, KIR polymorphisms may be involved in the development of EBV-HLH, with KIR2DS5 promoting susceptibility to this disease. The obtained KIR data will enrich the understanding of genetic relationships among diseases associated with EBV infection in children.     

Laboratory diagnosis of Epstein-Barr virus infection

Laboratory confirmation of EBV infection requires proper methods and schema of investigation adequate to aim of diagnostic procedure. In paper the results of routine diagnostic tests of EBV infection performed in Department of Virology NIH in 2005-2006 years was included and also, evaluation of usefulness of different laboratory methods was done. Based on results of ELISA tests 10,7% routine investigated subjects was classified as primary EBV infection, 20,1% was seronegative, 7,4% was classified as reactivation of latent infection and serological markers in 45,6% subjects pointed past EBV infection. Positive result of PCR method was obtain in 11,2% samples subjected of routine laboratory investigation. Comparison of specific and non-specific serological methods results (ELISA versus tests of heterophile antibodies) showed the high percentage of false negative results in children tested by non-specific tests. PCR results in serum samples from patients with primary infection (confirmed by serological tests) were positive in 15% cases only. Based on analyzed results it could be stated that reliable confirmation of infectious mononucleosis, as primary EBV infection, is detection of specific IgM antibodies and in case of heterophile antibodies tests the possibility of false negative results, mainly in children, must be taken into account. The most proper samples for PCR method are whole blood, sections of tissue or cells from swabs.     

Assessment of immunological changes in Epstein-Barr virus co-infection in Egyptian chronic HCV patients

Epstein-Barr virus (EBV) plays a major role in liver pathology. Similar to other members of the herpesvirus family, EBV establishes a persistent infection in more than 90% of adults. The aim of this study was to evaluate the impact of EBV and chronic hepatitis C co-infection (HCV) on biochemical and immunological responses in patients. The study was conducted in 62 patients and 33 apparently healthy controls. Patients were divided into three groups: group I, consisting of 31 patients with chronic hepatitis C infection (CHC), group II, consisting of eight patients with EBV infection and without HCV infection and group III, consisting of 23 patients with EBV and chronic HCV. The percentage of CD3⁺ cells, helper CD4⁺ cells and CD19⁺ B-cells was measured by flow cytometry. Human interferon-γ (IFN-γ) and interleukin (IL)-15 levels were measured by an ELISA. The levels of liver alanine aminotransferase and aspartate aminotransferase enzymes were higher in EBV/HCV patients compared to that in EBV and HCV mono-infected patients. EBV/HCV patients had significantly reduced percentages of CD3⁺ and CD4⁺ cells compared to EBV patients. Serum IFN-γ levels were significantly reduced in EBV/HCV patients (3.86 pg/mL) compared to CHC patients (6.76 pg/mL) and normal controls (4.69 pg/mL). A significant increase in serum IL-15 levels was observed in EBV/HCV patients (67.7 pg/mL) compared to EBV patients (29.3 pg/mL). Taken together, these observations suggest that HCV and EBV co-infection can potentiate immune response dampening in patients.     

Epstein-Barr virus induces an oxidative stress during the early stages of infection in B lymphocytes, epithelial, and lymphoblastoid cell lines

The study investigates the direct effect of Epstein-Barr virus infection on the oxidative profile of in vitro cultivated human cells. For this purpose, a panel of human EBV target cells presenting heterogeneity in their cellular and culture types (epithelial cells or lymphocytes; primary culture or continuous cell culture) was selected. These cells are purified human B lymphocytes, DG75, 293, and HepG2 cell lines. The oxidative stress was evaluated during the early stages of infection (2, 12, and 24 h) by measuring malondialdehyde, the end product of the lipid peroxidation, as well as the activities of two antioxidant enzymes: catalase and superoxide dismutase. The obtained results were compared with those of the untreated cells and the K562 cell line which has no interaction with EBV. The incubation of the different target cells with EBV induced an oxidative stress in the purified B lymphocytes, DG75, and 293, but not in HepG2 and K562. This oxidative stress was highlighted by an increase in MDA level (P < 0.05), which began 2 h after the addition of the virus and persisted after 12 and 24 h. Simultaneously, a decrease in catalase and superoxide dismutase activities was observed (P < 0.05), suggesting an alteration of the molecular mechanisms promoting cellular resistance to reactive oxygen species (ROS). The efficiency of EBV infection, assessed by viral DNA PCR amplification, was confirmed in 293 and DG75 but not in HepG2, which was in total concordance with their oxidative profiles. In conclusion, the EBV infection of B and epithelial cells leads to the establishment of an oxidative stress which can play a key role during the viral transformation.     

Structure of defective DNA molecules in Epstein-Barr virus preparations from P3HR-1 cells.

Epstein-Barr virus (EBV), isolated from P3HR-1 cells, induces early antigen and viral capsid antigen upon infection of human B-lymphoblasts. The strong early antigen- and viral capsid antigen-inducing activity is only observed in P3HR-1 virus preparations harboring particles with defective genomes, suggesting that this biological activity is directly associated with the defective DNA population. After infection of EBV genome-carrying Raji or EBV genome-negative BJAB cells, defective genomes of P3HR-1 EBV DNA are replicated in excess, depending on the multiplicity of infecting EBV particles. Hybridization of the DNA from such infected cells with 32P-labeled EBV DNA after HindIII cleavage reveals six hypermolar fragments. Mapping of these fragments shows that they form one defective genome unit containing four nonadjacent regions (alpha, beta, gamma, and delta) of the nondefective P3HR-1 EBV DNA. Two of the segments (alpha and beta) contain ca. 17 and 13 megadaltons, respectively, from the terminal regions of the P3HR-1 genome, whereas the two smaller segments (gamma and delta) contain ca. 3.7 and 3.0 megadaltons, respectively, originating from the central portion of the genome. In the defective molecule, the regions gamma and delta are present in the opposite orientation compared with nondefective P3HR-1 EBV DNA. Tandem concatemers are formed by fusion of the alpha and beta regions. Our model suggests that tandem concatemers of three defective genome units can be packaged into virions in P3HR-1 cells.