Association of EB-virus infection with the post-perfusion syndrome

Prophylactic and Therapeutic EBV Vaccines: Major Scientific Obstacles, Historical Progress, and Future Direction

The Epstein-Barr virus (EBV) infects more than 95% of adults worldwide and is associated with various malignant tumors and immune diseases, imparting a huge disease burden on the human population. Available EBV vaccines are imminent. Prophylactic vaccines can effectively prevent the spread of infection, whereas therapeutic vaccines mainly stimulate cell-mediated immunity and kill infected cells, thus curbing the development of malignant tumors. Nevertheless, there are still no approved EBV vaccines after decades of effort. The complexity of the EBV life cycle, the lack of appropriate animal models, and the limited reports on adjuvant selection and immune responses are gravely impeding progress in EBV vaccines. The soluble gp350 vaccine could reduce the incidence of infectious mononucleosis (IM), which seemed to offer hope, but could not prevent EBV infection. Continuous research and vaccine trials provide deep insights into the structural biology of viruses, the designs for immunogenicity, and the evolving vaccine platforms. Moreover, the new vaccine candidates are expected to achieve further success via combined immunization to elicit both a dual protection of B cells and epithelial cells, and sustainable immunization against infected cells at several phases of infection.

Co-prevalence of human Papillomaviruses (HPV) and Epstein-Barr virus (EBV) in healthy blood donors from diverse nationalities in Qatar

Background

Infections by both human oncoviruses, human Papillomaviruses (HPV) and Epstein–Barr virus (EBV) are very common in the adult human population and are associated with various malignancies. While HPV is generally transmitted sexually or via skin-to-skin contact, EBV is frequently transmitted by oral secretions, blood transfusions and organ transplants. This study aims to determine the prevalence and circulating genotypes of HPV and EBV in healthy blood donors in Qatar.

Methods

We explored the co-prevalence of high-risk HPVs and EBV in 378 males and only 7 females blood donors of different nationalities (mainly from Qatar, Egypt, Syria, Jordan, Pakistan, and India) residing in Qatar, using polymerase chain reaction (PCR). DNA was extracted from the buffy coat and genotyping was performed using PCR and nested-PCR targeting E6 and E7 as well as LMP-1 of HPV and EBV, respectively.

Results

We found that from the total number of 385 cases of healthy blood donors studied, 54.8% and 61% of the samples are HPVs and EBV positive, respectively. Additionally, our data revealed that the co-presence of both high-risk HPVs and EBV is 40.4% of the total samples. More significantly, this study pointed out for the first time that the most frequent high-risk HPV types in Qatar are 59 (54.8%), 31 (53.7%), 52 (49.1%), 51 (48.6%), 58 (47%) and 35 (45.5%), while the most commonly expressed low-risk HPV types are 53 (50.6%), 11 (45.5), 73 (41.7%) and 6 (41.3%), with all the cases showing multiple HPVs infection.

Conclusion

In this study, we demonstrated for the first time that HPV and EBV are commonly co-present in healthy blood donors in Qatar. On the other hand, it is important to highlight that these oncoviruses can also be co-present in several types of human cancers where they can cooperate in the initiation and/or progression of these cancers. Therefore, more studies regarding the co-presence of these oncoviruses and their interaction are necessary to understand their cooperative role in human diseases.

Epstein-Barr Virus Infection in the Development of Neurological Disorders

Epstein-Barr Virus (EBV) is a ubiquitous human herpesvirus that contributes to the etiology of diverse human cancers and auto-immune diseases. EBV establishes a relatively benign, long-term latent infection in over 90 percent of the adult population. Yet, it also increases risk for certain cancers and auto-immune disorders depending on complex viral, host, and environmental factors that are only partly understood. EBV latent infection is found predominantly in memory B-cells, but the natural infection cycle and pathological aberrations enable EBV to infect numerous other cell types, including oral, nasopharyngeal, and gastric epithelia, B-, T-, and NK-lymphoid cells, myocytes, adipocytes, astrocytes, and neurons. EBV infected cells, free virus, and gene products can also be found in the CNS. In addition to the direct effects of EBV on infected cells and tissue, the effect of chronic EBV infection on the immune system is also thought to contribute to pathogenesis, especially auto-immune disease. Here, we review properties of EBV infection that may shed light on its potential pathogenic role in neurological disorders.

