Human herpesvirus 8 in lymphoma and Kaposi's sarcoma: now the virus can be propagated

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.

Gene transfer of virally encoded chemokine antagonists vMIP-II and MC148 prolongs cardiac allograft survival and inhibits donor-specific immunity

Introducing immunomodulatory molecules into allografts by gene transfer may avoid the side-effects of systemic immunosuppression. vMIP-II and MC148 are two recently identified chemokine homologues encoded by human herpes virus 8 and Molluscum contagiosum, respectively, that have antagonistic activities against multiple different CC and CXC chemokine receptors. We hypothesized that introduction of these molecules into cardiac allografts may block leukocyte infiltration into the grafts and prolong survival. Vascularized and nonvascularized cardiac allografts in mice were performed and plasmid DNA encoding vMIP-II, MC148 and/or vIL-10 was transferred into the allograft at the time of transplantation. Gene transfer of either vMIP-II or MC148 into cardiac allografts markedly prolonged graft survival. Combining gene transfer of either one of these chemokine antagonists with vIL-10 gene transfer, which has a mechanistically different immunosuppressive action, further enhanced graft survival. vMIP-II and MC148 gene transfer both resulted in a marked decrease of donor-specific cytotoxic T lymphocytes (CTL) infiltrating the grafts and inhibited alloantibody production. These results demonstrate that plasmid-mediated gene transfer of virally encoded chemokine antagonists vMIP-II and MC148 can block donor-specific lymphocyte immunity within cardiac allografts and prolong graft survival. This is a new mechanistic approach to analyze, treat, and prevent graft rejection. Delivery of these or related molecules by gene transfer or conventional pharmacologic means may represent a novel therapeutic modality for alloactivation.

HHV8-encoded vMIP-I selectively engages chemokine receptor CCR8. Agonist and antagonist profiles of viral chemokines

Uncertainty regarding viral chemokine function is mirrored by an incomplete knowledge of host chemokine receptor usage by the virally encoded proteins. One such molecule is vMIP-I, a C-C type chemokine of undefined function and binding specificity, encoded by the Kaposi's sarcoma herpesvirus HHV-8. We report here that vMIP-I binds to and induces cytosolic [Ca(2+)] signals in human T cells selectively through CCR8, a CC chemokine receptor associated with Th2 lymphocytes. Furthermore, using a panel of 65 different human, viral, and rodent chemokines, we have established a comprehensive ligand binding "fingerprint" for CCR8. The receptor exhibits marked "high" affinity (K(d) < 15 nM) only for four chemokines, three of them of viral origin: vMIP-I, vMIP-II, vMCC-I, and human I-309. A previously unreported second class of lower affinity ligands includes MCP-3 and possibly two other viral chemokines. vMIP-I and I-309 appear to act as CCR8 agonists: binding to and inducing cytosolic [Ca(2+)] elevation through the receptor. By contrast, vMIP-II and vMCC-I act as potent antagonists: binding without inducing signaling, and blocking the effects of I-309 and vMIP-I. These results suggest a ligand hierarchy for CCR8, identifying vMIP-I as a selective viral chemokine agonist. CCR8 may thus engage a specific subset of chemokines with the potential to regulate each other during viral infection and immune regulation.

Molecular pathological analysis of testicular diffuse large cell lymphomas

The molecular pathology of 20 lymphomas, which presented as testicular masses in patients with no evidence of previous lymphoma, was analyzed. These lymphomas occurred in men with a median age of 69 years (range, 37 to 87 years). Nine of the 14 patients with follow-up died of lymphoma (median survival, 12 months). All cases were diffuse large B-cell lymphomas that were positive for CD20 and commonly showed plasmacytoid differentiation (10 of 20 cases). Three cases were Burkitt's-like large cell lymphomas. Infiltration by lymphoma in the seminiferous tubules was seen in most cases. All lymphomas were negative for human herpesvirus 8 and Epstein-Barr virus by 35 cycles of polymerase chain reaction (PCR), suggesting that these viruses are not involved in the pathogenesis of primary testicular diffuse large B-cell lymphomas (DLBCL). PCR-based studies for t(14;18) and t(11;14) translocations, commonly seen in follicular and mantle-cell lymphomas, were negative in all cases. Nucleotide sequences of the V-D- and J segments of the immunoglobulin heavy chain gene (IgH) rearrangements obtained in 12 cases after PCR amplification were analyzed and compared with known germlines. The frequency of VH-family use in testicular DLBCL was similar to that reported for normal peripheral blood lymphocytes and follicular lymphomas. This contrasts with the previously published findings of preferential use of the VH3- or VH4-family by nodal DLBCL. Comparison with the published germlines showed a low similarity index in most of the cases, suggesting the presence of extensive somatic mutations. Ongoing mutation, as indicated by intraclonal variation in IgH sequence, was observed in all sequenced cases, suggesting direct antigen stimulation, which represents another difference between primary testicular and nodal DLBCL. Our results suggest that testicular lymphomas represent a subset of DLBCL that differs from their nodal counterparts in several respects. Their histological and molecular features show some similarities to those seen in marginal zone (MALT) lymphomas.

