Herpesvirus-like nucleic acid sequences in patients with Eastern European sporadic Kaposi's Sarcoma

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.

Detection of herpesvirus DNA in peripheral blood mononuclear cells and skin lesions of patients with pemphigus by polymerase chain reaction

Pemphigus is an autoimmune disease where both endogenous (genetic) and exogenous (environmental) factors play a part. Viral infections, in particular herpesvirus infections, have been identified as a possible triggering factor for pemphigus. In this study, using the polymerase chain reaction, we studied peripheral blood mononuclear cells (PBMC) and skin biopsies from patients with pemphigus, and in some of these were able to demonstrate the presence of DNA sequences of herpes simplex virus 1/2 (50% in PBMC and 71% in skin biopsies), Epstein-Barr virus (15% in PBMC and 5% in skin biopsies) and human herpesvirus 6 (20% in PBMC only). However, the inability to detect herpesvirus DNA consistently in these cases suggests that viral infection may only be an occasional factor triggering the outbreak or exacerbation of the disease. The possible role of interferons and interleukins in the pathogenesis of virus-induced pemphigus is discussed.

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.

Progressive HHV-8-positive classic Kaposi's sarcoma: rapid response to interferon alpha-2a but persistence of HHV-8 DNA sequences in lesional skin

The pathogenesis of Kaposi's sarcoma (KS) is often attributed to an infectious agent. In particular, the human herpesvirus 8 (HHV-8) was currently shown to be closely related to all known KS types, including HIV-associated KS, European classic KS, African endemic KS and iatrogenic KS. We report here on an HIV-negative, German patient of neither Jewish nor Mediterranean descent with disseminated classic KS showing unusual rapid progression into the tumour stage. After systemic administration of interferon alpha-2a over 4 weeks all tumour lesions cleared completely. Interestingly, HHV-8 DNA sequences detected by nested polymerase chain reaction in KS lesions before the onset of treatment were still present in lesional skin after complete remission of the tumour. No recurrence was seen after a follow-up period of 6 months.

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.

Lack of evidence of human herpesvirus 8 DNA sequences in HIV-negative patients with various lymphoproliferative disorders of the skin

Human herpesvirus 8 (HHV-8) is a new virus which has been reported in Kaposi's sarcoma and some lymphoproliferative disorders such as Castleman's disease and body-cavity-based lymphoma. Because HHV-8 shares homology with Epstein-Barr virus (EBV), we searched for the presence of HHV-8 DNA sequences in various cutaneous T- and B-cell lymphoma by the polymerase chain reaction (PCR). Forty-seven HIV-negative patients with cutaneous lymphoma or large plaque parapsoriasis were enrolled in the study. For the detection of HHV-8 DNA sequences we used PCR followed by a hybridization with a digoxigenin-labelled probe and nested-PCR. HHV-8 DNA sequences could only be detected in a patient with large plaque parapsoriasis. Our study does not suggest any direct implication of HHV-8 in the pathogenesis of most cutaneous lymphoma. Serological studies will be helpful to appreciate if there is an epidemiological link between HHV-8 and cutaneous lymphomas.

Search for Kaposi's sarcoma-associated virus DNA in hemangioproliferative disorders and cutaneous malignant lymphoma

Recently, a Kaposi's sarcoma-associated herpesvirus (KSHV) was discovered. We evaluated by PCR 14 paraffin-embedded specimens with the histological diagnosis of endemic, classic and HIV-associated Kaposi's sarcoma (KS) for the presence of the KSHV DNA sequence. In addition, biopsies of adjacent, histologically unaffected skin, peripheral-blood mononuclear cells (PBMCs) of HIV-infected KS patients, PBMCs of one classic KS patient, and specimens of patients with hemangioproliferative disorders other than KS as well as samples of cutaneous T- and B-cell lymphoma were analyzed for KSHV. In all cases of KS, independent of the KS subtype, KSHV was detected in lesional skin. No KSHV was found in biopsies of the adjacent unaffected skin or PBMCs of HIV-infected KS patients. We found KSHV in the PBMCs of a patient with classical KS. All specimens of cutaneous T- and B-cell lymphomas or lymphomatoid papulosis were negative for KSHV. In addition, the samples with hemangioproliferative disorders other than KS were negative for KSHV. There was one borderline case of KS or acroangiodermatitis that was positive for KSHV. Additional histological sections and clinical evaluation confirmed the diagnosis of classic KS. In summary, the data indicate that PCR for KSHV should be a useful diagnostic tool in cases of hemangioproliferative disorders.

Strain variability among Kaposi sarcoma-associated herpesvirus (human herpesvirus 8) genomes: evidence that a large cohort of United States AIDS patients may have been infected by a single common isolate

Previous analysis of the majority of Kaposi's sarcoma (KS) tumors, in both AIDS and non-AIDS populations, has revealed the consistent presence of two small subsegments (open reading frame 25/26 [ORF25/26] and ORF75) of a novel human gamma class herpesvirus genome referred to as KSHV or HHV-8. We have carried out DNA sequence comparisons with DNAs encompassing a total of 2,500 bp each over three separate PCR-amplified fragments from KS lesions and body cavity-based lymphoma (BCBL) samples from 12 distinct patients, including four African and two classical or endemic non-AIDS KS samples. The results revealed differences at 37 of 2,500 nucleotide positions (i.e., 1.5% overall variation). However, the 12 HHV-8 genomes examined fell into three distinct but very narrow subgroupings (A, B, and C strains). All A strain isolates differed from B strain isolates at 16 positions, but of the eight U.S. samples tested, six were A strains, and these differed at no more than two positions among them. Similarly, three of the four African samples were B strains, which differed from each other at only one position. The two C strain genomes also displayed only one nucleotide variation, but they differed from all A strains at 26 positions and from all B strains at 20 positions. One C strain genome was present in all six independent lesions from an AIDS KS patient with disseminated disease, and the other represented a mosaic A/C recombinant genome from the HBL6 cell line derived from a BCBL tumor. Evaluation of previous data suggests that B and C strains may predominate in Africa and that A strains predominate in classical Mediterranean samples. Although both B and C strains are represented in U.S. AIDS patients, the majority (70 to 80%) of samples from the mid-East Coast region at least appear to be virtually identical, supporting the concept that they may all derive from the spread during the AIDS epidemic of a single recently transmitted infectious agent.