Primary Infectious Mononucleosis Masquerading as Post-operative Fever in a Young Patient with Cemento-ossifying Fibroma of the Skull Base

The typical presentation of infectious mononucleosis (IM) is characterized by a triad of fever, pharyngitis, and lymphadenopathy. Epstein-Barr virus (EBV) is the most common etiologic agent for IM. Humans are the reservoir for EBV, and it is transmitted via intimate contact between individuals.

This case presents a 19-year-old male with recurrent cemento-ossifying fibroma of the skull base with a complicated post-operative course including bacterial meningitis, cerebrospinal fluid (CSF) leak, and intermittent fevers despite treatment with intravenous cefepime. Head computed tomography (CT) revealed a nonspecific subdural collection that could represent an empyema. However, exploratory craniotomy revealed no empyema. CT chest demonstrated bilateral hilar mediastinal lymphadenopathy and splenomegaly. Blood work for fever of unknown origin was positive for EBV immunoglobulin M, and EBV deoxyribonucleic acid 180,565 IU/mL. 

The diagnosis of EBV IM in this case was elusive because it presented post-operatively, symptoms aligned with the patient’s CSF leak, and he reported no sexual or sick contacts. For post-operative young patients with recurrent fevers of unknown origin, it is important to consider EBV IM in the differential. Earlier diagnosis could have saved the patient unneeded tests, prevented surgical re-exploration, and resulted in a shorter hospital stay.

Viral, bacterial, and fungal infections of the oral mucosa: Types, incidence, predisposing factors, diagnostic algorithms, and management

For millions of years, microbiota residing within us, including those in the oral cavity, coexisted in a harmonious symbiotic fashion that provided a quintessential foundation for human health. It is now clear that disruption of such a healthy relationship leading to microbial dysbiosis causes a wide array of infections, ranging from localized, mild, superficial infections to deep, disseminated life-threatening diseases. With recent advances in research, diagnostics, and improved surveillance we are witnessing an array of emerging and re-emerging oral infections and orofacial manifestations of systemic infections. Orofacial infections may cause significant discomfort to the patients and unnecessary economic burden. Thus, the early recognition of such infections is paramount for holistic patient management, and oral clinicians have a critical role in recognizing, diagnosing, managing, and preventing either new or old orofacial infections. This paper aims to provide an update on current understanding of well-established and emerging viral, bacterial, and fungal infections manifesting in the human oral cavity.

Natural Products Mediated Targeting of Virally Infected Cancer

The role of viral infection in developing cancer was determined in the start of 20th century. Until now, 8 different virus-associated cancers have been discovered and most of them progressed in immunosuppressed individuals. The aim of the present study is to look into the benefits of natural products in treating virally infected cancers. The study focuses on bioactive compounds derived from natural sources. Numerous pharmaceutical agents have been identified from plants (vincristine, vinblastine, stilbenes, combretastatin, and silymarin), marine organisms (bryostatins, cephalostatin, ecteinascidins, didemnin, and dolastatin), insects (cantharidin, mastoparan, parectadial, and cecropins), and microorganisms (vancomycin, rhizoxin, ansamitocins, mitomycin, and rapamycin). Beside these, various compounds have been observed from fruits and vegetables which can be utilized in anticancer therapy. These include curcumin in turmeric, resveratrol in red grapes, S-allyl cysteine in allium, allicin in garlic, catechins in green tea, and β-carotene in carrots. The present study addresses various types of virally infected cancers, their mechanism of action, and the role of different cell surface molecules elicited during viral binding and entry into the target cell along with the anticancer drugs derived from natural products by targeting screening of bioactive compounds from natural sources.

Diagnostic Performance and Comparative Evaluation of the Architect, Liaison, and Platelia Epstein-Barr Virus Antibody Assays

BACKGROUND

Epstein-Barr Virus (EBV) is one of the most prevalent causes of viral infection in humans. EBV infection stage (acute, past, or absent infection) is typically determined using a combination of assays that detect EBV-specific markers, such as IgG and IgM antibodies against the EBV viral capsid antigen (VCA) and IgG antibodies against the EBV nuclear antigen (EBNA). We compared the diagnostic performance and agreement of results between three commercial EBV antibody assays using an EBV performance panel (SeraCare Life Science, Milford, MA, USA) as a reference.