Mechanisms of Growth Control of Kaposi's Sarcoma–Associated Herpes Virus–Associated Primary Effusion Lymphoma Cells

Primary effusion lymphoma (PEL) is a distinct clinicopathologic entity associated with Kaposi's sarcoma-associated herpes virus (KSHV). Several cytokines, including interleukin-6 (IL-6), basic fibroblast growth factor (bFGF), and platelet-derived growth factor (PDGF) may be important for survival of KS cells. However, little is known about the interaction of cytokines with KSHV-infected lymphocytes from PEL. Therefore, we investigated what cytokines were produced by KSHV-infected PEL cell lines (KS-1, BC-1, BC-2), what cytokine receptors were expressed by these cells, what response these cells had to selected cytokines, and what was the effect of IL-6 antisense phosphorothioated oligonucleotides. Reverse transcriptase-polymerase chain reaction (RT-PCR) and protein studies showed that these three cell lines produced IL-10, IL-6, and the receptors for IL-6. The granulocyte macrophage colony-stimulating factor (GM-CSF), IL-1β, IL-8, IL-12, bFGF, PDGF, and c-kit transcripts were not detected in the cell lines. High levels (0.7 to 5 ng/mL/106cells/48 hours) of IL-6 protein were consistently detected in supernatants of the cell lines by enzyme-linked immunosorbent assay (ELISA) tests. In clonogenic assays, interferon-α (IFN-α) and IFN-γ suppressed the clonal growth of the PEL cells, but GM-CSF, IL-4, IL-6, IL-8, IL-10, and oncostatin M did not change it. We examined for several autocrine loops that have been suggested to occur in KS. Experiments using antisense oligonucleotides showed that the clonal growth of KS-1 and BC-1 was nearly 100% inhibited by IL-6 antisense oligonucleotides (10 μmol/L), but not at all by either oligonucleotides (≤10 μmol/L) to IL-6 sense, IL-6 scrambled, viral IL-6 (vIL-6) antisense, or IL-10 antisense. Furthermore, the IL-6 antisense oligonucleotides had no effect on two B-cell lymphoma cell lines, which were not infected with KSHV. Addition of IL-6 antibody did not inhibit clonal growth of any of the cell lines. Taken together, we have defined the cytokines and their receptors expressed on PEL cells and have found that these cells synthesized IL-6 and IL-6 receptors; interruption of this pathway by IL-6 antisense oligonucleotides specifically prevented the growth of these cells. These findings will offer potential new therapeutic strategies for PEL.

Mechanisms of Growth Control of Kaposi's Sarcoma–Associated Herpes Virus–Associated Primary Effusion Lymphoma Cells

