A role for a new herpes virus (KSHV) in different forms of Kaposi's sarcoma

Associations of Classic Kaposi Sarcoma with Common Variants in Genes that Modulate Host Immunity

Classic Kaposi sarcoma (CKS) is an inflammatory-mediated neoplasm primarily caused by Kaposi sarcoma-associated herpesvirus (KSHV). Kaposi sarcoma lesions are characterized, in part, by the presence of proinflammatory cytokines and growth factors thought to regulate KSHV replication and CKS pathogenesis. Using genomic DNA extracted from 133 CKS cases and 172 KSHV-latent nuclear antigen-positive, population-based controls in Italy without HIV infection, we examined the risk of CKS associated with 28 common genetic variants in 14 immune-modulating genes. Haplotypes were estimated for IL1A, IL1B, IL4, IL8, IL8RB, IL10, IL12A, IL13, and TNF. Compared with controls, CKS risk was decreased with 1235T/-1010G-containing diplotypes of IL8RB (odds ratio, 0.49; 95% confidence interval, 0.30-0.78; P = 0.003), whereas risk was increased with diplotypes of IL13 containing the promoter region variant 98A (rs20541, alias +130; odds ratio, 1.88; 95% confidence interval, 1.15-3.08; P = 0.01) when considered in multivariate analysis. Risk estimates did not substantially vary by age, sex, incident disease, or disease burden. Our data provide preliminary evidence for variants in immune-modulating genes that could influence the risk of CKS. Among KSHV-seropositive Italians, CKS risk was associated with diplotypes of IL8RB and IL13, supporting laboratory evidence of immune-mediated pathogenesis.

Establishment and maintenance of Kaposi's sarcoma-associated herpesvirus latency in B cells

Kaposi's sarcoma (KS)-associated herpesvirus (KSHV) is the infectious cause of Kaposi's sarcoma and is also associated with two B-cell lymphoproliferative diseases, primary effusion lymphoma and the plasmablastic form of multicentric Castleman's disease. KSHV is also found in the B-cell fraction of peripheral blood mononucleocytes of some KS patients. Despite in vivo infection of B cells and the ability of KSHV to infect many cell types in culture, to date B cells in culture have been resistant to KSHV infection. However, as shown here, the lack of infection is not due to the inability of B cells to support latent KSHV infection. When KSHV DNA is introduced into B cells, the virus is maintained as an episome and can establish and maintain latency over the course of months. As in all primary effusion lymphoma cell lines, there is a low level of spontaneous lytic replication in latently infected BJAB cells. Importantly, viral gene expression is similar to that of primary effusion lymphoma cell lines. Furthermore, the virus can be reactivated to higher levels with specific stimuli and transmitted to other cells, indicating that this is a productive infection. Thus B cells in culture are capable of establishing, maintaining, and reactivating from latency. These studies provide a controlled system to analyze how KSHV alters B cells during KSHV latency and reactivation.

Lymphatic and vascular origin of Kaposi's sarcoma spindle cells during tumor development

The histogenesis of Kaposi's sarcoma (KS) tumor spindle cells (SC) remains controversial but several immunohistochemical studies favor a lymphatic origin. Twenty KS surgical biopsies were analyzed for the coexpression of LANA, CD34, LYVE-1, D2-40, VEGFR-2, VEGFR3 by using double or triple immunostaining. Most of the SC in both early and late KS expressed the lymphatic markers LYVE-1, D2-40 and VEGFR-3 and the blood vascular endothelial/endothelial precursor cell markers CD34 and endothelial stem cell marker VEGFR-2. All the LANA+ SC in early and late KS were LYVE-1+, but only 75% of these LANA+ cells were CD34(+). The CD34(+)/LANA+ cells increased from early- (68.8%) to late-stage KS (82.2%). However, approximately 18% of the LANA+ SC in early KS were CD34(-) but were LYVE-1+, suggesting that resident lymphatic endothelial cells (LEC) are targeted for primary infection by human herpesvirus-8. This LANA+/LYVE-1+/CD34(-) (resident LEC) cell population clearly decreased during the development of KS from early (18.7%) to late KS (2.9%). Thus, in late stages of KS, most SC were LANA+/CD34(+)/LYVE-1+. However, in both early- and late-stage KS, approximately 18% of the SC were CD34(+)/LANA-/LYVE-1 -- and could represent newly recruited endothelial precursor cells, which become infected in the lesion and eventually undergo a phenotype switch expressing LEC markers. Our study apparently indicates that KS represents a unique variant of tumor growth with continues recruitment of tumor precursor cells as well as proliferation and decreased apoptosis of SC.

Human Herpesvirus 8 Infection in Hemodialysis Patients

BACKGROUND

The aim of the present study was to evaluate human herpesvirus 8 (HHV-8) seroprevalence in Greek hemodialysis patients. Patterns of change in HHV-8 serostatus (seroconversions and seroreversions) over time were also evaluated.

METHODS

Serum samples obtained from a cohort of 485 Greek hemodialysis patients were tested for antibodies to HHV-8 by whole virus lysate enzyme-linked immunosorbent assay, and reactive samples were confirmed by means of the orf-73 enzyme-linked immunosorbent assay. HHV-8 seroprevalence at study entry and the incidence of seroreversions and seroconversions per 100 person-years were estimated.

RESULTS

The prevalence of HHV-8 antibodies in Greek hemodialysis patients at enrollment was 7.2%. No univariate associations were established between HHV-8 serostatus and patients' characteristics. Incidences of seroreversions and seroconversions were 16.4/100 person-years (95% confidence interval, 7.1 to 32.3) and 0.28/100 person-years (95% confidence interval, 0.03 to 1.02), respectively. Patients 50 years and younger had an increased probability for seroreversion to HHV-8 antibodies than patients older than 50 years (log-rank test, P = 0.018).

CONCLUSION

We observed a fair number of seroreversions and a low incidence of seroconversion to HHV-8 infection in hemodialysis patients in Greece. Our data provide indirect evidence that HHV-8 transmission in the hemodialysis setting is uncommon.

Chemical library screen for novel inhibitors of Kaposi's sarcoma-associated herpesvirus processive DNA synthesis

Kaposi's sarcoma-associated herpesvirus (KSHV) is the causative agent of Kaposi's sarcoma and certain lymphoproliferative disorders. The role of KSHV lytic replication has been implicated in the tumor pathogenesis. A highly specific molecular complex formed by the KSHV DNA polymerase (POL8) and processivity factor (PF8) is indispensable for lytic viral DNA synthesis and may serve as an excellent molecular anti-KSHV target. The majority of conventional nucleoside-based anti-herpetic DNA synthesis inhibitors require intracellular phosphorylation/activation before they can exert inhibitory activity as competitive substrates for viral DNA polymerases. Novel and more potent inhibitors of KSHV DNA synthesis may be discovered through POL8/PF8-targeted high throughput screening (HTS) of small molecule chemical libraries. We developed a microplate-based KSHV POL8/PF8-mediated DNA synthesis inhibition assay suitable for HTS and screened the NCI Diversity Set that comprised 1992 synthetic compounds. Twenty-eight compounds exhibited greater than 50% inhibition. The inhibitory activity was confirmed for 25 of the 26 hit compounds available for further testing, with the 50% inhibitory concentrations ranging from 0.12+/-0.07 microM (mean+/-S.D.) to 10.83+/-4.19 microM. Eighteen of the confirmed active compounds efficiently blocked KSHV processive DNA synthesis in vitro. One of the hit compounds, NSC 373989, a pyrimidoquinoline analog, was shown to dose-dependently reduce the levels of KSHV virion production and KSHV DNA in lytically induced KSHV-infected BCBL-1 cells, suggesting that the compound blocked lytic KSHV DNA synthesis. HTS for KSHV POL8/PF8 inhibitors is feasible and may lead to discovery of novel non-nucleoside KSHV DNA synthesis inhibitors.