METHODS

EBV antibody tests of EBV VCA IgM, VCA IgG, and EBNA IgG antibodies were performed by the Architect (Abbott Diagnostics, Wiesbaden, Germany), Liaison (DiaSorin, Saluggia, Italy), and Platelia (Bio-Rad, Marnes-la-Coquette, France) assays. Agreement between the three assays was evaluated using 279 clinical samples, and EBV DNA and antibody test results were compared.

RESULTS

The three EBV antibody assays showed good diagnostic performance with good and excellent agreement with the performance panel (kappa coefficient, >0.6). The overall VCA IgM positivity rate was higher in EBV DNA-positive samples than in EBV DNA-negative samples for all three EBV antibody assays (P=0.02). The three EBV antibody assays exhibited good agreement in results for the clinical samples.

CONCLUSIONS

The diagnostic performance of the three EBV antibody assays was acceptable, and they showed comparable agreement in results for the clinical samples.

Epstein-Barr Virus Epidemiology, Serology, and Genetic Variability of LMP-1 Oncogene Among Healthy Population: An Update

The Epstein-Barr virus (EBV) is a DNA lymphotropic herpesvirus and the causative agent of infectious mononucleosis. EBV is highly prevalent since it affects more than 90% of individuals worldwide and has been linked to several malignancies including PTLDs, which are one of the most common malignancies following transplantation. Among all the EBV genes, most of the recent investigations focused on studying the LMP-1 oncogene because of its high degree of polymorphism and association with tumorigenic activity. There are two main EBV genotypes, Type 1 and 2, distinguished by the differences in the EBNA-2 gene. Further sub genotyping can be characterized by analyzing the LMP-1 gene variation. The virus primarily transmits through oral secretions and persists as a latent infection in human B-cells. However, it can be transmitted through organ transplantations and blood transfusions. In addition, symptoms of EBV infection are not distinguishable from other viral infections, and therefore, it remains questionable whether there is a need to screen for EBV prior to blood transfusion. Although the process of leukoreduction decreases the viral copies present in the leukocytes, it does not eliminate the risk of EBV transmission through blood products. Here, we provide a review of the EBV epidemiology and the genetic variability of the oncogene LMP-1. Then, we underscore the findings of recent EBV seroprevalence and viremia studies among blood donors as a highly prevalent transfusion transmissible oncovirus.

Primary Epstein-Barr virus infection

Epstein-Barr virus (EBV) infects about 90% of adults worldwide. It is the main cause of infectious mononucleosis, which is observed most frequently in adolescents. The disease can last several weeks and is characterized by lymphocytosis, sore throat, lymphadenopathy, and fatigue. Exposure to oral secretions during deep kissing has been identified as the major source for primary EBV infection in adolescents. Oral secretions are also thought to be the source for younger children through intimate intact or sharing food and eating utensils, although this has not been confirmed. Unlike most acute viral illnesses such as influenza, the incubation period of symptomatic primary EBV infection is unusually long, lasting about six weeks. Diagnosis is typically made by heterophile antibody tests and/or EBV-specific antibody tests. Long-term consequences may result from acquisition of the virus, including nasopharyngeal carcinoma and lymphomas. Nevertheless, there remains a surprising dearth of knowledge regarding the establishment of an immune response to persistent EBV infection, especially during the incubation period. This lack of knowledge has impaired our ability to develop an effective prophylactic EBV vaccine, despite various attempts. Our greatest challenges in EBV research are to develop a prophylactic vaccine and devise treatment strategies for persons already infected with EBV.

Prevalence and molecular profiling of Epstein Barr virus (EBV) among healthy blood donors from different nationalities in Qatar

BACKGROUND

The Epstein-Barr virus (EBV) is the causative agent of infectious mononucleosis. EBV is highly prevalent lymphotropic herpesvirus and has been linked to several malignancies. Transmission is generally by oral secretions, but can be through blood transfusions and organ transplantations. This study aimed to determine the seroprevalence, viremia rates, and circulating genotypes of EBV in healthy blood donors in Qatar.

