Human herpesvirus 8 is not detectable in lesions of large plaque parapsoriasis, and in early-stage sporadic, familial, and juvenile cases of mycosis fungoides.

BACKGROUND: Human herpesvirus (HHV) 8, an essential etiologic agent of Kaposi sarcoma, is also associated with several lymphoproliferative disorders. The involvement of HHV 8 in mycosis fungoides (MF) and large plaque parapsoriasis (LPP) is controversial, with contradictory reports from various countries worldwide. OBJECTIVE: We sought to investigate the presence of the HHV 8 genome in skin lesions of LPP and early-stage sporadic, familial, and juvenile MF in patients in Israel. METHODS: Archival paraffin-embedded and frozen samples from skin biopsies of untreated patients with LPP and early-stage MF performed in 1990 through 2006 were randomly collected from the department of dermatology of a tertiary medical center in central Israel. DNA was extracted, and a TaqMan-based real-time polymerase chain reaction assay specific for the K6 gene region was used to detect the HHV 8 genome. RESULTS: A total of 46 biopsies were sampled from 11 patients with LPP and 35 with early-stage MF (17 adults with sporadic MF, 10 children, and 8 patients with familial MF). In all, 44 samples were negative for HHV 8 DNA; two samples from adults with sporadic MF were positive. LIMITATIONS: The presence of HHV 8 antibodies or virus sequences was not assessed in peripheral blood. CONCLUSION: The results of this study, conducted in a region relatively endemic for HHV 8, support most earlier studies showing a lack of association of HHV 8 infection with LPP and sporadic adult-type MF. To our knowledge, the lack of association of HHV 8 infection with juvenile and familial MF has not been previously reported.

Linking the Kaposi's sarcoma-associated herpesvirus (KSHV/HHV-8) to human malignancies.

In 1994, the Kaposi's sarcoma-associated herpesvirus (KSHV/HHV-8) was identified as the etiologic agent of Kaposi's sarcoma (KS). KSHV has since been associated with two additional malignancies: primary effusion lymphoma and multicentric Castleman's disease. In this chapter, we describe the current understanding of the pathogenesis, transmission, and prevalence of KSHV, and its association mainly with KS. We describe evidence demonstrating that KSHV is a causative agent for KS, and we present other factors that possibly contribute to the incidence of KS. We compare worldwide data on the prevalence of KS and of KSHV infection. Specific viral genes that may induce KS tumors or enable their growth also are described. Finally, we discuss the implications of the transmission modes and epidemiology of this virus on recommendations for KSHV screening of tissues and blood products before transplantation or transfusion.

SIAH-1 interacts with the Kaposi's sarcoma-associated herpesvirus-encoded ORF45 protein and promotes its ubiquitylation and proteasomal degradation.

Kaposi's sarcoma-associated herpesvirus (KSHV), also referred to as human herpesvirus 8, is a potentially tumorigenic virus implicated in the etiology of Kaposi's sarcoma, primary effusion lymphoma, and some forms of multicentric Castleman's disease. The open reading frame 45 (ORF45) protein, encoded by the KSHV genome, is capable of inhibiting virus-dependent interferon induction and appears to be essential for both early and late stages of infection. In the present study, we show, both in yeast two-hybrid assays and in mammalian cells, that the ORF45 protein interacts with the cellular ubiquitin E3 ligase family designated seven in absentia homologue (SIAH). We provide evidence that SIAH-1 promotes the degradation of KSHV ORF45 through a RING domain-dependent mechanism and via the ubiquitin-proteasome system. Furthermore, our data indicate the involvement of SIAH-1 in the regulation of the expression of ORF45 in KSHV-infected cells. Since the availability of KSHV ORF45 is expected to influence the course of KSHV infection, our findings identify a novel biological role for SIAH proteins as modulators of virus infection.

Transcriptional regulation of the open reading frame 35 encoded by Kaposi's sarcoma-associated herpesvirus.

Kaposi's sarcoma-associated herpesvirus (KSHV) is a member of the Gammaherpesvirinae and is causally associated with Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman's disease. The KSHV genome encodes over 85 genes; the function of some is entirely unknown. We have characterized the transcriptional regulation of a conserved and uncharacterized Gammaherpesvirinae open reading frame, orf35, which lies in a cluster of several overlapping genes, orf34 to orf38. We identified the transcription start site and analyzed upstream sequences. We found that expression of the KSHV lytic replication and transcription activator (RTA) strongly increased the orf35 promoter activity through a 46-nucleotide region which includes a conserved AP-1 binding site. Electrophoretic mobility shift assay demonstrated direct binding of cJUN and cFOS to the predicted AP-1 binding site. Finally, using a mutated promoter lacking the AP-1 site and dominant-negative cFOS, we established that the RTA-mediated orf35 transactivation is AP-1-dependent.