Apoptosis in normal and diseased oral tissues

Apoptotic cell death plays an important role in maintenance of the normal physiological state and in the pathogenesis of diseases in the body. Over the last three decades the molecular mechanisms of apoptosis have been unravelled leading to development of novel therapeutic approaches. This paper aims to present current knowledge of the role of apoptosis in normal oral tissues and in the development of oral diseases.

Correlates of Human Herpesvirus-8 DNA detection among adults in Italy without Kaposi sarcoma

BACKGROUND

The presence of Human Herpesvirus-8 (HHV8) DNA is predictive of Kaposi sarcoma (KS) among patients with HIV-associated or iatrogenic immunosuppression. However, correlates of HHV8-DNA detection in the general population remain undefined.

METHODS

We assessed correlates of HHV8-DNA detection among Italian adults without KS who had antibodies against HHV8-latent nuclear antigen by immunofluorescence assay. HHV8-K6 DNA sequences were detected in peripheral blood mononuclear cells using TaqMan PCR.

RESULTS

Of the 158 subjects 26 (16.5%) had detectable HHV8-DNA [median copies/million cells, 53; (13-2128)]. Adjusted for age, sex, and laboratory, HHV8-DNA was detected more frequently in participants with >7 total residents in the childhood home [OR = 3.7 (1.5-9.1)], >2 younger siblings [OR = 2.6 (1.1-6.5)], and current cardiovascular [OR = 3.6 (1.3-9.7)] or renal [OR = 3.1 (1.2-8.0)] disease. Excluding the participants using immune modulating drugs, HHV8-DNA was more frequent among those with low red blood cells (RBC) [<4.5 10(6)/microl; OR = 5.3 (1.7-16.2)], slightly elevated mean corpuscular volume [>92 microm3/red cell; OR = 2.8 (1.0-7.8)], and mild thrombocytopenia [<151 K/microl; OR = 5.6 (1.9-16.3)].

CONCLUSIONS

Presence of HHV8-DNA in elderly Italians is associated with childhood crowding, low RBCs, and platelets, perhaps indicating roles for early infection and chronic inflammation. These risk factors are the first to be reported for non-immunosuppressed HHV8-seropositive adults.

Reversal of some viral IL-6 electrostatic properties compared to IL-6 contributes to a loss of alpha receptor component recruitment

Human interleukin-6 (hIL-6) is a pleiotropic mediator of activation and proliferation across a large number of different cell types. Human herpesvirus-8 (HHV-8) has been associated with classical and AIDS-related Kaposi's sarcoma (KS). HHV-8 encodes viral IL-6 (vIL-6), a functional homolog of human interleukin-6, that promotes the growth of KS and of some lymphoma cells. Signaling induced by human IL-6 requires recruitment of the glycoprotein gp130, which acts as the signal transducing chain, and of IL-6Ralpha, which is necessary for cognate recognition and high affinity receptor complex formation. In contrast, the formation of a functional complex between vIL-6 and gp130 does not require the presence of IL-6Ralpha. The physico-chemical properties of vIL-6 have been analyzed and compared to those of hIL-6 and of the receptor chains, gp130 and IL-6Ralpha. Interaction sites on vIL-6 involve more hydrophobic residues than those of hIL-6. The electrostatic fields induced by vIL-6 and IL-6Ralpha are repulsive and prevent interaction between vIL-6 and IL-6Ralpha, whereas the electrostatic field induced by hIL-6 steers the complex formation with IL-6Ralpha. Subsequently, electrostatic binding free energy in the vIL-6/IL-6Ralpha complex is destabilizing, whereas it is stabilizing in the complex comprising hIL-6. These properties result from charge reversals between viral and human IL-6, an unusual phenomenon of amino acid substitutions within a homologous protein family. This suggests a selection pressure for vIL-6 to by-pass the IL-6Ralpha control of host defense against virus infection. This selection pressure has yielded the reversal of electrostatic properties of vIL-6 when compared to hIL-6.

HHV-8/KSHV during the development of Kaposi's sarcoma: evaluation by polymerase chain reaction and immunohistochemistry

The human gamma-herpes virus-8 (HHV-8) was first described in AIDS-related Kaposi's sarcoma (KS) tumour samples. In this study, we report comparative studies on paraffin-embedded biopsies of AIDS-related KS (AKS) and endemic KS (EKS) with regard to HHV-8 content as evaluated using polymerase chain reaction (PCR) and immunohistochemistry. DNA was extracted either using Chelex-100 or using Qia-gene kit and was evaluated with the help of a semiquantitative PCR assay. The PCR detection of HHV-8 was more sensitive to the Chelex method than to Qia-gene. The threshold for PCR test sensitivity with the help of serial dilution of DNA was at the level of five plasmid ORF-26 regions, and DNA from 25 body cavity-based lymphoma-1 cells. The results expressed as virus load/actin unit showed progressively higher HHV-8 levels in late (nodular) cases, compared to those in early (patch/plaque) stages. Evaluation of HHV-8 DNA levels in tumour tissues, thus, indicates a correlation between virus load and KS stage. Double immunostaining of spindle cells (SC) in KS biopsies for CD34 and HHV-8/latency-associated nuclear antigen (LANA) showed an increase in double-positive SC in the lesions of nodular AKS and EKS cases, compared to that in plaque and patch stages. However, 10-15% of CD34+/LANA- SC cells were observed during the development from patch to nodular cases of AKS and EKS. Our results indicate that PCR analysis is a simple and sensitive diagnostic method for HHV-8 evaluation in KS tissues, processed for conventional histopathology.

Lymphangioma-like Kaposi sarcoma

BACKGROUND

Lymphangioma-like Kaposi's sarcoma (LLKS) is a rare morphologic expression of Kaposi's sarcoma (KS) that occurs in virtually all of the well-recognized clinical subtypes of the disease and has the potential to mimic other pathologic processes. In this study, we present the clinical and pathological features of four patients with LLKS.

METHODS

Four cases of LLKS were retrieved from the dermatopathology files of our institution. All four tumours were tested immunohistochemically with anti-human herpesvirus-8 (HHV-8) latent nuclear antigen-1 (LNA-1) and anti-CD34 antibodies.

RESULTS

Clinically, each patient presented with violaceous patches, papules or plaques; one patient presented with bullous lesions. All of the LLKS biopsy specimens revealed areas with characteristic light microscopic features of KS. Lymphangioma-like foci consisted of ectatic, irregularly shaped vascular spaces lined by mildly atypical endothelial cells. All tumour cells, including those associated with LLKS foci, showed a strong and diffuse reactivity for anti-HHV-8 LNA-1 and anti-CD34. KS progressed slowly in two patients with adequate follow-up.

CONCLUSIONS

As LLKS can mimic other disease processes, the correct diagnosis relies heavily on the recognition of salient clinical and histological features of conventional KS, including a strong immunohistochemical expression of HHV-8-associated LNA-1 in lesional cells.

AIDS-related cancer in the era of highly active antiretroviral therapy (HAART): a model of the interplay of the immune system, virus, and cancer. "On the offensive--the Trojan Horse is being destroyed"--Part A: Kaposi's sarcoma

The introduction of highly active antiretroviral therapy (HAART), aimed at controlling human immunodeficiency virus (HIV), has been associated with a dramatic decrease in the incidence of acquired immunodeficiency syndrome-Kaposi's sarcoma (AIDS-KS) and the clinical manifestations of KS appear to be less aggressive. The pathogenesis of AIDS-related KS is related to a system of cytokines (e.g., interleukin-6) driven by autocrine and paracrine loops. More recently, human herpesvirus 8 (HHV-8), was discovered to be the putative etiological agent of this disease. This virus encodes several unique open reading frames that are homologs of human cellular proteins involved in cellular regulations, cell proliferation, apoptosis, and immune regulation. The treatment of this disease depends on whether it is "limited" disease or "extensive" disease. For "limited" disease, local therapy or non-bone marrow suppressive agents should be used. For "extensive" disease, new chemotherapeutic agents, such as liposomal anthracycline, which are active and have little adverse reactions, are indicated. The control of HIV infection continues to be essential. Knowledge of the pathogenesis of the disease has led to the development of novel treatment strategies, aimed at the inflammatory or angiogenesis cytokines necessary for growth or at HHV-8 as the target of therapy.