METHODS

Blood samples from 673 blood donors of different nationalities residing in Qatar (mainly Qatar, Egypt, Syria, Jordan, Pakistan, and India) were collected and tested for anti-EBV capsid (VCA; IgG & IgM), nuclear (EBNA; IgG), and early (EA-D; IgG) antigens. Avidity testing was determined when active infection was suspected. DNA was extracted from the buffy coat and subjected to EBV-DNA quantification using qRT-PCR. Genotyping was performed using nested-PCR targeting EBV-EBNA2 gene, and phylogeny by sequence analysis of the LMP-1 gene.

RESULTS

97.9% (673/659) of the samples were seropositive as indicated by the presence VCA-IgG, while 52.6% (354/673) had detectible EBV-DNA. EBV seroprevalence and viremia rates increased significantly with age. Genotyping of 51 randomly selected samples showed predominance of Genotype 1 (72.5%, 37/51) as compared to genotype 2 (3.5%), and mixed infections were detected in 4% of the samples. Sub-genotyping for these samples revealed that the Mediterranean strain was predominant (65.3%), followed by B95.8 prototype and North Carolina strains (12.2% each), and China1 strain (6%).

CONCLUSION

As a first study to evaluate EBV infection in highly diverse population in Qatar, where expatriates represent more than 85% of the population, our results indicated high seroprevalence and viremia rate of EBV in different nationalities, with genotype 1 and Mediterranean strain being predominant. Clinical significance of these finding have not been investigated and shall be evaluated in future studies.

Infectious mononucleosis

Infectious mononucleosis is a clinical entity characterized by pharyngitis, cervical lymph node enlargement, fatigue and fever, which results most often from a primary Epstein-Barr virus (EBV) infection. EBV, a lymphocrytovirus and a member of the γ-herpesvirus family, infects at least 90% of the population worldwide, the majority of whom have no recognizable illness. The virus is spread by intimate oral contact among adolescents, but how preadolescents acquire the virus is not known. During the incubation period of approximately 6 weeks, viral replication first occurs in the oropharynx followed by viremia as early as 2 weeks before onset of illness. The acute illness is marked by high viral loads in both the oral cavity and blood accompanied by the production of immunoglobulin M antibodies against EBV viral capsid antigen and an extraordinary expansion of CD8(+) T lymphocytes directed against EBV-infected B cells. During convalescence, CD8(+) T cells return to normal levels and antibodies develop against EBV nuclear antigen-1. A typical clinical picture in an adolescent or young adult with a positive heterophile test is usually sufficient to make the diagnosis of infectious mononucleosis, but heterophile antibodies are not specific and do not develop in some patients especially young children. EBV-specific antibody profiles are the best choice for staging EBV infection. In addition to causing acute illness, long-term consequences are linked to infectious mononucleosis, especially Hodgkin lymphoma and multiple sclerosis. There is no licensed vaccine for prevention and no specific approved treatment. Future research goals are development of an EBV vaccine, understanding the risk factors for severity of the acute illness and likelihood of developing cancer or autoimmune diseases, and discovering anti-EBV drugs to treat infectious mononucleosis and other EBV-spurred diseases.

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.

Human viruses and cancer

The first human tumor virus was discovered in the middle of the last century by Anthony Epstein, Bert Achong and Yvonne Barr in African pediatric patients with Burkitt's lymphoma. To date, seven viruses -EBV, KSHV, high-risk HPV, MCPV, HBV, HCV and HTLV1- have been consistently linked to different types of human cancer, and infections are estimated to account for up to 20% of all cancer cases worldwide. Viral oncogenic mechanisms generally include: generation of genomic instability, increase in the rate of cell proliferation, resistance to apoptosis, alterations in DNA repair mechanisms and cell polarity changes, which often coexist with evasion mechanisms of the antiviral immune response. Viral agents also indirectly contribute to the development of cancer mainly through immunosuppression or chronic inflammation, but also through chronic antigenic stimulation. There is also evidence that viruses can modulate the malignant properties of an established tumor. In the present work, causation criteria for viruses and cancer will be described, as well as the viral agents that comply with these criteria in human tumors, their epidemiological and biological characteristics, the molecular mechanisms by which they induce cellular transformation and their associated cancers.

Progress and problems in understanding and managing primary Epstein-Barr virus infections

Epstein-Barr virus (EBV) is a gammaherpesvirus that infects a large fraction of the human population. Primary infection is often asymptomatic but results in lifelong infection, which is kept in check by the host immune system. In some cases, primary infection can result in infectious mononucleosis. Furthermore, when host-virus balance is not achieved, the virus can drive potentially lethal lymphoproliferation and lymphomagenesis. In this review, we describe the biology of EBV and the host immune response. We review the diagnosis of EBV infection and discuss the characteristics and pathogenesis of infectious mononucleosis. These topics are approached in the context of developing therapeutic and preventative strategies.