Primary effusion lymphoma (PEL) is a distinct clinicopathologic entity associated with Kaposi's sarcoma-associated herpes virus (KSHV). Several cytokines, including interleukin-6 (IL-6), basic fibroblast growth factor (bFGF), and platelet-derived growth factor (PDGF) may be important for survival of KS cells. However, little is known about the interaction of cytokines with KSHV-infected lymphocytes from PEL. Therefore, we investigated what cytokines were produced by KSHV-infected PEL cell lines (KS-1, BC-1, BC-2), what cytokine receptors were expressed by these cells, what response these cells had to selected cytokines, and what was the effect of IL-6 antisense phosphorothioated oligonucleotides. Reverse transcriptase-polymerase chain reaction (RT-PCR) and protein studies showed that these three cell lines produced IL-10, IL-6, and the receptors for IL-6. The granulocyte macrophage colony-stimulating factor (GM-CSF), IL-1β, IL-8, IL-12, bFGF, PDGF, and c-kit transcripts were not detected in the cell lines. High levels (0.7 to 5 ng/mL/106cells/48 hours) of IL-6 protein were consistently detected in supernatants of the cell lines by enzyme-linked immunosorbent assay (ELISA) tests. In clonogenic assays, interferon-α (IFN-α) and IFN-γ suppressed the clonal growth of the PEL cells, but GM-CSF, IL-4, IL-6, IL-8, IL-10, and oncostatin M did not change it. We examined for several autocrine loops that have been suggested to occur in KS. Experiments using antisense oligonucleotides showed that the clonal growth of KS-1 and BC-1 was nearly 100% inhibited by IL-6 antisense oligonucleotides (10 μmol/L), but not at all by either oligonucleotides (≤10 μmol/L) to IL-6 sense, IL-6 scrambled, viral IL-6 (vIL-6) antisense, or IL-10 antisense. Furthermore, the IL-6 antisense oligonucleotides had no effect on two B-cell lymphoma cell lines, which were not infected with KSHV. Addition of IL-6 antibody did not inhibit clonal growth of any of the cell lines. Taken together, we have defined the cytokines and their receptors expressed on PEL cells and have found that these cells synthesized IL-6 and IL-6 receptors; interruption of this pathway by IL-6 antisense oligonucleotides specifically prevented the growth of these cells. These findings will offer potential new therapeutic strategies for PEL.

Detection of human herpesvirus-8 DNA in Kaposi's sarcomas from iatrogenically immunosuppressed patients

BACKGROUND

Kaposi's sarcoma (KS) accounts for more than 5% of malignancies in immunosuppressed organ transplant patients (OKS). A new herpesvirus (HHV-8) was identified with high prevalence in biopsy specimens of AIDS-KS, endemic KS, and classic KS and in OKS. KS has also been associated with other underlying diseases in patients treated with corticosteroids, but this subset of KS has been reported to contain HHV-8 in only a few case reports.

OBJECTIVE

In this larger study, we determined the prevalence of HHV-8 in seven patients of Jewish origin in whom KS developed during immunosuppressive therapy for different primary diseases (ISKS).

METHODS

The study included HHV-8 DNA detection by polymerase chain reaction (PCR) coupled with Southern blot and sequence analysis as well as by in situ hybridization.

RESULTS

HHV-8 sequences were detected by PCR with confirmation by Southern blot and sequence analysis in 100% of the ISKS samples. Direct sequencing revealed several previously unknown base changes within the 208 bp region from open reading frame 26 (ORF26[208]) of HHV-8 in ISKS.

CONCLUSION

Ours is the largest known study describing the presence of HHV-8 in iatrogenic KS from immunosuppressed nontransplant patients and provides data of previously unknown sequence variations within the ORF26 of HHV-8 DNA.

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.

A broad-spectrum chemokine antagonist encoded by Kaposi's sarcoma-associated herpesvirus

Kaposi's sarcoma-associated herpesvirus encodes a chemokine called vMIP-II. This protein displayed a broader spectrum of receptor activities than any mammalian chemokine as it bound with high affinity to a number of both CC and CXC chemokine receptors. Binding of vMIP-II, however, was not associated with the normal, rapid mobilization of calcium from intracellular stores; instead, it blocked calcium mobilization induced by endogenous chemokines. In freshly isolated human monocytes the virally encoded vMIP-II acted as a potent and efficient antagonist of chemotaxis induced by chemokines. Because vMIP-II could inhibit cell entry of human immunodeficiency virus (HIV) mediated through CCR3 and CCR5 as well as CXCR4, this protein may serve as a lead for development of broad-spectrum anti-HIV agents.

Kaposi's sarcoma-associated herpesvirus/human herpesvirus-8: a new virus in human pathology

The discovery of a new human herpesvirus in Kaposi's sarcoma (KS) tissue of patients with AIDS has opened up new vistas in virology and oncology. This herpesvirus was first descriptively named KS-associated herpesvirus (KSHV), but was recently renamed human herpesvirus 8 (HHV8). KSHV/HHV8 DNA has been found in all forms of KS, suggesting that it might be involved in the pathogenesis of KS. In addition, KSHV/HHV8 can be detected in both malignant and benign lymphoproliferative disease. KSHV/HHV8 was also found in patients with angiosarcoma of the face and angiolymphoid hyperplasia with eosinophilia. Although only a limited portion of the virus has been sequenced, KSHV/HHV8 is equipped with genes that could confer oncogenic potential. The virus can now be cultured, providing the possibility for studies of viral replication and the mode of transmission. The recently developed serologic assays for antiviral antibodies suggest that infection with KSHV/HHV8 is not ubiquitous because KSHV/HHV8 seropositivity is limited to a small proportion of the population.