Imatinib-induced regression of AIDS-related Kaposi's sarcoma

PURPOSE

Activation of the platelet-derived growth factor (PDGF) and c-kit receptors has been proposed as important in mediating the growth of AIDS-related Kaposi's sarcoma (KS). We investigated the response of KS to the PDGF receptor (PDGFR)/c-kit inhibitor, imatinib mesylate, and investigated the effect of this therapy on critical signal transduction intermediates.

PATIENTS AND METHODS

Ten male patients with AIDS-related cutaneous KS, which progressed despite chemotherapy and/or highly active antiretroviral therapy, received imatinib mesylate administered orally, 300 mg twice daily. Clinical response was determined by serial tumor measurements. To determine biologic and histologic response, skin lesion biopsies were obtained at baseline and following 4 weeks of therapy.

RESULTS

Five of 10 participants had a partial response by tumor measurements. Biopsies after 4 weeks of therapy demonstrated histologic regression in four of six patients. Four patients' tumor biopsies were assessable for immunohistochemistry end points pre- and post-therapy. These demonstrated inhibition of PDGFR and its downstream effector, extracellular receptor kinase, which is a member of the mitogen-activated protein kinase family. The most common adverse event was diarrhea, which led to dose reduction in six patients.

CONCLUSION

Imatinib mesylate administered orally twice daily for AIDS-related KS results in clinical and histologic regression of cutaneous KS lesions within 4 weeks. These promising results demonstrate that inhibition of the c-kit and/or PDGF receptors may represent an effective strategy for treating KS.

Lymphatic reprogramming of blood vascular endothelium by Kaposi sarcoma-associated herpesvirus

Kaposi sarcoma is considered a neoplasm of lymphatic endothelium infected with Kaposi sarcoma-associated herpesvirus. It is characterized by the expression of lymphatic lineage-specific genes by Kaposi sarcoma tumor cells. Here we show that infection of differentiated blood vascular endothelial cells with Kaposi sarcoma-associated herpesvirus leads to their lymphatic reprogramming; induction of approximately 70% of the main lymphatic lineage-specific genes, including PROX1, a master regulator of lymphatic development; and downregulation of blood vascular genes.

Chips with everything: DNA microarrays in infectious diseases

Two developments are set to revolutionise research in and clinical management of infectious diseases. First, the completion of the human genome project together with the sequencing of many pathogen genomes, and second, the development of microarray technology. This review explains the principles underlying DNA microarrays and highlights the uses to which they are being put to investigate the molecular basis of infectious diseases. Pathogen studies enable identification of both known and novel organisms, understanding of genetic evolution, and investigation of determinants of pathogenicity. Host studies show the complexities of development and activation of both innate and adaptive immunity. Host-pathogen studies allow global analysis of gene expression during pathogenesis. Microarray technology will accelerate our understanding of the complex genetic processes underlying the interaction between microorganisms and the host, with consequent improvements in the diagnosis, treatment, and prevention of infectious diseases.

De novo infection with rhesus monkey rhadinovirus leads to the accumulation of multiple intranuclear capsid species during lytic replication but favors the release of genome-containing virions

Rhesus monkey rhadinovirus (RRV) is one of the closest phylogenetic relatives to the human pathogen Kaposi's sarcoma-associated herpesvirus (KSHV), yet it has the distinct experimental advantage of entering efficiently into lytic replication and growing to high titers in culture. RRV therefore holds promise as a potentially attractive model with which to study gammaherpesvirus structure and assembly. We have isolated RRV capsids, determined their molecular composition, and identified the genes encoding five of the main capsid structural proteins. Our data indicate that, as with other herpesviruses, lytic infection with RRV leads to the synthesis of three distinct intranuclear capsid species. However, in contrast to the inefficiency of KSHV maturation following reactivation from latently infected B-cell lines (K. Nealon, W. W. Newcomb, T. R. Pray, C. S. Craik, J. C. Brown, and D. H. Kedes, J. Virol. 75:2866-2878, 2001), de novo infection of immortalized rhesus fibroblasts with RRV results in the release of high levels of infectious virions with genome-containing C capsids at their center. Together, our findings argue for the use of RRV as a powerful model with which to study the structure and assembly of gammaherpesviruses and, specifically, the human rhadinovirus,KSHV.

ORF73 of herpesvirus Saimiri strain C488 tethers the viral genome to metaphase chromosomes and binds to cis-acting DNA sequences in the terminal repeats

Kaposi's sarcoma (KS)-associated herpesvirus (KSHV), a human oncogenic gamma-2-herpesvirus, transforms human endothelial cells and establishes latent infection at a low efficiency in vitro. During latent infection, only a limited number of genes are expressed, and the circularized viral genome is maintained as a multicopy episome. Latency-associated nuclear antigen (LANA), exclusively expressed during latency, has been shown to have a multifunctional role in KS pathogenesis. LANA tethers the viral episome to the host chromosome, thus ensuring efficient persistence of the viral genome during successive rounds of cell division. Besides episome maintenance, LANA modulates the expression of genes of various cellular and viral pathways, including those of retinoblastoma protein and p53. Herpesvirus saimiri (HVS), another gamma-2-herpesvirus, primarily infects New World primates. Orf73, encoding the nuclear antigen of HVS, is the positional homolog of the LANA gene, and the ORF73 protein has some sequence homology to KSHV LANA. However, the function of ORF73 of HVS has not been thoroughly investigated. In this report, we show that HVS ORF73 may be important for episome persistence and colocalizes with the HVS genomic DNA on metaphase chromosomes. Furthermore, HVS terminal repeats (TRs) contain a cis-acting sequence similar to that in KSHV TRs, suggesting that the LANA binding sequence is conserved between these two viruses. This cis-acting element is sufficient to bind HVS ORF73 from strains C488 and A11, and plasmids containing the HVS C488 TR element are maintained and replicate in HVS C488 ORF73-expressing cells.

Human Herpesvirus-8 Latent Nuclear Antigen-1 Expression in Endemic Kaposi Sarcoma

Human herpesvirus-8 (HHV-8) infection is considered the initiating factor in all forms of Kaposi sarcoma (KS). Latent nuclear antigen (LNA-1) is constitutively expressed in all HHV-8-infected cells. An antibody to LNA-1 has recently become commercially available. The current study addresses the role of immunohistochemistry in the diagnosis of KS, particularly the endemic form. Seven recent cases of KS, 1 atypical vascular lesion in a patient subsequently diagnosed with KS, and 16 endemic cases collected in South Africa in the early 1960s were stained with an antibody to LNA-1. Nine benign vascular lesions and three angiosarcomas were also stained. All 7 recent cases expressed the antigen as did the atypical vascular lesion. Of particular interest was the finding that 10 of the 16 endemic cases were positive. None of the other vascular lesions showed staining. A subset of the endemic lesions was stained for CD31, an antigen universally expressed in KS. CD31 staining was reduced compared with a positive control suggesting that the current study may underestimate the sensitivity of LNA-1 immunohistochemistry in endemic KS because of poor antigen preservation in the archival tissue. Our results confirm the utility of LNA-1 immunohistochemistry as an aid in the diagnosis of KS.