Efficacy of Epstein-Barr virus removal by leukoreduction of red blood cells

BACKGROUND

Epstein-Barr virus (EBV) infection results in life-long carriage of latent virus in B lymphocytes in the majority of the adult population, including blood donors. The removal of EBV from red blood cell (RBC) components by leukoreduction was assessed.

STUDY DESIGN AND METHODS

Sixteen randomly selected fresh AS-5 units were leukoreduced by filtration. B lymphocytes from preleukoreduction specimens and mononuclear cells (MNCs) from postleukoreduction specimens were assayed for EBV DNA with sensitive real-time polymerase chain reaction (PCR).

RESULTS

EBV genomes were detected in CD19+ B cells in 14 of 16 preleukoreduced RBC units. EBV genomic copy number in the units ranged from 0.18 to 96.84 per 10(5) B lymphocytes representing approximately 135 to 72,630 total EBV genomes per bag. Leukoreduction rendered all but one unit EBV-negative by PCR. The lone PCR-positive unit after leukoreduction amplified 1.2 EBV genome copies from MNCs recovered from the entire unit of leukoreduced RBCs; this unit had the highest EBV viral load before leukoreduction (72,630 EBV genomes).

CONCLUSIONS

These results indicate that a 4-log reduction of EBV genomic copy number can be achieved with leukoreduction of RBC units and renders most RBC units EBV-negative by sensitive PCR.

Epstein-Barr virus-recent advances

Epstein-Barr virus is a tumorigenic herpes virus that is ubiquitous in the adult population. The virus is generally spread to and between young children through salivary contact, and only causes clinical illness where primary infection is delayed until adolescence or beyond, when an intense immunopathological reaction leads to the symptoms of infectious mononucleosis in roughly 50% of cases. More than 90% of the world's population carry Epstein-Barr virus as a life-long, latent infection of B lymphocytes. Recent data show that by mimicking B-cell antigen-activation pathways the virus enters the long-lived memory B lymphocyte pool where it evades immune elimination by severely restricting its own gene expression. By influencing B-cell survival mechanisms Epstein-Barr virus may induce tumours such as B lymphoproliferative disease and Hodgkin's disease. Vaccines are being developed to prevent and/or treat these conditions, but an animal model is required to study pathogenesis before a rational vaccine strategy can be formulated.

Haematological associations of Epstein-Barr virus infection

Epstein-Barr virus (EBV) is one of eight human herpesviruses and is ubiquitous. Primary infection with EBV in childhood is generally silent, but often causes overt diseases such as infectious mononucleosis (IM) and lymphoproliferative disorders (LPD). The latter occurs in immunologically compromised individuals. Historically, EBV has been thought to be aetiologically linked to human malignancies such as EBV genome-positive Burkitt's lymphoma (BL) and nasopharyngeal carcinoma (NPC). Furthermore, studies using recent developments in molecular and immunological diagnostic approaches have suggested that this virus has a causative role in a spectrum of human diseases of previously unknown pathogenesis, including chronic active EBV infection syndrome (CAEBV), EBV-related haemophagocytic lymphohistiocytosis (HLH), and certain disorders such as EBV genome-positive T-cell lymphoma, natural killer (NK) cell leukaemia/lymphoma, Hodgkin's disease (HD) and gastric carcinoma. This chapter reviews recent progress regarding EBV-associated diseases.

Determination of the number of Epstein-Barr virus genomes in whole blood and red cell concentrates

