Epstein-Barr Virus Herpesvirus Research Articles

The equine herpesvirus 2 E1 open reading frame encodes a functional chemokine receptor.

Several herpesviruses contain open reading frames (ORFs) that encode potential homologs of eucaryotic genes. Equine herpesvirus 2 (EHV-2) is a gammaherpesvirus related to other lymphotropic herpesviruses such as herpesvirus saimiri and Epstein-Barr virus. The E1 ORF of EHV-2, a G protein-coupled receptor homolog, shows 31 to 47% amino acid identity with known CC chemokine receptors. To investigate whether E1 may encode a functional receptor, we cloned the E1 ORF and expressed it in stably transfected cell lines. We report here the identification of the CC chemokine eotaxin as a functional ligand for the EHV-2 E1 receptor. Chemokines are likely to play a role in the regulation of immune functions in equine hosts during EHV-2 infection and, via interaction with E1, may affect viral replication and/or escape from immune responses.

A model for persistent infection with Epstein-Barr virus: The stealth virus of human B cells

Most adult humans are infected benignly and for life with the herpesvirus Epstein-Barr virus. EBV has been a focus of research because of its status as a candidate tumor virus for a number of lymphomas and carcinomas. In vitro EBV has the ability to establish a latent infection in proliferating B lymphoblasts. This is the only system available for studying human herpesvirus latency in culture and has been extremely useful for elucidating how EBV promotes cellular growth. However, to understand how EBV survives in the healthy host and what goes awry, leading to disease, it is essential to know how EBV establishes and maintains a persistent infection in vivo. Early studies on the mechanism of EBV persistence produced inconclusive and often contradictory results because the techniques available were crude and insensitive. Recent advances in PCR technology and the application of sophisticated cell fractionation techniques have now provided new insights into the behavior of the virus. Most dramatically it has been shown that EBV in vivo does not establish latency in a proliferating lymphoblast, but in a resting memory B cell. The contrasting behaviors of being able to establish a latent infection in proliferating B blasts and resting memory B cells can be resolved in terms of a model where EBV performs its complete life cycle in B lymphocytes. The virus achieves this not by disrupting normal B cell biology but by using it.

Association with the cellular export receptor CRM 1 mediates function and intracellular localization of Epstein-Barr virus SM protein, a regulator of gene expression.

Splicing and posttranscriptional processing of eukaryotic gene transcripts are linked to their nuclear export and cytoplasmic expression. Unspliced pre-mRNAs and intronless transcripts are thus inherently poorly expressed. Nevertheless, human and animal viruses encode essential genes as single open reading frames or in the intervening sequences of other genes. Many retroviruses have evolved mechanisms to facilitate nuclear export of their unspliced mRNAs. For example, the human immunodeficiency virus RNA-binding protein Rev associates with the soluble cellular export receptor CRM 1 (exportin 1), which mediates nucleocytoplasmic translocation of Rev-HIV RNA complexes through the nuclear pore. The transforming human herpesvirus Epstein-Barr virus (EBV) expresses a nuclear protein, SM, early in its lytic cycle; SM binds RNA and posttranscriptionally activates expression of certain intronless lytic EBV genes. Here we show that both the trans-activation function and cytoplasmic translocation of SM are dependent on association with CRM 1 in vivo. SM is also shown to be associated in vivo with other components of the CRM 1 export pathway, including the small GTPase Ran and the nucleoporin CAN/Nup214. SM is shown to be present in the cytoplasm, nucleoplasm, and nuclear envelope of transfected cells. Mutation of a leucine-rich region (LRR) of SM inhibited CRM 1-mediated cytoplasmic translocation and SM activity, as did leptomycin B, an inhibitor of CRM 1 complex formation. Surprisingly, however, leptomycin B treatment and mutation of the LRR both led to SM becoming more tightly attached to intranuclear structures. These findings suggest a model in which SM is not merely a soluble carrier protein for RNA but rather is bound directly to intranuclear proteins, possibly including the nuclear pore complex.

Human herpesviruses in chronic fatigue syndrome.