CD8+CD28-T Lymphocytes from HIV-1-Infected Patients Secrete Factors That Induce Endothelial Cell Proliferation and Acquisition of Kaposi's Sarcoma Cell Features

Kaposi's sarcoma (KS) develops more frequently in human immunodeficiency virus type 1 (HIV-1)-infected patients. In this study, we report that molecules released by CD8(+)CD28(-) T lymphocytes from HIV-1-infected patients promote endothelial-cell (EC) growth and induce ECs to acquire spindle cell morphology and upregulation of intercellular adhesion molecule-1 (ICAM-1), E-selectin, and vascular endothelial cell growth factor receptor-3 (VEGFR-3) (a typical feature of the KS cell phenotype). The effects observed on ECs cocultured with in vivo activated CD28(-) cells were partly reproduced when ECs were grown in medium containing interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha). At concentrations similar to those found in the supernatant of in vivo activated CD28(-) cells, the two proinflammatory cytokines sustained EC growth and survival only when combined. We, therefore, conclude that CD28(-) T lymphocytes from HIV-1-infected patients exert their effect on ECs through a mechanism involving both IFN-gamma and TNF-alpha. This finding may have wide implications for our basic understanding of the immunopathology of KS.

Kaposi's sarcoma-associated herpesvirus (human herpesvirus 8) contains hypoxia response elements: relevance to lytic induction by hypoxia

Kaposi's sarcoma (KS)-associated herpesvirus (KSHV), also known as human herpesvirus 8, is an etiologic agent of KS, primary effusion lymphoma (PEL), and multicentric Castleman's disease. We recently demonstrated that hypoxia can induce lytic replication of KSHV in PEL cell lines. Hypoxia induces the accumulation of hypoxia-inducible factors (HIF), and we hypothesized that the KSHV genome may respond to hypoxia through functional hypoxia response elements (HREs). Here, we demonstrate the presence of at least two promoters within the KSHV genome that are activated by hypoxia or hypoxia mimics. One is in the promoter region of the gene for Rta, the main lytic switch gene, and the other is within the promoter region of ORF34, a lytic gene of unknown function. The ORF34 promoter contains three putative consensus HREs oriented in the direction of the gene. Dissection and site-directed mutagenesis studies confirmed that one of the HREs of the ORF34 promoter is functional. Under conditions of hypoxia, the ORF34 promoter was strongly upregulated by HIF-1 alpha and HIF-2 alpha. By contrast, the promoter of the gene for Rta appeared to be preferentially upregulated by HIF-2 alpha. Reverse transcription-PCR analysis revealed that specific messages for ORF34 and ORF50 are upregulated in BCBL-1 cells exposed to hypoxia. An HIF-1 binding and competition assay demonstrated that the HRE sequence from the ORF34 promoter can compete for HIF-1 alpha binding to an erythropoietin HRE oligonucleotide while a mutant sequence cannot. Thus, we demonstrated that a viral gene can be activated by hypoxia through activation of a functional viral HRE. To our knowledge, this is the first example of a functional HRE in a viral promoter.

Molecular genetics of Kaposi's sarcoma-associated herpesvirus (human herpesvirus-8) epidemiology and pathogenesis

Kaposi's sarcoma had been recognized as unique human cancer for a century before it manifested as an AIDS-defining illness with a suspected infectious etiology. The discovery of Kaposi's sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus-8, in 1994 by using representational difference analysis, a subtractive method previously employed for cloning differences in human genomic DNA, was a fitting harbinger for the powerful bioinformatic approaches since employed to understand its pathogenesis in KS. Indeed, the discovery of KSHV was rapidly followed by publication of its complete sequence, which revealed that the virus had coopted a wide armamentarium of human genes; in the short time since then, the functions of many of these viral gene variants in cell growth control, signaling apoptosis, angiogenesis, and immunomodulation have been characterized. This critical literature review explores the pathogenic potential of these genes within the framework of current knowledge of the basic herpesvirology of KSHV, including the relationships between viral genotypic variation and the four clinicoepidemiologic forms of Kaposi's sarcoma, current viral detection methods and their utility, primary infection by KSHV, tissue culture and animal models of latent- and lytic-cycle gene expression and pathogenesis, and viral reactivation from latency. Recent advances in models of de novo endothelial infection, microarray analyses of the host response to infection, receptor identification, and cloning of full-length, infectious KSHV genomic DNA promise to reveal key molecular mechanisms of the candidate pathogeneic genes when expressed in the context of viral infection.

Age-specific seroprevalence of Human Herpesvirus 8 in Mediterranean regions

OBJECTIVE

Human herpesvirus 8 (HHV8) is believed to be transmitted mainly by sexual contact; epidemiological data from Africa show, however, that non-sexual transmission routes may also play an important role. To evaluate better the distribution of HHV8 infection in the Mediterranean area, we performed an age-specific seroprevalence study.

METHODS

Sera were collected from subjects from different geographical areas. The sera were analyzed by immunofluorescence assay (IFA) and enzyme-linked immunosorbent assay (ELISA). A total of 1083 patients were studied, 667 patients from various regions of Italy and 416 from Albania. The patients were stratified into six age groups. Multivariate logistic regression was used to evaluate associations between HHV8 and demographic data.

RESULTS

An overall seropositivity rate of 17.6% was observed. The highest rate was observed in Sardinia (25.0%) and the lowest was found in Albania (13.9%). The prevalence rate increased linearly with age, from 9.7% in patients belonging to the 0-14 years age group to 26.3% for patients more than 59 years old. Seropositivity for HHV8 was significantly associated with membership of the 59 years-plus age group. Rates of seropositivity were significantly higher in patients from central southern Italy (OR = 1.7) and Sardinia (OR = 1.8) than in patients from Albania.

CONCLUSIONS

The data suggest that HHV8 is widespread in the Mediterranean area, including regions like Albania that have not been previously investigated. The statistically significant association between HHV8 seropositivitity and increasing age suggests that non-sexual transmission routes may be involved in the spread of the virus.

Kaposi's sarcoma: aetiopathogenesis, histology and clinical features

Kaposi's sarcoma (KS) represents today one of the most common skin cancers in transplanted Mediterranean subjects and, since the epidemic of human immunodeficiency virus/acquired immune deficiency syndrome, in young unmarried single men. The disease has been associated with the recent identified human herpesvirus (HHV)-8 or KS herpesvirus and its incidence in the general population shows a north to south gradient that parallels the HHV-8 increasing prevalence from Nordic countries to sub-Saharan regions. The identification of the aetiopathogenetic mechanisms (viral agents and immunodeficiency) involved in the pathogenesis of KS, are relevant for identifying susceptible subjects (HHV-8 seropositive subjects), monitoring the immune levels in iatrogenic immune suppressed patients, and developing new therapeutic approaches based on antiviral and immune modulators.

LEARNING OBJECTIVE

This article should enable the reader: (i) to learn about the clinical and molecular aspects of KS in order to have a multidisciplinary approach to a tumour that shows unique features; (ii) to consider the role of viral agents and immunity; and (iii) to recognize properties of an opportunistic neoplasm. The identification of the HHV-8 role in KS pathogenesis should establish a relevant tool in the clinical management of KS patients.

Human herpesvirus 8 (HHV-8) and the etiopathogenesis of Kaposi's sarcoma

OBJECTIVE

To review the current literature on human herpesvirus 8 with particular attention to the aspects related to the etiopathogenesis of Kaposi's sarcoma.

MATERIALS AND METHODS

The authors searched original research and review articles on specific aspects of human herpesvirus 8 infection, including virology, epidemiology, transmission, diagnosis, natural history, therapy, and Kaposi's sarcoma etiopathogenesis. The relevant material was evaluated and reviewed.

RESULTS

Human herpesvirus 8 is a recently discovered DNA virus that is present throughout the world but with major geographic variation. In the Western world, the virus, transmitted mainly by means of sexual contact, is strongly associated with Kaposi's sarcoma and body cavity-based lymphoma and more controversially with multiple myeloma and other non-proliferative disorders. There is no specific effective treatment, but HIV protease inhibitors may play an indirect role in the clearance of human herpesvirus 8 DNA from peripheral blood mononuclear cells of HIV-infected patients. Human herpesvirus 8 DNA is present in saliva, but there are as yet no documented cases of nosocomial transmission to health care workers. The prevalence of human herpesvirus 8 among health care workers is probably similar to that in the general population.

