Lack of evidence of an association between HHV-8 and multiple myeloma

Joint Nordic prospective study on human herpesvirus 8 and multiple myeloma risk

An association between human herpesvirus 8 (HHV8) and multiple myeloma (MM) has been reported, though most studies have not confirmed such association. To follow-up on a previous prospective seroepidemiological study, where HHV8 tended to associate with MM risk, we linked five large serum banks in the Nordic countries with the Nordic cancer registries and 329 prospectively occurring cases of MM were identified, together with 1631 control subjects matched by age and gender. The HHV8 seroprevalences among cases and controls were similar (12 and 15%, respectively) and HHV8 seropositivity did not associate with the risk of MM, neither when considering positivity for lytic antibodies (relative risk (RR)=0.8, 95% confidence interval (CI)=0.5–1.1) nor for latent antibodies (RR=0.6, 95% CI=0.1–2.7). Similar risks were seen when analysis was restricted to case–control sets with at least 2 years lag before diagnosis (RR=0.8, 95% CI=0.5–1.2 and RR=0.9, 95% CI=0.1–4.2). In conclusion, the data indicate that HHV8 infection is not associated with MM.

Pathogenesis of Kaposi's sarcoma

Kaposi's sarcoma (KS) is a disease characterized by proliferative vascular lesions, which almost invariably contain the KS-associated herpesvirus (KSHV), also called human herpesvirus 8. KSHV is a lymphotrophic and angiotrophic herpesvirus, whose genome encodes several proteins involved in proliferation, antiapoptotic functions, and inflammation. Most KS spindle cells express latent KSHV genes, but a few express lytic genes, which might be involved in angiogenic and paracrine mechanisms that contribute to KS pathogenesis. A number of tissue culture and mouse models have been established, but a comprehensive system that accurately portrays KS pathogenesis still does not exist.

Spectrum of Kaposi's sarcoma-associated herpesvirus, or human herpesvirus 8, diseases

Human herpesvirus 8 (HHV-8), also known as Kaposi's sarcoma-associated herpesvirus (KSHV), discovered in 1994, is a human rhadinovirus (gamma-2 herpesvirus). Unlike other human herpesviruses (herpes simplex virus, Epstein-Barr virus, varicella-zoster virus, cytomegalovirus, HHV-6, and HHV-7), it is not widespread in the general population and has many unique proteins. HHV-8 is strongly associated with all subtypes of Kaposi's sarcoma (KS), multicentric Castleman's disease, and a rare form of B-cell lymphoma, primary effusion lymphoma. In addition, HHV-8 DNA sequences have been found in association with other diseases, but the role of the virus in these diseases is largely unconfirmed and remains controversial. The seroprevalence of HHV-8, based on detection of latent and lytic proteins, is 2 to 5% in healthy donors except in certain geographic areas where the virus is endemic, 80 to 95% in classic KS patients, and 40 to 50% in HIV-1 patients without KS. This virus can be transmitted both sexually and through body fluids (e.g., saliva and blood). HHV-8 is a transforming virus, as evidenced by its presence in human malignancies, by the in vitro transforming properties of several of its viral genes, and by its ability to transform some primary cells in culture. It is not, however, sufficient for transformation, and other cofactors such as immunosuppressive cytokines are involved in the development of HHV-8-associated malignancies. In this article, we review the biology, molecular virology, epidemiology, transmission, detection methods, pathogenesis, and antiviral therapy of this newly discovered human herpesvirus.

Frequent demonstration of human herpesvirus 8 (HHV-8) in bone marrow biopsy samples from Turkish patients with multiple myeloma (MM)

In order to investigate the frequency of HHV-8 in MM patients from another geographic location, we obtained fresh bone marrow (BM) biopsies from Turkish patients with MM (n = 21), monoclonal gammopathy of undetermined significance (MGUS) (n = 2), plasmacytoma (n = 1) with BM plasma cell infiltration, various hematological disorders (n = 6), and five healthy Turkish controls. The frequency of HHV-8 was analyzed by polymerase chain reaction (PCR) in two independent laboratories in the USA and in Turkey. Using fresh BM biopsies, 17/21 MM patients were positive for HHV-8 whereas all five healthy controls, and six patients with other hematological disorders were negative. Two patients with MGUS, and one patient with a solitary plasmacytoma were also negative. The data from the two laboratories were completely concordant. Also using primer pairs for v IRF and v IL-8R confirmed the results observed with the KS330233 primers. Furthermore, sequence analysis demonstrated a C3 strain pattern in the ORF26 region which was also found in MM patients from the US. Thus, HHV-8 is present in the majority of Turkish MM patients, and the absence of the virus in healthy controls further supports its role in the pathogenesis of MM.