We have conducted a double-blind study to assess the possible involvement of the human herpesviruses (HHVs) HHV6, HHV7, Epstein-Barr virus (EBV), and cytomegalovirus in chronic fatigue syndrome (CFS) patients compared to age-, race-, and gender-matched controls. The CFS patient population was composed of rigorously screened civilian and Persian Gulf War veterans meeting the Centers for Disease Control and Prevention's CFS case definition criteria. Healthy control civilian and veteran populations had no evidence of CFS or any other exclusionary medical or psychiatric condition. Patient peripheral blood mononuclear cells were analyzed by PCR for the presence of these HHVs. Using two-tailed Fisher's exact test analyses, we were unable to ascertain any statistically significant differences between the CFS patient and control populations in terms of the detection of one or more of these viruses. This observation was upheld when the CFS populations were further stratified with regard to the presence or absence of major axis I psychopathology and patient self-reported gradual versus acute onset of disease. In tandem, we performed serological analyses of serum anti-EBV and anti-HHV6 antibody titers and found no significant differences between the CFS and control patients.

The physiologic reservoir of Epstein-Barr virus does not map to upper aerodigestive tissues.

The human Epstein-Barr herpesvirus (EBV) has distinct oncogenic potential, but with over 90% of the adult world population infected, malignancy is a rare outcome of carrier status. However, EBV's association with over half of Hodgkin's and non-Hodgkin's lymphomas as well as several solid tumors, notably nasopharyngeal carcinoma, makes EBV-linked malignancies one of the largest single cancer entities. EBV is a B-lymphotropic virus, well controlled by surveillant T cells in immunocompetent hosts. To determine the presence and site of principal virus reservoirs is a likely prerequisite for understanding the etiology of EBV-associated tumors. Its near 100% association with nasopharyngeal carcinoma led to postulates that the upper aerodigestive tract tissue may be common sites of persistent latent or low-grade replicating infection. Using a protocol designed to avoid viral crosscontamination, the authors employed polymerase chain reaction to detect genomic EBV DNA sequences in 231 biopsies from different mucosal sites in the upper aerodigestive tract, as well as from salivary gland tissue and neck nodes in individuals not suspected to have EBV-related malignancy. Only two samples, one from oral cavity mucosa and one from parotid gland tissue, were positive for EBV. The observation that oropharyngeal tissue is not the principal EBV reservoir has mechanistic implications for the development of EBV-positive tumors in that locale.

Human herpes virus 8 (Kaposi's sarcoma herpesvirus).

Human herpes virus 8 (HHV-8) is a recently discovered herpesvirus related to Herpesvirus saimiri and Epstein-Barr virus (EBV). It has been assigned to the Rhadinovirus genus (gamma-2 herpesvirus) on the basis of its genomic sequence and structure. HHV-8 is the first member of this genus known to infect humans and it is now evident that it is the likely cause of Kaposi's sarcoma (KS). The virus is present in endothelial and spindle cells of KS, and in HIV disease the presence of HHV-8 in peripheral blood, and/or serum IgG antibodies to HHV-8, predicts the development of AIDS-related KS. HHV-8 can also infect CD19 + B cells and is of aetiological significance in the development of body cavity B cell lymphomas of AIDS. Of note, the translation products of viral open reading frames (ORFs) reveal HHV-8 to be a molecular pirate, capable of producing homologues of several human gene products that may result in alterations in cell cycle arrest, inhibit apoptosis and cell-mediated immune responses, and thus provide the potential for tumour production.

Prevalence of human herpesvirus-8 in skin lesions.

A putative new herpesvirus, designated Kaposi's sarcoma-associated herpesvirus (KSHV) or human herpesvirus-8 (HHV-8) was recently identified in AIDS-related Kaposi's sarcoma. The DNA sequence of the virus is homologous to the gamma-herpesviruses such as herpesvirus Saimiri or Epstein-Barr virus, both of which are tumorigenic, suggesting that this new virus may also be oncogenic. Thus, we determined whether the virus is present in other skin lesions. DNA samples from 118 skin specimens were tested for the HHV-8 sequence by polymerase chain reaction (PCR) and Southern hybridization. The sequences were detected in 13 of 21 samples from Bowen's disease, three of 11 squamous cell carcinomas, three of 11 actinic keratoses, three of seven leucoplakia, one of six from Paget's disease, one of 12 malignant melanoma, one of seven neurofibromas, two of seven chronic dermatites and one of 14 normal skin samples. On sequencing the PCR products, new mutation points were detected. These results suggest that the virus is associated with lesions other than Kaposi's sarcoma and may be more widespread than expected (with a latent level too low to be detected), like the other herpesviruses. Some lesions. e.g. in Bowen's disease or squamous cell carcinoma, may be locally immunosuppressed, allowing the virus to replicate until the copy number is sufficient for detection.