CONCLUSION

Human herpesvirus 8 appears to be, at least in Western Europe and United States, restricted to a population at risk of developing Kaposi's sarcoma. Human herpesvirus 8 certainly has the means to overcome cellular control and immune responses and thus predispose carriers to malignancy, particularly Kaposi's sarcoma. The wide diffusion of Human herpesvirus 8 in classic Kaposi's sarcoma areas appears to represent an important factor in the high incidence of the disease. However, additional co-factors are likely to play a role in the development of Kaposi's sarcoma.

Human herpesvirus 8 infection

Human herpesvirus 8, also known as Kaposi sarcoma-associated herpesvirus, is etiologically associated with Kaposi sarcoma and other rare malignancies. Human herpesvirus 8 infection is common in certain areas of Africa and Italy, but occurs in only 0% to 15% of adult populations in North America and Europe. Reports of human herpesvirus 8 prevalence of 3% to over 50% among children in Central Africa, Brazil, and South Texas suggest that horizontal transmission of human herpesvirus 8 occurs among children. Primary human herpesvirus 8 infection in immunocompetent children is associated with a fever and maculopapular rash.

Detection and quantitation of Kaposi's sarcoma-associated herpesvirus (KSHV) by a single competitive-quantitative polymerase chain reaction

Kaposi's sarcoma-associated herpesvirus is a novel herpesvirus linked to AIDS-related neoplasms. Currently it is difficult to evaluate the number of virions in viral preparation or in samples obtained from patients with Kaposi's sarcoma (KS), since no protocol for determining the plaque forming units of KSHV exists. We constructed a fragment of a different size than the target viral DNA to carry out a competitive-quantitative PCR. Both fragment and viral DNA were added to a single PCR reaction to compete for the same set of primers. By knowing the amount of the competitor added to the reaction, we could determine the number of viral DNA molecules. We used this assay successfully to detect and quantify KSHV genomes from KS skin biopsies and pleural effusion lymphoma, and from different viral preparations. To date, this is the most convenient and economic method that allows an accurate and fast viral detection/quantitation with a single PCR.

Auto-activation of the transforming viral interferon regulatory factor encoded by Kaposi's sarcoma-associated herpesvirus (human herpesvirus-8)

Kaposi's sarcoma-associated herpesvirus (KSHV)/human herpesvirus-8-encoded viral interferon regulatory factor (vIRF) transforms NIH3T3 cells, represses interferon signal transduction and regulates the expression of other KSHV genes. Here, we have shown that vIRF is a transcriptional activator and auto-activates its own expression. Ectopic expression of vIRF activated the vIRF promoter in KSHV-negative 293, COS7, HeLa and BJAB cell lines in a dose-dependent fashion in a reporter assay and the expression of vIRF transcripts from endogenous viral genomes in BCBL-1 and BC-1 cells latently infected with KSHV. Deletion analysis identified two cis elements, named Vac1 and Vac2, in the vIRF promoter that were responsive to vIRF activation. vIRF auto-activation via Vac1 but not Vac2 was repressed by Tis, a transcriptional silencer in the vIRF promoter. Neither Vac1 nor Vac2 contain any interferon-stimulated response element (ISRE)-like sequences and are unresponsive to induction with interferon-beta and -gamma. These results indicate that KSHV uses the mechanism of auto-activation to regulate the expression of a viral transforming protein to efficiently evade host tumour suppressor pathways.

Human papillomavirus, type 40-associated papilloma, and concurrent Kaposi's sarcoma involving the anterior hard palate of an HIV-positive man

A number of oral lesions have been reported in association with HIV, including lesions caused by other viruses such as the epitheliotropic human papillomavirus (HPV). More than 90 types of HPV have been identified, with the less commonly encountered strains of HPV tending to show association with immunodeficiency states. In addition, HIV-infected patients may have Kaposi's sarcoma develop, a malignancy thought to be caused by human herpes virus, type 8. Recent evidence suggests a sexual mode of transmission for this virus. We report an HIV-positive man with a large, HPV type 40-associated papilloma of the anterior palate and a previously undiagnosed focus of Kaposi's sarcoma.

Human herpesvirus 8, Kaposi's sarcoma, and associated conditions

HHV-8 is a recently identified human herpes virus that can produce tumors, most often in immune compromised hosts. The virus is most closely associated with Kaposi's sarcoma, but is also clearly associated with primary effusion lymphomas and multicentric Castleman's disease. The prevalence of HHV-8 infection varies considerably, but is highest among men who have sex with men and others with histories of sexually transmitted diseases and high numbers of lifetime sexual partners. HHV-8 is shed in saliva, and less commonly in genital secretions. Treatment of HHV-8 associated diseases includes reversal of immune compromise either via discontinuation of immunosuppressives or immune reconstitution via antiretroviral regimens. Specific antiviral drug inhibit HHV-8 replication, and can result in responses in certain HHV-8-associated conditions.

Human herpesvirus 8 (HHV-8) detected in two patients with Kaposi's sarcoma-like pyogenic granuloma

AIMS

To report the finding of human herpesvirus 8 (HHV-8) in two patients with Kaposi's sarcoma (KS)-like pyogenic granuloma. This form of pyogenic granuloma closely resembles KS histologically and it has been reported that immunohistochemistry in such lesions may be positive for smooth muscle actin and factor VIII related antigen, which are typically negative in KS. In both patients the lesions were positive for CD31, CD34, smooth muscle actin, and factor VIII related antigen, a profile typical of KS-like pyogenic granuloma. The lesions were tested for the presence of HHV-8 DNA, which to date has been consistently found in all types of KS.

METHODS

The lesions were tested for the presence of HHV-8 DNA using the polymerase chain reaction (PCR). A known HHV-8 positive KS specimen was used as the positive control. Six samples of non-KS vascular skin lesions were used as negative controls for the PCR reaction.

RESULTS

Both lesions were positive on PCR for HHV-8 and the specificity of product was confirmed by direct sequencing. None of the six control vascular skin lesions was positive for HHV-8. These results strongly indicate KS as the true diagnosis and are supported by the reported clinical course in both cases.

CONCLUSIONS

Techniques targeting HHV-8 DNA for detection to confirm a diagnosis of KS are both sensitive and specific. In cases where the differential diagnosis includes KS-like pyogenic granuloma, caution should be taken not to diagnose solely on the basis of immunohistochemistry phenotype. In such cases, PCR targeting HHV-8 DNA sequences is a better diagnostic tool.

A seroprevalence study of human herpesvirus type 8 (HHV8) in eastern and Central Africa and in the Mediterranean area

Human herpes virus type 8 (HHV8) is the major determinant of Kaposi's sarcoma (KS), a neoplasm with wide geographic variations in incidence rates. To assess the prevalence of HHV8 infection among populations with differing rates of KS, we used sera from 1,402 persons (Central Africa: Cameroon, n = 293, age range: 5-40; eastern Africa: Uganda, n = 315, age range: 1-64: Mediterranean area: Egypt, n = 236, age range: 13-19: Italy, blood donors n = 134, age range: 20-67: Italy. HIV seroconverters n = 424, age range: 16-65). Serum samples were tested for antibodies to lytic and latent antigens of HHV8 using two immunofluorescence assays. HHV8 prevalence was evaluated according to geographic area, gender and age groups. Overall, the highest prevalence of HHV8 lytic antigens (47.5%) was recorded among children and adults in Africa. Approximately 40% of children and adolescents from Egypt and of Italian HIV-positive persons (39.9%) were HHV8 seropositive. In eastern and Central Africa and in Egypt, no differences emerged between males and females for both types of HHV8 antibodies. Conversely, Italian females were at lower HHV8 risk than their male counterparts. Moreover the prevalence of HHV8 infection tended to increase with age. This investigation partially confirms that HHV8 infection mirrors incidence rates of KS. The high prevalence of HHV8 infection in newborns, children and adolescents in Egypt, in eastern and in Central Africa strongly suggests the existence of transmission modes other than sexual.