Ultrastructural characterization of human herpesvirus 8 (Kaposi's sarcoma-associated herpesvirus) in Kaposi's sarcoma lesions: electron microscopy permits distinction from cytomegalovirus (CMV)

Kaposi's sarcoma (KS) has been shown by molecular techniques to be associated with infection with human herpesvirus 8 (HHV8/KSHV), but specific ultrastructural characterization of the virus has been impaired by the frequent presence in these lesions of other herpesviruses, particularly cytomegalovirus (CMV). Since the ultrastructural appearance of HHV8/KSHV has been studied in the cell line KS-1 uninfected with other viruses including CMV, it was possible to undertake a comparative study of CMV and HHV8/KSHV in KS lesions. HHV8/KSHV was sparsely present and lytic infection was restricted to endothelial cells. The following specific ultrastructural features allowed distinction between HHV8/KSHV and CMV: the viral particles were more delicate and less numerous in cases of HHV8/KSHV infection; the viral tegument was more electron-dense in CMV than in HHV8/KSHV; dense bodies characteristic of CMV were absent in HHV/KSHV; complete CMV viral particles were more variable in size and generally larger (150-200 nm) than HHV8/KSHV (120-150 nm); and finally, the viral envelope was more pleomorphic in CMV than in KSHV/HHV8. Similarities between CMV and HHV8/KSHV included the basic structure of the nucleocapsids and the presence of capsids lacking central DNA cores (so-called non-infectious enveloped particles). These observations show that electron microscopy can be used to identify HHV8/KSHV and confirm the relationship between HHV8/KSHV and KS.

Kaposi's sarcoma-associated herpesvirus infection of bone marrow dendritic cells from multiple myeloma patients

Kaposi's sarcoma-associated herpesvirus (KSHV) was found in the bone marrow dendritic cells of multiple myeloma patients but not in malignant plasma cells or bone marrow dendritic cells from normal individuals or patients with other malignancies. In addition the virus was detected in the bone marrow dendritic cells from two out of eight patients with monoclonal gammopathy of undetermined significance (MGUS), a precursor to myeloma. Viral interleukin-6, the human homolog of which is a growth factor for myeloma, was found to be transcribed in the myeloma bone marrow dendritic cells. KSHV may be required for transformation from MGUS to myeloma and perpetuate the growth of malignant plasma cells.

In situ polymerase chain reaction-based localization studies support role of human herpesvirus-8 as the cause of two AIDS-related neoplasms: Kaposi's sarcoma and body cavity lymphoma

Several lines of investigation point to a new herpesvirus, human herpesvirus-8 (HHV-8), as the cause of two different neoplasms seen in AIDS patients-Kaposi's sarcoma (KS) and body cavity B cell lymphoma. If this virus is the etiological agent, rather than another opportunistic infectious agent, it should be present in the earliest detectable clinical lesions on a temporal basis, and localize to specific target cells in a spatial pattern consistent with tumorigenic pathways. In this study, we take advantage of the clinical accessibility to biopsy early (patch stage) skin lesions of KS to address the temporal issue, combined with in situ PCR and dual immunostaining using a marker identifying malignant cells, to address the spatial localization issue. 21 different tissue samples were subjected to PCR analysis and in situ PCR with and without simultaneous immunostaining. In normal skin from healthy individuals, no HHV-8 DNA was detected by PCR or in situ PCR. However, in all PCR-positive tissues, distinct and specific in situ PCR staining was observed. In four different patch stage KS lesions, in situ PCR staining localized to nuclei of endothelial cells and perivascular spindle-shaped tumor cells. Later stage KS lesions (plaques and nodules) revealed additional positive cells, including epidermal keratinocytes (four of five), and eccrine epithelia (two of four). These patterns were nonrestricted to skin, as pulmonary KS also revealed HHV-8-specific infection of endothelial cells and KS tumor cells, as well as epithelioid pneumocytes (two of two). In body cavity B cell lymphoma by dual staining, HHV-8 was present in malignant tumor cells (EMA immunostained positive) and not in reactive lymphocytes. These results reveal an early temporal onset and nonrandom tissue and cellular distribution pattern for HHV-8 infection that is consistent with a causal link between this DNA virus and two AIDS-related neoplasms.