The risk of Epstein-Barr virus (EBV) infection after blood transfusion has been controversially discussed. Little is known about EBV transmission via buffy-coat-depleted red cell concentrates (RCC). In this study, we determined the number of EBV genomes in RCC of EBV-seropositive donors in comparison to whole blood. RCC were prepared from whole blood donations by using the 'top and bottom system'. Leucocyte content was significantly reduced in RCC in comparison to whole blood (0.47 x 10(9) vs. 2.3 x 10(9) per unit; P < 0.001). As B cells are expected to harbour EBV genomes, we analysed the number of B lymphocytes in both types of blood products. There was a significant reduction of B cell content from a median value of 90 x 10(6) in whole blood to 0.2 x 10(6) in RCCs (P < 0.001). The number of EBV genomes was estimated at a median value of seven from 10(6) B cells in the peripheral blood of healthy, EBV-seropositive blood donors by means of a polymerase chain reaction (PCR) assay. By calculation, one unit of RCC may contain an average of one to two EBV genomes, in contrast to a whole blood unit, which is likely to harbour an average of 600 to 700 EBV genomes. It is concluded that the use of leucocyte depletion systems significantly reduces the number of EBV genomes in erythrocyte concentrates. Thus, leucocyte reduced blood products appear to minimize the risk of EBV infection.

Fulminant hepatitis due to Epstein-Barr virus infection

Epstein-Barr virus infection is a benign disease, which may occasionally be fatal, particularly in children. Epstein-Barr virus infection is rare in elderly subjects and appears to have a self-limited course. An unusual case of fulminant hepatitis due to primary Epstein-Barr virus infection in a 62-year-old male 18 days after a cardiosurgical operation and blood transfusions is described in the present paper. Post-mortem examination of the liver showed massive hepatic necrosis. The etiology was established by increase in IgM antibodies to Epstein-Barr virus (titer 1:3.120) in serum and by cellular expression of Epstein-Barr virus DNA in liver tissue.

Infectious mononucleosis in young children

A case of infectious mononucleosis (IM) in a two-year-old patient is presented. The clinical presentation and diagnosis of IM in young children are discussed.

Epstein-Barr virus as an agent of haematological disease

Epstein-Barr virus (EBV) encodes genes that permit its persistence in human B lymphocytes and genes that ensure its replication in epithelial cells. Immune restraints on the virus are usually so effective that most EBV infections are limited to a minute fraction of B lymphocytes and of epithelial cells. As a result, most EBV infections are never symptomatic. Occasionally, the virus causes disease, often with the cooperation of the immune system or other less characterized cofactors. Infectious mononucleosis, a generally self-limited lymphoproliferative illness common in adolescents and young adults, is due to primary EBV infection and to the brisk cellular immune response it elicits. Lymphoproliferative disorders of EBV-infected B cells arise almost exclusively when cellular immunity is grossly compromised. EBV-positive Burkitt's lymphoma contain a translocated and deregulated c-myc oncogene and EBV-positive non-Hodgkin's lymphomas are characterized by the presence of Reed-Sternberg's and Hodgkin's cells, features that have not been directly linked to EBV. Many recent observations, however, including evidence that virus infection precedes malignant transformation and is often associated with a characteristic pattern of viral gene expression, provide continued interest in the relationship between the virus and these haematological malignancies.

Cancer morbidity in blood recipients--results of a cohort study

Blood transfusions involve the transfer of relatively large volumes of body fluids and cellular material between individuals. A variety of pathogens like viruses, some of which are associated with development of certain tumours, are known to be transmitted by this route. Blood recipients were identified during 1981-1982 in the register of the hospital blood centre, and in-patients by the in-patient and discharge register of the hospital. Tumour occurrence and vital status were determined by means of the population-based regional tumour register. Age, gender and calendar-year specific rates from the general population were used to calculate expected values. In a cohort study of 3177 blood recipients, increased numbers of malignant lymphomas [13 vs. 4.8 expected, standard morbidity ratio (SMR) 2.70 95% confidence interval (CI) 1.44-4.62] and skin cancers [12 vs. 5.2 expected, SMR 2.29, 95% CI 1.19-4.01] were seen 3 to 9 years after transfusion. In a second cohort study of 29,910 hospitalised patients, a total of 37 (29.8 expected) malignant lymphomas was found in 28,338 patients with no transfusion and 10 (2.73 expected) in 1572 patients with a transfusion, 3 to 9 years after the hospitalisation. The incidence rate ratio between these groups was 3.11 (95% CI 1.56-6.20) using a Mantel-Haenszel estimator with age stratification. Non-melanomatous skin cancers had an incidence ratio of 2.74 (95% CI 1.25-6.00). We conclude that, in the cohorts discussed here, malignant lymphomas and skin cancer occur more often in blood recipients than in controls. It remains to be established whether this is due to factors covariating with transfusion or by the transfusion itself. Further studies on these putative associations are warranted, as are analytical studies of the epidemiology of malignant lymphomas, especially non-Hodgkin's lymphoma, whose aetiology is still poorly understood.