A human B-lymphoblastoid cell line constitutively producing Epstein-Barr herpesvirus and JHK retrovirus

The human B-lymphoblastoid cell line, designated JHK-3, with pre-B-cell characteristics, chronically produces two viruses, Epstein-Barr virus (EBV) and JHK virus, an apparently novel retrovirus. The JHK-3 cells are much more productive of extracellular EBV than the high-producer marmoset line B95-8. The extracellular virus of the JHK-3 EBV strain is relatively fragile, more broadly dispersed in an ultracentrifuged sucrose gradient than the B95-8 EBV and more susceptible to disruption by combined treatment with urea and dithiothreitol. By restriction fragment length polymorphism analysis, the JHK-3 EBV strain resembles the EBV strain FF-41. The JHK-3 cells also produce an incompletely characterized, relatively fragile, enveloped, icosahedral RNA virus that contains Mn(++)-dependent reverse transcriptase. JHK virions measure 85 nm in ultrathin sections, much smaller than other Retroviridae. The JHK virus exhibits a distinctive morphogenesis, most nearly resembling C-type retroviruses. The JHK-3 cell line provides a human cell model for investigating virus/virus interactions and their pathogenetic affects on host cells which chronically and simultaneously produce DNA and RNA viruses.

Human herpesvirus KSHV encodes a constitutively active G-protein-coupled receptor linked to cell proliferation.

Kaposi's sarcoma-associated herpesvirus (KSHV, also known as human herpesvirus 8, or HHV 8) is a virus that is consistently present in Kaposi's sarcoma and in primary-effusion (body-cavity-based) lymphomas, malignancies that occur frequently, but not exclusively, in AIDS patients. KSHV is a gamma herpesvirus with homology to herpesvirus Saimiri and Epstein-Barr virus, both of which can transform lymphocytes. Cloning of a KSHV genome fragment revealed the presence of an open reading frame encoding a putative G-protein-coupled receptor that is homologous to a G-protein-coupled receptor encoded by herpesvirus Saimiri and to human interleukin-8 receptors. Here we show that the KSHV G-protein-coupled receptor is a bona fide signalling receptor which has constitutive (agonist-independent) activity in the phosphoinositide-inositoltrisphosphate-protein kinase C pathway. Furthermore, the KSHV G-protein-coupled receptor stimulates cellular proliferation, making it a candidate viral oncogene.

The Kaposi's sarcoma-associated herpesvirus (human herpesvirus-8) in Kaposi's sarcoma, malignant lymphoma, and other diseases

Two novel nonhuman DNA fragments were discovered in an AIDS-related Kaposi's sarcoma (KS) lesion using representational difference analysis. These sequences belong to a previously unidentified gamma-2-herpesvirus exhibiting homology with Herpesvirus saimiri and Epstein-Barr virus. This virus was named Kaposi's sarcoma-associated herpesvirus (KSHV) and provisionally designated human herpesvirus-8 (HHV-8). KSHV is detectable in more than 90% of classical-Mediterranean, iatrogenic, endemic-African, and AIDS-epidemic KS lesions. In situ PCR studies have demonstrated KSHV in the spindle cells and endothelial cells of KS lesions. KSHV appears to be a transmissible B-lymphotropic herpesvirus. It is detectable in circulating B cells in some HIV-infected patients, and this finding appears to predict the future development of KS among these individuals. KSHV has been identified in a rare and distinct subset of malignant lymphoma referred to as body cavity-based lymphoma but not in other lymphoid neoplasms. KSHV is absent from most other HIV- and non-HIV-associated lymphadenopathies. Further studies should lead to a better understanding of the role of KSHV in the pathogenesis of these disorders and may eventually show that KSHV represents the long sought-after etiologic agent of Kaposi's sarcoma.

Human herpesvirus 8

Human herpesvirus 8 (HHV-8, KSHV) was discovered in 1994 by means of a molecular biology approach which permitted to characterize fragments of its genomic sequence. The partial analysis of nucleotide sequence showed that HHV-8 was closely related to herpesvirus saimiri and Epstein-Barr virus, two members of Gammaherpesvirinae sub-family. So far, the virus has been neither isolated nor observed using electron microscopy. It is only detected by means of polymerase chain reaction (PCR) and molecular hybridization. HHV-8 detection in human tissues is strongly associated with three diseases: Kaposi's sarcoma, body-cavity-based lymphomas and Castleman's disease. This association raises the question of the causative role of HHV-8 in the occurrence of these three disease.

Viruses and human cancers: challenges for preventive strategies.