Epidemiology of HIV-related oral manifestations in women: a review

OBJECTIVE

(1) To assess the extent of knowledge acquired since 1981 on the epidemiology of HIV-related oral manifestations in women; (2) to determine if these findings differ by gender; and (3) to assess the needs and direction for future epidemiologic research on oral disease and HIV infection in women in relation to men.

DATA IDENTIFICATION

A computer-assisted search was conducted to identify epidemiologic studies reporting the frequency of various oral conditions in HIV-infected women. Studies on periodontal disease as manifestation of HIV infection were not included.

DATA EXTRACTION

Methods used in the retrieved articles were reviewed with respect to target population, study design, sampling scheme, outcomes, measurements and statistical issues. Results were summarized in relation to oral findings in HIV-infected men.

RESULTS OF DATA SYNTHESIS

Most studies were prospective, and sample selection was non-random. Studies differed with respect to geographic location, risk category for HIV transmission, and stage of HIV disease. Despite these differences, oral lesions were found in at least 15% of HIV-infected women, and the most common oral lesion in all studies was candidiasis. Women differed from men with respect to the prevalence of hairy leukoplakia and Kaposi's sarcoma (KS) both of which were significantly less common in women.

CONCLUSION

Future epidemiologic studies should be directed at identifying cofactors involved in addition to Epstein-Barr virus (EBV) in the development of hairy leukoplakia, and in addition to KS herpes virus (KSHV) in the occurrence of KS.

Kaposi's sarcoma-associated herpesvirus-like DNA sequences (KSHV/HHV-8) in oral AIDS-Kaposi's sarcoma: a PCR and clinicopathologic study

Recently, a new human herpesvirus (KSHV/HHV-8) has been identified in classic, transplant, endemic, and AIDS Kaposi's sarcoma that may be involved in the pathogenesis of Kaposi's sarcoma. The purpose of this study was to evaluate oral AIDS-Kaposi's sarcoma for detection of KSHV/HHV-8 DNA. DNA extracted from 54 oral AIDS-Kaposi's sarcoma lesions (47 initial, 7 postvinblastine treated), 5 non-Kaposi's sarcoma HIV-positive lesions, and 3 non-Kaposi's sarcoma HIV-negative lesions was evaluated by polymerase chain reaction (KS330(233bp)amplicon) for KSHV/HHV-8. The AIDS-Kaposi's sarcoma study population consisted of 52 patients (51:1, men:woman; 92% men having sex with men, 8% heterosexual; mean age, 38 years; mean, CD4 59/mm3) Opportunistic infections occurred in 88% (candidiasis, 65%; Pneumocystis carinii pneumonia, 31%; nonoral Kaposi's sarcoma, 25%; mycobacterium avium-intracellulare (MAI), 16%; cytomegalovirus, 14%; herpes simplex virus, 14%). Sexually transmitted diseases occurred in 73% (gonorrhea, 37%; syphilis, 23%; condyloma, 22%; HSV, 16%). Most frequent lesion sites were palate (74%) and gingiva (17%). Most common lesion types were purple nodular (48%) and macular (42%). Histopathologic subtypes were nodular (71%), plaque (27%), and patch (2%). Polymerase chain reaction analysis detected KSHV/HHV-8 DNA in 53 of 54 AIDS-Kaposi's sarcoma lesions (47 of 47 initial, 6 of 7 postvinblastine treatment). KSHV/HHV-8 DNA was not detected in non-Kaposi's sarcoma lesions in HIV-positive or HIV-negative persons. KSHV/HHV-8 DNA sequence is present in a high proportion of oral AIDS-Kaposi's sarcoma lesions. Whether KSHV/HHV-8 is an etiologic agent or a cofactor in the development of this vascular neoplasm is uncertain and remains to be proven. Polymerase chain reaction analysis for KSHV/HHV-8 DNA sequence detection may be helpful in identifying Kaposi's sarcoma in early vascular proliferations, when the characteristic histopathologic features are not present.