High prevalence of human herpesvirus 8 (HHV-8) infection in south Texas children

Human herpesvirus 8 (HHV-8), also known as Kaposi's sarcoma-associated herpesvirus, is etiologically associated with Kaposi's sarcoma and other rare malignancies. HHV-8 infection is common in certain areas of Africa and Italy, but occurs in only 0-15% of populations in North America and Europe. The epidemiology and prevalence of HHV-8 infection among children in the United States has not been determined, but is assumed to be low based on limited studies. The objective of this study was to determine the seroprevalence and possible risk factors of HHV-8 infection in children living in south Texas. Questionnaire data were collected and HHV-8 serologic tests were performed from a consecutive, non-probability sample of 123 healthy children (ages 4-13 years) attending general pediatric clinics in south Texas. Serum was tested for HHV-8 antibodies by latent immunofluorescence assay and ORF65 enzyme-linked immunosorbent assay confirmed by immunoblot. HHV-8 prevalence and 95 percent confidence intervals were calculated using standard epidemiologic methods. Logistic regression was used to assess independent risk factors associated with HHV-8 seropositivity. The overall prevalence of HHV-8 infection was 26%. No statistically significant associations were exhibited between HHV-8 prevalence and the variables under study. The prevalence of HHV-8 infection among children in south Texas, particularly among those under the age of 12 years, indicates that non-sexual transmission of this virus is likely to occur among this population. Future investigations of larger study samples will be necessary to develop an understanding of specific routes and risk factors of HHV-8 transmission among children in south Texas.

The role of Kaposi's sarcoma-associated herpesvirus (KSHV/HHV-8) in lymphoproliferative diseases

The Kaposi's sarcoma-associated herpesvirus (KSHV), also called human herpesvirus 8 (HHV-8), is found invariably in Kaposi's sarcoma, and compelling evidence suggests that it is an etiologic agent for this disease. KSHV has also been found to be present in a limited subset of lymphoproliferative disorders. Among these are the primary effusion lymphomas, formerly designated body cavity-based lymphomas. This is a rare type of malignant lymphoma which possesses an unusual set of clinical and biologic features, suggesting that it represents a distinct disease entity. This virus is also present in a large proportion of cases of multicentric Castleman's disease, particularly those associated with HIV infection. In addition, KSHV has been implicated in the pathogenesis of multiple myeloma, but many laboratories including our own have been unable to confirm this association. KSHV carries at least 11 open reading frames (ORFs) that encode homologs to cellular proteins involved in signal transduction, cell cycle regulation, inhibition of apoptosis and/or immune modulation. Therefore, it has the genetic machinery of an oncogenic virus. However, only a small proportion of infected people ever develop Kaposi's sarcoma or virus-induced lymphoma, and do so only after a long latency period. This observation reflects the multistep nature of oncogenesis, with viral infection representing only one of these steps. Cofactors such as HIV infection and iatrogenic immunosuppression dramatically increase the risk for developing a KSHV-related malignancy in infected individuals. Understanding the oncogenic and immunologic mechanisms involved in the pathobiology of virus-associated lymphomas is important for the development of targeted therapeutic and preventive approaches.

Update on Kaposi's sarcoma and other HHV8 associated diseases. Part 2: pathogenesis, Castleman's disease, and pleural effusion lymphoma

The pathogenesis of Kaposi's sarcoma (KS) is better understood since the identification of the novel human herpesvirus 8 (HHV8), which can be found in all forms of KS. Viral oncogenesis and cytokine-induced growth, as well as some states of immunocompromise, contribute to its development. Several virally encoded genes--eg, bcl-2, interleukin 6, cyclin D, G-protein-coupled receptor, and interferon regulatory factor--provide key functions on cellular proliferation and survival. Growth promotion of KS is further stimulated by various proinflammatory cytokines and growth factors such as tumour necrosis factor a, interleukin 6, basic fibroblast growth factor, and vascular endothelial growth factor, resulting in a hyperplastic polyclonal lesion with predominant spindle cells derived from lymphoid endothelia. HHV8 has recently been discovered to escape HLA-class-I-restricted antigen presentation to cytotoxic T lymphocytes by increasing endocytosis of MHC class I chains from the cell surface, thus enabling latent infection and immune escape in primary and chronic infection. Multicentric Castleman's disease is a rare lymphoproliferative disorder of the plasma cell type, which has been reported in both HIV-seropositive and HIV-seronegative patients, and which frequently contains HHV8 DNA. Pleural effusion lymphoma, or body-cavity-based lymphoma, belongs to the group of non-Hodgkin B-cell lymphomas characterised by pleural, pericardial, or peritoneal lymphomatous effusions in the absence of a solid tumour mass. Pleural effusion lymphoma has an intermediate immunophenotype lacking B or T lymphocyte antigens and also belongs to the diseases associated with HHV8.

Transcriptional regulation of Kaposi's sarcoma-associated herpesvirus-encoded oncogene viral interferon regulatory factor by a novel transcriptional silencer, Tis

Viral interferon regulatory factor (vIRF) encoded by Kaposi's sarcoma-associated herpesvirus (KSHV) has been shown to transform NIH3T3 and Rat-1 cells, inhibit interferon signal transduction, and regulate the expression of KSHV genes. We had previously characterized the vIRF core promoter and defined a 12-O-tetradecanoylphorbol-13-acetate (TPA)-responsive region in the upstream regulatory sequence of vIRF gene. Here, we have further identified a novel transcriptional silencer, named Tis in this region. Tis represses the promoter activities of vIRF and heterologous herpes simplex virus thymidine kinase genes in both position- and orientation-independent manners. Deletion analysis has identified a cis-element of 23 nucleotides that is essential for the negative regulation. Two Tis-binding protein complexes, named vR1 and vR2, were observed by electrophoretic mobility shift assays using nuclear extracts from both KSHV-negative and -positive cell lines. A sequence fragment GAGTTAATAGGTAGAG in the cis-element was shown to be required for the DNA-protein interactions as well as the repression of vIRF promoter activity. Point-mutation analysis identified TTAAT and GTTAATAG as the core sequence motifs for the binding of vR1 and vR2, respectively. These results define the function of a novel transcriptional silencer in the regulation of vIRF gene expression.

Human herpesvirus 8

Human herpesvirus 8 (HHV 8), also known as Kaposi's sarcoma-associated herpesvirus (KSHV) is a g2 herpesvirus and the most recently identified human tumor virus. HHV 8 has been consistently implicated in the pathogenesis of all clinical variants of Kaposi's sarcoma, as well as in the plasma cell variant of multicentric Castleman's disease and primary effusion lymphomas. Pathogenicity of the virus is increased in the host who is immunosuppressed, either iatrogenically or through H1V-1 infection. The HHV 8 genome contains several homologues of cellular genes that regulate cell growth and differentiation, and the exact mechanisms of the virus' oncogenicity using molecular piracy are still being investigated and elucidated. In this article, the authors review the epidemiology, transmission, clinical manifestations, and molecular genetics of HHV 8 infection and provide a summary of the current treatment modalities available to the clinician.

The human herpesvirus-8 (Kaposi's sarcoma-associated herpesvirus) ORF 40/41 region encodes two distinct transcripts

The human herpesvirus-8 (HHV-8) locus encoding ORFs 40/41 is a candidate homologue for the Epstein-Barr virus BBLF 2/3 gene, which encodes the putative primase-associated factor. Northern blot data revealed that two transcripts originated from the HHV-8 ORF 40/41 region. The sizes of these transcripts (2.2 and 0.7 kb) suggested that one transcript was the result of a spliced form of ORFs 40 and 41 and the second transcript originated from a region within ORF 41. cDNA sequence and 5' RACE analysis revealed the removal of an intron between ORFs 40 and 41 and a transcriptional start site 82 nt upstream of ORF 40. The start of transcription for the smaller transcript was mapped to within ORF 41. Regions upstream of the transcriptional start sites were subcloned into a luciferase reporter vector, and transient luciferase assays indicated that distinct promoters drive the expression of each transcript.