A prospective seroepidemiological study of human herpesvirus-8 infection and the risk of multiple myeloma

Presence of the Human Herpesvirus 8 (HHV8) genome has been reported in the bone marrow of multiple myeloma (MM) patients. So far, serological studies of HHV8 and MM have been inconsistent but have not included prospective epidemiological studies. We evaluated whether HHV8 infection is associated with increased risk for MM in a prospective population-based study of 39 000 Finnish subjects who donated serum samples in the period 1968-72. Serum samples from 47 subjects who developed MM during a 23-year follow-up and 224 age, area of residence and sex-matched subjects who remained healthy over a similar follow-up period were evaluated for HHV8 antibodies at enrollment, as assayed both with an immunofluorescence assay (IFA) for lytic and latent HHV8 antigens and by Western blot (WB) with three recombinant HHV8 proteins (ORFs 65, 73 and K8.1A). HHV8 seropositivity for at least one HHV8 protein on WB was found in 7% of the Finnish population and was not associated with the risk of developing MM (Relative Risk (RR) = 0.89, Confidence Interval (CI): 0.25-3.25). HHV8 seropositivity for lytic and latent antigens in the IFA was found in 16% and 0.4% of the Finnish population and tended to associate with risk of MM (RR = 2.02, CI: 0.94-4.33 and RR = 10.00, CI: 0.91-110.29, respectively). In conclusion, no statistically significant evidence for an association between HHV8 infection and the risk of future MM was found.

Human herpesvirus 8 (KSHV) contamination of peripheral blood and autograft products from multiple myeloma patients

Human herpesvirus 8 (HHV-8), also known as Kaposi's sarcoma-associated herpesvirus (KSHV), has recently been identified within the bone marrow dendritic cells of multiple myeloma (MM) patients. This virus contains homologues to human cytokines such as IL-6 that could potentially stimulate myeloma cell growth and contribute to disease pathogenesis. Since mobilization chemotherapy may increase circulating dendritic cell numbers, we searched for HHV-8 in peripheral blood mononuclear cells (PBMCs) before and after mobilization chemotherapy given to MM patients. Furthermore, we determined if autograft purging using the CEPRATE SC device would reduce the percentage of HHV-8 infected stem cell products. Only two of the 39 PBMC samples collected prior to mobilization chemotherapy contained PCR detectable virus, yet nine of 37 PBMCs collected on the first day of leukapheresis had detectable HHV-8 (P = 0.016). HHV-8 was more frequently identified in autograft products before vs after Ceprate SC selection (40% vs 15%, P = 0.016). Although the role HHV-8 plays in myeloma pathogenesis remains unclear, these results imply that mobilization chemotherapy increases the numbers of circulating HHV-8-infected dendritic cells within the peripheral blood. In addition, CD34 selection of autograft products in MM patients may reduce the reintroduction of virally infected cells following high-dose chemotherapy. Bone Marrow Transplantation (2000) 25, 153-160.

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), has 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, a rare type of malignant lymphoma which possesses an unusual set of clinical and biologic features, suggesting that they represent 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, where it has been identified in bone marrow adherent cells but not in the neoplastic myeloma plasma cell population. However, the latter finding remains controversial. The discovery of KSHV in a subset of malignant lymphomas has allowed the development of lymphoma cell lines which now serve as biological reagents for propagating the virus, as a substrate for serologic assays, and as a model system for pathobiologic studies. This review discusses the features of KSHV-associated lymphoproliferative disorders and the evidence supporting its role in the pathogenesis of these diseases.