Molecular mimicry of human cytokine and cytokine response pathway genes by KSHV

Four virus proteins similar to two human macrophage inflammatory protein (MIP) chemokines, interleukin-6 (IL-6), and interferon regulatory factor (IRF) are encoded by the Kaposi's sarcoma-associated herpesvirus (KSHV) genome. vIL-6 was functional in B9 proliferation assays and primarily expressed in KSHV-infected hematopoietic cells rather than KS lesions. HIV-1 transmission studies showed that vMIP-I is similar to human MIP chemokines in its ability to inhibit replication of HIV-1 strains dependent on the CCR5 co-receptor. These viral genes may form part of the response to host defenses contributing to virus-induced neoplasia and may have relevance to KSHV and HIV-I interactions.

KSHV antibodies among Americans, Italians and Ugandans with and without Kaposi's sarcoma

A major controversy regarding Kaposi's sarcoma-associated herpesvirus (KSHV or HHV8) is whether or not it is a ubiquitous infection of humans. Immunoassays based on KSHV- and Epstein-Barr virus (EBV)-coinfected cell lines show that most US AIDS-KS patients have specific antibodies to KSHV-related antigens. We have developed a sensitive indirect immunofluorescence assay (IFA) based on an EBV-negative, KSHV-infected cell line, BCP-1. When we used this IFA assay, KSHV-related antibodies were found in 71-88% of serum samples from US, Italian and Ugandan AIDS-KS patients, as well as all serum samples examined from HIV-seronegative KS patients. Although none of the US blood donors examined were KSHV seropositive by IFA, intermediate and high seroprevalence rates were found in Italian and Ugandan control populations. Antibody kinetics showed that more than half of the AIDS-KS patients who were examined IgG-seroconverted before KS development, and antibody levels did not decline after seroconversion. For these patients, seropositivity rates increased linearly with time, suggesting that the rate of infection was constant and that the risk of developing KS once infected with KSHV is not highly dependent on the duration of infection. These data strongly suggest that KSHV is not ubiquitous in most populations and that the virus may be under strict immunologic control in healthy KSHV-infected persons.

Radiation treatment of oral epidemic Kaposi's sarcoma lesions: potential adverse effects

Epidemic Kaposi's sarcoma, which has consistently been the most prevalent malignancy in people with HIV disease, frequently presents with lesions in the oral cavity. Guidelines for treating oropharyngeal lesions with radiotherapy are ubiquitous in the literature. Treatment indications include pain, dysphagia, and obstruction. Radiotherapy dosage and fractionation differ from that prescribed for non HIV-infected people. Current literature reveals better treatment outcomes for people infected with HIV if treatment is managed by practitioners experienced in HIV care. This article presents a review of the literature and a case study of a HIV-infected patient who experienced severe adverse effects of irradiation.

Novel human herpesviruses (human herpesviruses 6, 7 and 8)

The number of members in the family Herpesviridae has increased in the last 10 years due to the description of three novel human herpesviruses: human herpesvirus 6 (HHV-6) in 1986, human herpesvirus 7 (HHV-7) in 1990, and human herpesvirus 8 (HHV-8), also known as Kaposi's sarcoma-associated herpesvirus (KSHV), in 1994. HHV-6 and HHV-7 were first isolated from blood lymphocyte cultures, while HHV-8 was identified following a specific molecular biology approach in the search for the etiologic agent of Kaposi's sarcoma. The three viruses are lymphotropic, T-cells being the targets of HHV-6 and HHV-7, and B-cells being probably those of HHV-8. The ability to be propagated in cell cultures in vitro differs according to the virus concerned: this can be done readily with HHV-6, with more difficulties in the case of HHV-7, and has not yet been achieved in the case of HHV-8. Human infection with HHV-6 and HHV-7 is ubiquitous, widespread and acquired early in life. HHV-8 epidemiology is still unclear, and there are two hypotheses: a restricted dissemination in the general population like herpes simplex virus type 2, or a widespread infection like all other human herpesviruses. The polymerase chain reaction is the common method for the detection of infection using specific primers and probes for HHV-6, HHV-7 and HHV-8 respectively. Serologic assays are only available for HHV-6 and HHV-7, with limitations being due, in particular, to possible cross-reactions with cytomegalovirus. HHV-6 is the causative agent of exanthem subitum (sixth disease). Its role as an opportunistic agent and immune dysfunction inducer is debated and currently under investigation. The pathogenic role of HHV-7 seems to be modest, with one case of exanthem subitum reported so far. HHV-8 is strongly associated with three diseases: Kaposi's sarcoma, Castleman's disease and body-cavity-based lymphomas. The therapy against these novel viruses has to be considered in the future.