Viruses and the blood

Haematological syndromes attributed to viruses demonstrate geographical variations in incidence and great dependence on host factors. Severe haematological disease is the exception rather than the rule in dengue virus infection, and probably depends at least in part on the host immune response to the virus. The increased incidence of hepatitis-associated aplasia in east Asia may reflect distribution of an infectious agent, an environmental toxin, or genetic predisposition, but probably represents some combination of these factors. Agents with apparently universal distribution, such as parvovirus B19 and Epstein-Barr virus, are associated with bone marrow failure only in a very narrow range of hosts. These examples teach us that viral causes cannot automatically be excluded from the differential diagnosis of syndromes whose occurrence is rare or apparently sporadic. Further investigation of these syndromes should include more detailed characterization of host factors, particularly immunological characteristics, and possible infectious and toxic cofactors which are associated with morbidity.

Blood-borne Infections Associated with Transfusion

The epidemic of acquired immunodeficiency syndrome (AIDS) and the realization that transmission of human immunodeficiency virus is caused by homologous blood transfusion have changed the way physicians and their patients view the safety of hemotherapy. Considering that nearly four million patients receive the lifesaving benefits of blood transfusions every year in the United States, we need to recognize and reduce the inherent biological complications of this therapy. Currently, a major concern is the transmission of blood-borne infectious agents and the establishment of persistent infection in transfusion recipients, which is apparently facilitated by suppression of the recipient's hematopoietic and immune systems. Education of blood donors, patients, and attending physicians regarding infectious complications of transfusion is essential and remains the most effective procedure for making rational decisions. Before giving blood transfusions, astute physicians should calculate a risk/benefit ratio and communicate it to the patient or family. Potential recipients of transfusions can be assured that the blood supply is safer now than at any time in the past, although there is still a very small risk for the transmission of infectious agents that cause chronic diseases, such as hepatitis, AIDS, neuropathies, and leukemias. It is essential that everyone understands that the goal of a zero-risk blood supply is not attainable. Recent developments in molecular biology and biotechnology, however, provide opportunities for further reduction of infectious complications of blood transfusions.

Orthotopic liver transplantation, Epstein-Barr virus, cyclosporine, and lymphoproliferative disease: a growing concern

Lymphoproliferative disease (LPD) is a well-recognized complication of both solid organ and bone marrow transplantations. The occurrence of LPD in these settings is related in part to the use of the immunosuppressive agent cyclosporine. We report 12 cases of LPD after orthotopic liver transplantations in 132 pediatric patients. Lymphoproliferative disease occurred as one of three clinical syndromes: (1) lymphadenopathic, (2) systemic, and (3) lymphomatous. Effective management of LPD with excisional therapy or reduction of immunosuppressive medications or both resulted in the survival of 7 of 12 patients. In an alarming and increasing percentage of patients after orthotopic liver transplantation, progressive LPD develops with lethal outcome (5/12 patients). Early recognition of LPD and aggressive intervention may improve outcome in this group.

Epstein-Barr virus and human diseases: recent advances in diagnosis

Since the discovery of Epstein-Barr virus (EBV) from a cultured Burkitt's lymphoma cell line in 1964, the virus has been associated with Burkitt's lymphoma, nasopharyngeal carcinoma, and infectious mononucleosis. During the recent decade, EBV has been etiologically implicated in a broad spectrum of human diseases. The precise role of this virus in these diseases is not well understood, but clearly, defective immunosurveillance against the virus may permit an uncontrolled proliferation of EBV-infected cells. As a result, a growing number of cases of EBV-associated B-cell proliferative diseases or lymphoma have been noted in patients with primary and acquired immunodeficiencies. These lymphoproliferative diseases and others, such as chronic mononucleosis syndrome, are leading to new areas of investigation which are providing information regarding the pathogenetic mechanisms of EBV-induced diseases. The early accurate diagnosis of EBV infection can be achieved by performing EBV-specific serology, detecting for EBV-determined nuclear antigen in tissues, establishing spontaneous lymphoid cell lines, and using molecular hybridization techniques for demonstrating the presence of viral genome in affected lesions.