The Kaposi's sarcoma-associated herpesvirus latency-associated nuclear antigen binds to specific sequences at the left end of the viral genome through its carboxy-terminus

Latent infection by members of the gammaherpesvirus family is typically characterized by stable episomal maintenance of genomic viral DNA. In the case of Epstein--Barr virus (EBV), this is dependent upon binding of the Epstein-Barr nuclear antigen 1 (EBNA1) to sites which lie within the origin of plasmid replication (OriP). The recently discovered Kaposi's sarcoma-associated herpesvirus (KSHV) encodes the latency-associated nuclear antigen (LANA), which appears to be important for supporting the latent infection of human cells by KSHV. The present work describes site-specific binding of the LANA protein to multiple different elements at the left end of the genome, a region which appears to be critical for maintenance of KSHV episomes. Of the three sites, terminal LANA-binding region 4 (TLBR4) binds LANA with the highest affinity when compared to the other sites. Further characterization of this cis-acting element by mutagenesis studies indicates that the minimal TLBR4-binding sequence is represented by a 13-bp sequence 5prime prime or minute CGCCCGGGCATGG 3prime prime or minute. Furthermore, this specific binding to TLBR4 was mediated by the distal 200 amino acid C-terminus of the LANA protein.

Seroprevalence of Kaposi's sarcoma-associated herpesvirus infection among blood donors from Texas

PURPOSE

Kaposi's sarcoma-associated herpesvirus (KSHV), a gammaherpesvirus recently discovered among AIDS patients with Kaposi's sarcoma, is a potential candidate for screening in blood and plasma donors. While a number of studies have assessed KSHV infection among U.S. blood donors, larger-scale population-based studies would be necessary to develop more refined estimates of the magnitude and variation of KSHV infection across different geographic regions of the U.S. blood supply. The goal of the present study, therefore, was to determine the seroprevalence of KSHV infection and to assess demographic correlates of KSHV infection among south Texas blood donors.

METHODS

KSHV infection was determined using specific serologic assays that measure antibodies to KSHV latent and lytic antigens.

RESULTS

The overall seroprevalence of KSHV in Texas blood donors (15.0%) is substantially higher than previously reported among blood donor and general population samples in the United States. This high rate of KSHV infection persisted across most of the sociodemographic subgroups under study but was particularly elevated among participants with less than a high school education. The infection rate also increased linearly with age.

CONCLUSIONS

The elevated infection rate reported in the present study suggests that screening methods to detect KSHV infection in blood donors should be considered. In view of the etiologic role of KSHV for several malignancies, it would be important for future studies to directly assess the risk of KSHV transmission via blood transfusion.

Prevalence and age distribution of human herpesvirus-8 specific antibodies in Hungarian blood donors

Sera of blood donors were investigated by a peptide ELISA and indirect immunofluorescence assay to assess the prevalence of HHV-8 infection in the Hungarian population. A 14 amino acid long synthetic oligopeptide from the carboxyterminus of orf65/small virus capsid antigen was used as antigen in the ELISA. ELISA results were confirmed by recombinant orf65 antigen Western blot. Antibodies to the latent nuclear antigen were detected by the immunofluorescence assay. Nine of 12 sera obtained from patients with classical Kaposi sarcoma were reactive by ELISA whereas all were positive by immunofluorescence. Four of 482 (0.83%) healthy blood donors had anti-orf65 peptide antibodies and 17/1089 (1.56%) had antibodies to the latent nuclear antigen. In a group of children ages 1-14 years, antibodies to the latent nuclear antigen (0/29) were not detected. The prevalence of antibodies to the latent nuclear antigen showed a moderate but significant increase in correlation with senescence. In the Kaposi sarcoma patients, the titre of antibodies to the latent nuclear antigen was significantly higher than in the healthy seropositive donors. The overall HHV-8 seroprevalence by the two assays was 2.28% (11/482) in the Hungarian blood donor group.

HHV-8 infection in patients with AIDS-related Kaposi's sarcoma in Brazil

The aims of the present study were to determine the prevalence of human herpesvirus type 8 (HHV-8) in HIV-positive Brazilian patients with (HIV+/KS+) and without Kaposi's sarcoma (HIV+/KS-) using PCR and immunofluorescence assays, to assess its association with KS disease, to evaluate the performance of these tests in detecting HHV-8 infection, and to investigate the association between anti-HHV-8 antibody titers, CD4 counts and staging of KS disease. Blood samples from 66 patients, 39 HIV+/KS+ and 27 HIV+/KS-, were analyzed for HHV-8 viremia in peripheral blood mononuclear cells by PCR and HHV-8 antigenemia for latent and lytic infection by immunofluorescence assay. Positive samples for latent nuclear HHV-8 antigen (LNA) antibodies were titrated out from 1/100 to (1/4)09,600 dilution. Clinical information was collected from medical records and risk behavior was assessed through an interview. HHV-8 DNA sequences were detected by PCR in 74.3% of KS+ patients and in 3.7% of KS- patients. Serological assays were similar in detecting anti-LNA antibodies and anti-lytic antigens in sera from KS+ patients (79.5%) and KS- patients (18.5%). HHV-8 was associated with KS whatever the method used, i.e., PCR (odds ratio (OR) = 7.4, 95% confidence interval (CI) = 2.16-25.61) or anti-LNA and anti-lytic antibodies (OR = 17.0, 95%CI = 4.91-59.14). Among KS+ patients, HHV-8 titration levels correlated positively with CD4 counts (rho 0.48, P = 0.02), but not with KS staging. HHV-8 is involved in the development of KS in different geographic areas worldwide, as it is in Brazil, where HHV-8 is more frequent among HIV+ patients. KS severity was associated with immunodeficiency, but no correlation was found between HHV-8 antibody titers and KS staging.

Kaposi's sarcoma before and during a human immunodeficiency virus epidemic in Tanzanian children

BACKGROUND

With the onset of AIDS increased frequency of Kaposi's sarcoma (KS) has been reported. However, there is no case-based comparison of childhood (<14 years) KS before and during the HIV pandemic in sub-Saharan Africa. Here we report on the Tanzanian cancer registry data of pediatric KS in Tanzania and implications with regard to pathogenic factors.

METHODS

One hundred fifty histologically confirmed pediatric KS (PKS) cases registered during 1968 through 1995 (28 years) were analyzed with regard to demographic and clinical characteristics before and during the AIDS epidemic. Statistical analysis was done with the Epi-Info program and chi square test.

RESULTS

Of children with PKS 126 (84%) were male and 24 (16%) were female. The gender ratio was 5.1:1 and 5.4:1 during the endemic and epidemic periods, respectively. The highest occurrence of PKS was observed in the 0- to 5-years age group. Overall 73 (4.9/year) of these cases were registered during the pre and 77 (5.9/year) during the AIDS period. Over time a significant increase in anatomically disseminated KS cases was evident during the AIDS epidemic (P = 0.003).

CONCLUSIONS

These observations indicate that children younger than 5 years are at high risk for developing KS, possibly reflecting low resistance to human herpesvirus (HHV) 8 infection. It is also likely that an increased susceptibility to HHV8 infection and morbidity is related to progressive immunodeficiency. The increase in AIDS PKS incidence appears to reflect a direct or indirect promoting effect of HIV on the development of KS lesions. Recognition of the high KS risk in small children warrants considerations of possible prevention measures including HIV/HHV8 vaccination and therapeutic options.