Virus-associated human cancers provide unique opportunities for preventive strategies. The role of human papilloma viruses (HPV 16 and 18), hepatitis B virus (HBV), Epstein-Barr herpes virus (EBV), and retroviruses (human immunodeficiency virus [HIV] and human T-cell leukemia/lymphoma virus [HTLV]) in the development of common carcinomas and lymphomas represents a major cancer threat, particularly among individuals residing in developing countries, which account for 80% of the world's population. Even though these viruses are not the sole etiological agents of these cancers (as would be the case for infectious diseases), different approaches can be implemented to significantly decrease the incidence of virus-associated malignancies. The first approach is vaccination, which is available for HBV and possibly soon for EBV. The long delay between primary viral infection and development of associated tumors as well as the cost involved with administering vaccinations detracts from the feasibility of such an approach within developing countries. The second approach is to increase efforts to detect pre-cancerous lesions or early tumors using immunovirological means. This would allow early diagnosis and better treatment. The third strategy is linked to the existence of disease susceptibility genes, and suggests that counseling be provided for individuals carrying these genes to encourage them to modify their lifestyles and other conditions associated with increased cancer risks (predictive oncology). Specific recommendations include: a) increase international studies that explore the causes of the large variations in prevalence of common cancers throughout the world; b) conduct interdisciplinary studies involving laboratory investigation and social sciences, which may suggest hypotheses that may then be tested experimentally; and c) promote more preventive and health enhancement strategies in addition to curative and replacement therapies.

KS-Associated Herpesvirus in Skin Lesions from Transplant Recipients

A new human herpesvirus, called Kaposi's sarcoma - associated herpesvirus (KSHV) or human herpesvirus 8 (HHV-8), has been detected in HIV-associated, classic, and non - HIV-associated KS biopsies. DNA sequences of HHV-8 most closely resemble those of Epstein-Barr virus (EBV) and herpesvirus saimiri, both members of the gamma or lymphotropic subfamily of herpesviruses. EBV is implicated in the oncogenesis of Burkitt's lymphoma and nasopharyngeal carcinoma. HHV-8 DNA sequences have also …

Epidemiology, pathogenesis, animal models, and treatment of Sjögrenʼs syndrome

Sjögren's syndrome is characterized by dry eyes (xerophthalmia) and dry mouth (xerostomia). Although general agreement exists about the ocular features of Sjögren's syndrome, significant controversy surrounds the classification criteria for defining the oral component. This has resulted in confusion in both the clinical and the research literature. The recent litigation involving silicone breast implants has forced clinicians to evaluate critically whether the condition of a particular patient fulfills specific diagnostic criteria for Sjögren's syndrome. Research studies have focused on potential genetic and environmental factors in the pathogenesis of Sjögren's syndrome. Studies of various ethnic populations have demonstrated an association with particular HLA-DR and -DQ alleles. However, the associated alleles are different for each ethnic group. No single environmental agent has been identified as a critical cofactor. Studies have concentrated on herpesviruses (Epstein-Barr virus and human herpesvirus type 6), hepatitis C virus, and retroviruses. Epstein-Barr virus isolated from patients has altered the ability to transform and lytically infect particular types of lymphocytes. Hepatitis C can lead to sicca symptoms, even in patients with relatively normal salivary gland biopsy findings. One report of Japanese patients indicated the presence of human T cell lymphotropic virus type I-like tax genes in the salivary biopsy specimens of a subset of patients and no gag, pol, or env sequences; this finding suggested a potential infection by a defective retrovirus. Studies on the pathogenesis have indicated that cytokines produced in the salivary gland are similar to T helper type 1 lymphocytes (interferon gamma).(ABSTRACT TRUNCATED AT 250 WORDS)

Viral exanthems

By the early 20th century, physicians had formally recognized measles, rubella, erythema infectiosum, and roseola infantum as distinct disease entities on the basis of clinical and epidemiologic features. These four diseases are collectively referred to as the classic viral exanthems. The advent of modern virology enabled physicians to search for and eventually find the virus responsible for each of the classic exanthems. As more viral agents were discovered, it was found that many other viruses were capable of producing a morbilliform exanthem with human infection. During the last half of this century, there has been an explosion of new knowledge regarding viral agents that produce exanthems, with four new agents discovered within the past 5 years. In 1992, more than 50 different viruses capable of producing an exanthem have been identified and include enteroviruses (echoviruses, coxsackieviruses), herpesviruses (Epstein-Barr virus, cytomegalovirus, herpes simplex virus, human herpesvirus 6), hepatitis viruses (A, B, C, D, and E), respiratory syncytial virus, adenoviruses, mumps virus, reovirus, and human immunodeficiency virus. Herpes simplex virus (HSV) has been included because of the recent finding of HSV antigens and nucleic acids in the skin lesions of erythema multiforme minor (EM minor), supporting classification of EM minor as an HSV exanthem. Today, the newer exanthems are more likely to be seen by the consulting physician because of the marked reduction in the incidence of measles and rubella with widespread immunization. Specific serologic and virologic tests are available to the clinician to distinguish one viral exanthem from another.