Changing patterns of infectious diseases

In the 20 years that have passed since I received my medical degree, some of the most evident, striking, and interesting changes in patterns of diseases have occurred among those due to transmissible agents. Among other changes are the recognition of new diseases, new clinical manifestations for old diseases, new ecologic niches for traditional pathogens, and new modes of disease transmission. Implicated causes for these changes include alterations in lifestyle such as sexual behaviour, leisure activity, and dietary trends, along with the impact of immigration and the effects of medical progress. A review of these changing patterns demonstrates the dynamic nature of medicine and suggests lessons for medical education.

Non-A, non-B viral hepatitis

Non-A, non-B hepatitis is a newly recognized disease entity. Although initially described as a transfusion related viral infection, the disease can occur in sporadic, endemic, and epidemic settings. There are no confirmed, reproducible serologic tests for associated antigens or antibodies, but electron microscopy has revealed virus-like particles of different sizes. Nonspecific laboratory tests of hepatic dysfunction, especially alanine aminotransferase, are currently utilized to diagnose non-A, non-B hepatitis in patients and may be used to implicate blood donor carriers of this virus. The existence of an infectious non-A, non-B hepatitis agent and proof of a chronic carrier state in humans have been documented by transmission studies in chimpanzees. Cross challenge studies in chimpanzees, as well as some epidemiologic data, suggest that more than one agent causes non-A, non-B hepatitis.

Epstein-Barr virus-related serology in marrow transplant recipients

Serial sera from 50 marrow transplant recipients were examined for their spectra and titers of antibodies to EBV-specific antigens. Immediately before or after transplant, blood products passively transferred antibodies to EB viral capsid antigen (VCA) and EBV nuclear antigen (EBNA). In most recipients, passively-transferred antibodies were replaced by endogenous antibodies regardless of whether donor or recipient had EBV antibodies before transplantation. Commencement or resumption of endogenous EBV antibody production was not associated with signs of infectious mononucleosis or heterophil antibody responses. Antibodies to VCA rose to abnormally high titers, followed successively by antibody to early antigens (EA), and disproportionately low levels of anti-EBNA. Unusually high anti-VCA and anti-EA levels persisted when tests of immune function returned to normal. Antibodies to other herpes group viruses showed no consistent changes. We conclude that (1) EBV does not cause significant clinical problems in marrow transplant recipients; (2) persistent EBV infection can become established or reestablished in the presence of antibodies to EBV; (3) marrow transplant recipients show the same exaggerated immune response to EBV as other immunodeficient patients; and (4) the pattern of EBV-specific antibodies may be a more sensitive measure of defective cell-mediated immunity than most conventional tests of immune function.

Persistent transfusion-associated infectious mononucleosis with transient acquired immunodeficiency

Trauma and blood transfusion led to profound, persistent infectious mononucleosis in a 21 year old man. Splenectomy and trauma had apparently produced transient immune deficiency which was complicated by osteomyelitis of a fractured tibia. The transfused blood probably contained Epstein-Barr virus (EBV). Infectious mononucleosis had ensued 25 days after a blood transfusion was given, antibodies to EBV appeared in his serum, and the infectious mononucleosis persisted for nearly two years. His immunity returned gradually to normal, but because of nonunion of the fracture site, which was infected by Staphylococcus aureus, above-knee amputation was required. The acquired, transient immune deficiency to EBV and profound infectious mononucleosis seen in this patient is analogous to inherited, permanent immune deficiency to this virus in the X-linked lymphoproliferative syndrome.

Epstein-Barr virus infection in polytransfused patients with homozygous beta-thalassaemia

The frequency of Epstein-Barr virus (EBV) and hepatitis B virus (HBV) infection has been studied in 149 polytransfused thalassaemic patients and in healthy controls. Evidence for EBV infection was based on the detection of antibodies to viral capsid antigen (anti-VCA) and for HBV infection on the detection of either hepatitis B surface antigen (HBsAg) or hepatitis B surface antibody (anti-HBs). The frequency of anti-VCA was not significantly higher in the patients (16.4%) compared to the controls (69.8%) whereas HBV infection was more frequently observed in the patients (91.3%) than in the controls (17.3%). There was also no evidence of repeated infection or recent infection with EBV in the polytransfused patients. These data suggest that transfusion of stored blood does not represent a significant factor of spread for EBV.