Epidemiology and pathogenesis of Kaposi's sarcoma-associated herpesvirus

Kaposi's sarcoma (KS) occurs in Europe and the Mediterranean countries (classic KS) and Africa (endemic KS), immunosuppressed patients (iatrogenic or post-transplant KS) and those with acquired immune deficiency syndrome (AIDS), especially among those who acquired human immunodeficiency virus sexually (AIDS-KS). KS-associated herpesvirus (KSHV or HHV-8) is unusual among herpesviruses in having a restricted geographical distribution. Like KS, which it induces in immunosuppressed or elderly people, the virus is prevalent in Africa, in Mediterranean countries, among Jews and Arabs and certain Amerindians. Distinct KSHV genotypes occur in different parts of the world, but have not been identified as having a differential pathogenesis. KSHV is aetiologically linked to three distinct neoplasms: (i) KS, (ii) primary effusion lymphoma, and (iii) plasmablastic multicentric Castleman's disease. The histogenesis, clonality and pathology of the tumours are described, together with the epidemiology and possible modes of transmission of the virus.

Detection of Kaposi sarcoma-associated herpesvirus in bone marrow biopsy samples from patients with multiple myeloma

BACKGROUND

Kaposi sarcoma-associated herpesvirus (KSHV) recently has been identified in the bone marrow (BM) dendritic cell of multiple myeloma (MM) patients. However, whether or not KSHV is associated with MM remains controversial because many studies have failed to detect the presence of KSHV DNA sequences in the BM of their MM patients.

METHODS

We have assayed for KSHV DNA sequences in the BM biopsy samples from 49 patients with MM and from 8 patients with normal BM, using nested polymerase chain reaction and dot blot analysis. The polymerase chain reaction product of KSHV was further determined by single-strand conformation polymorphism and sequence analyses.

RESULTS

KSHV DNA was detectable in 22 of 49 patients (44.9%) with MM but was not detectable in normal BM cells. Single-strand conformation polymorphism and sequence analyses showed that there were interpatient specific mutations. Sixteen out of 22 KSHV DNA sequences belonged to a previously defined subgroup, and the other 6 remain unclassified and may represent distinct strains of KSHV in Taiwan.

CONCLUSIONS

Data strongly supported that KSHV infection did exist in the BM of the current study patients with MM. However, the role of KSHV in the pathogenesis of multiple myeloma remains to be determined.

Close but distinct regions of human herpesvirus 8 latency-associated nuclear antigen 1 are responsible for nuclear targeting and binding to human mitotic chromosomes

Human herpesvirus 8 is associated with all forms of Kaposi's sarcoma, AIDS-associated body cavity-based lymphomas, and some forms of multicentric Castleman's disease. Herpesvirus 8, like other gammaherpesviruses, can establish a latent infection in which viral genomes are stably maintained as multiple episomes. The latent nuclear antigen (LANA or LNAI) may play an essential role in the stable maintenance of latent episomes, notably by interacting concomitantly with the viral genomes and the metaphase chromosomes, thus ensuring an efficient transmission of the neoduplicated episomes to the daughter cells. To identify the regions responsible for its nuclear and subnuclear localization in interphase and mitotic cells, LNAI and various truncated forms were fused to a variant of green fluorescent protein. This enabled their localization and chromosome binding activity to be studied by low-light-level fluorescence microscopy in living HeLa cells. The results demonstrate that nuclear localization of LNAI is due to a unique signal, which maps between amino acids 24 and 30. Interestingly, this nuclear localization signal closely resembles those identified in EBNA1 from Epstein-Barr virus and herpesvirus papio. A region encompassing amino acids 5 to 22 was further proved to mediate the specific interaction of LNA1 with chromatin during interphase and the chromosomes during mitosis. The presence of putative phosphorylation sites in the chromosome binding sites of LNA1 and EBNA1 suggests that their activity may be regulated by specific cellular kinases.

Quantitation of human herpes virus 8 DNA in paraffin-embedded biopsies of HIV-associated and classical Kaposi's sarcoma by PCR

BACKGROUND

Kaposi's sarcoma occurs in patients seropositive and seronegative for the human immunodeficiency virus (HIV) and has been associated with human herpes virus 8 (HHV8). The purpose of this study was to determine and to compare the amount of HHV8 DNA in formalin-fixed tissue sections of Kaposi's sarcoma.

METHODS

From 27 biopsies of Kaposi's sarcoma patients, tissue sections were taken and deparaffinized. Four patients were HIV seronegative and 13 were HIV seropositive. After extraction of DNA copy numbers of HHV8 and beta-globin were determined in every sample by quantitative PCR ELISA using an internal quantitation standard. Results were expressed as HHV8 per beta-globin.

RESULTS

No significant differences were found between biopsies from HIV-positive and HIV-negative patients (14.8+/-19.6 HHV8 per 1000 beta-globin in HIV-positive versus 18.0+/-23.5 in HIV-negative patients).

CONCLUSIONS

These data suggest that HHV8 viral load in Kaposi's sarcoma is relatively low and does not differ in HIV-positive and HIV-negative samples. The importance of viral load determination for prognosis or treatment monitoring remains to be elucidated.

Primary Kaposi sarcoma of the bowel in a HIV-negative patient

A case of Kaposi sarcoma with HIV-negative and sequence of HHV-8 positive and exclusive rectosigmoid and descending colon involvement without immunodeficiency is reported. Histologically, in addition to typical features of Kaposi sarcoma, Cowdry type A inclusions were seen. PCR analysis of the tumor showed positivity for human herpesvirus 8. Two of the six reported cases of Kaposi sarcoma limited to the bowel were from African men before the AIDS epidemic. J. Surg. Oncol. 2001;76:197-200.

Kaposi's sarcoma-associated herpesvirus can productively infect primary human keratinocytes and alter their growth properties

Previous studies have shown the presence of Kaposi's sarcoma-associated herpesvirus (KSHV/HHV8) DNA in endothelial cells, in keratinocytes in the basal layer of the epidermis overlying plaque-stage nodular lesions of cutaneous Kaposi's sarcoma (KS), and in the epithelial cells of eccrine glands within KS lesions. We infected primary cell cultures of human keratinocytes with KSHV/HHV8. At 6 days post infection, transcription of viral genes was detected by reverse transcriptase PCR (RT-PCR), and protein expression was documented by an immunofluorescence assay with an anti-LANA monoclonal antibody. To determine whether the viral lytic cycle was inducible by chemical treatment, KSHV/HHV8-infected keratinocytes were treated with 12-O-tetradecanoylphorbol-13-acetate (TPA) and RT-PCR was performed to confirm the transcription of lytic genes such as open reading frame 26, (which encodes a capsid protein). Finally, to assess infectious viral production, other primary human cells (human umbilical vein endothelial cells), were infected with concentrated supernatant of KSHV-infected, TPA-induced keratinocytes and the presence of viral transcripts was confirmed by RT-PCR. The uninfected keratinocytes senesced 3 to 5 weeks after mock infection, while the KSHV/HHV8-infected keratinocytes continued to proliferate and to date are still in culture. However, 8 weeks after infection, viral genomes were no longer detectable by nested PCR. Although the previously KSHV/HHV8-infected keratinocytes still expressed epithelial markers, they acquired new characteristics such as contact inhibition loss, telomerase activity, anchorage-independent growth, and changes in cytokine production. These results show that KSHV/HHV8, like other herpesviruses, can infect and replicate in epithelial cells in vitro and suggest that in vivo these cells may play a significant role in the establishment of KSHV/HHV8 infection and viral transmission.

Contradictory Concepts in the Etiology and Regression of Kaposi's Sarcoma. The Ferenc Györkey Memorial Lecture

The Introduction is an overview of 3 decades of works performed by Professor Ferenc Györkey (in many cases in collaboration with the author) and aimed at the elucidation of viral participation in the etiology of arteriosclerosis, SLE, hairy cell leukemia, HD, AIDS and KS. Controversial issues surrounding the etiology, treatment and regression of KS are discussed in terms of paracrine and autocrine loops of growth factors; protooncogene-oncogene activations, immunosuppression and retro- and/or herpesviral etiology. In regressing KS lesions the roles played by Fas, Bcl-2, Bax, TNFß; apoptotic-antiapoptotic events; and antiangiogenesis agents especially that of Hu-r-IFNa are elaborated on.