Detection of Herpesvirus DNA in Vitreous and Aqueous Specimens by the Polymerase Chain Reaction

Members of the herpesvirus family, cytomegalovirus (CMV), Epstein-Barr virus (EBV), and herpes simplex virus (HSV), have been recognized as causal agents of chorioretinal inflammatory diseases. We investigated the use of the polymerase chain reaction for the detection of CMV, HSV, and EBV genomes in aqueous, subretinal fluid, and vitreous specimens in patients with clinically diagnosed CMV retinitis. Cytomegalovirus but not HSV or EBV genomic sequences were detected in all of these clinical specimens. We also investigated 18 normal aqueous and eight normal vitreous specimens obtained from patients undergoing cataract or vitrectomy surgery. Cytomegalovirus, HSV, and EBV DNA were not detected in any of the normal aqueous specimens. There was one weakly positive CMV normal vitreous, but none was HSV or EBV positive by the polymerase chain reaction. These results indicate that the polymerase chain reaction may be useful as a rapid and sensitive diagnostic technique to aid in the confirmation of clinical observations.

Generation of specific cytotoxic T cells with a fragment of the Epstein-Barr virus-encoded p63/latent membrane protein.

Human B lymphocytes, transformed by the herpesvirus Epstein-Barr virus, are known to express a characteristic antigen(s) recognized by the cellular immune response. This structure has been termed lymphocyte-determined membrane antigen. Because of the significance of this structure in controlling Epstein-Barr virus infection in vivo, the molecular nature of lymphocyte-determined membrane antigen has been long sought. In this paper, we show that a sequence of 10 amino acids (residues 43-53) from the Epstein-Barr virus-encoded membrane protein p63/latent membrane protein can induce Epstein-Barr virus-specific cytotoxic T cells and, therefore, bears at least one of the lymphocyte-determined membrane antigenic determinants.

Herpesvirus papio contains a plasmid origin of replication that acts in cis interspecies with an Epstein-Barr virus trans-acting function

Herpesvirus papio (HVP) and Epstein-Barr virus (EBV) are closely related biologically and biochemically; lymphoblastoid cells infected with either virus contain episomal viral DNA. The putative origin of replication for EBV plasmids (oriP) has been assigned to a 1,790-base-pair fragment (cis) in the short unique region of the genome which requires a viral function supplied in trans from elsewhere in the genome (J. Yates, N. Warren, D. Reisman, and B. Sugden, Proc. Natl. Acad. Sci. USA 81:3806-3810, 1984). We report here the identification of the putative origin of replication (cis) in HVP; we assigned it to the HVP EcoRI K fragment. The results indicate that the HVP replication process requires both a cis and a trans-acting function, analogous to that found in EBV.

Activation of expression of latent Epstein-Barr herpesvirus after gene transfer with a small cloned subfragment of heterogeneous viral DNA.

We previously found that a form of Epstein-Barr virus with rearranged DNA induces replication of latent Epstein-Barr virus. We now have found that one of three fragments of this rearranged DNA, when cloned in recombinant plasmids and used to transfect cells, can activate expression of several polypeptides from a latent viral genome. The 33-kDa protein that is the product of the active fragment is likely to be responsible for disruption of latency.

Collinear relationships of Herpesvirus Papio DNA to Epstein-Barr Virus DNA

Herpesvirus Papio (HVP) and Epstein-Barr virus (EBV) share both biological and biochemical properties. Since the linkage map of HVP and B95 EBV DNA are now available, the individual restriction fragments of HVP DNA were used as probes to determine the region of DNA homology between the two viral DNAs. In general, a high degree of collinearity was found between HVP DNA and B95 EBV DNA. There are only four small portions of B95 EBV DNA which did not show any homology by blot hybridization, i.e., the center region ( EcoR1 K and part of Sal1 C of B95 DNA), the EcoR1 J region of B95 EBV DNA, and the terminal heterogeneous regions. The results also confirmed our previous data that the homologous sequences of HVP DNA to B95 EBV DNA are scattered throughout most of B95 EBV genome.