Experimental transmission of Kaposi's sarcoma-associated herpesvirus (KSHV/HHV-8) to SIV-positive and SIV-negative rhesus macaques

Kaposi's sarcoma-associated herpesvirus (KSHV) is a gamma-herpesvirus associated with Kaposi's sarcoma (KS) and two lymphoproliferative diseases, primary effusion lymphoma (PEL) and multicentric Castleman's disease. Studies on the biology and pathogenesis of KSHV have been limited by lack of efficient cell culture systems and lack of a suitable animal model for KS. Here we report on the experimental inoculation of SIV-positive and SIV-negative rhesus macaques with KSHV-infected PEL cells or KSHV preparations derived from PEL cells. Low levels of viral DNA could be detected in cultivated peripheral blood mononuclear cell of all animals, as well as in the bone marrow of one monkey that died from SAIDS. However, we were not able to detect KSHV-specific antibodies or transcripts, nor did we observe any symptoms clearly related to KSHV infection (e.g. KS or lympho-proliferative disease). Hence, although KSHV replicates in rhesus macaques at very low levels, this non-human primate host is unlikely to provide a useful animal model for disease.

Definition of an optimal cytotoxic T lymphocyte epitope in the latently expressed Kaposi's sarcoma-associated herpesvirus kaposin protein

Cytotoxic T lymphocytes (CTL) recognize and kill virus-infected cells and contribute to immunologic control of viral replication. For many herpesviruses (e.g., Epstein-Barr and cytomegalovirus), virus-specific CTL responses can be readily detected in infected persons, but CTL responses against Kaposi's sarcoma-associated herpesvirus (KSHV) appear to be weak and remain poorly characterized. Using a human leukocyte antigen (HLA) binding motif-based epitope prediction algorithm, we identified 37 HLA-A*0201 binding peptides from 8 KSHV open-reading frames (ORFs). After in vitro stimulation of peripheral blood mononuclear cells from KSHV-infected persons, CTL responses against 1 peptide in the KSHV kaposin protein (ORF K12) were detected in 2 HLA-A*0201-positive subjects. The optimal CTL epitope was identified by HLA restriction analysis and peptide titration assays. These data describe a latent phase viral gene product targeted by CTL that may be relevant for KSHV immunopathogenesis.

Evidence for concurrent epidemics of human herpesvirus 8 and human immunodeficiency virus type 1 in US homosexual men: rates, risk factors, and relationship to Kaposi's sarcoma

We examined human herpesvirus 8 (HHV-8) seroprevalence and seroincidence among 245 homosexual men from New York City (NYC) and Washington, DC (DC) who have been followed since 1982. An immunofluorescence assay measured antibodies to a latent HHV-8 nuclear antigen. Seroprevalence was 20.4% in 1982; seroincidence was approximately 15%/year during 1982-1983 but fell sharply thereafter. NYC men had a higher seroprevalence (odds ratio, 3.43; P<.001) and seroincidence (rate ratio, 2.13; P=.01) than DC men. Risk of Kaposi's sarcoma (KS) was increased in seropositive men (adjusted relative hazard, 3.58; P=.02). Among men who were seropositive for both human immunodeficiency virus type 1 and HHV-8, the 10-year cumulative risk of KS was 39%; time from coinfection to KS diagnosis ranged from 15 to 154 months (median, 63.5 months). This study shows an epidemic of HHV-8 among US homosexual men in the early 1980s that was associated with a high risk of developing KS.

Lytic growth of Kaposi's sarcoma-associated herpesvirus (human herpesvirus 8) in culture

Kaposi's sarcoma (KS) is the leading neoplasm of AIDS patients, and HIV infection is known to be a major risk factor for its development. However, KS can occur in the absence of HIV infection and the risk of KS development varies widely even among HIV-infected patients, with homosexual men with AIDS being 20 times more likely to develop KS than AIDS-afflicted children or hemophiliacs. These and other data strongly suggest that a sexually transmitted agent or co-factor may be involved in KS pathogenesis. Recently, DNA sequences corresponding to the genome of a novel member of the herpesvirus family have been identified within AIDS-KS biopsies, and several reports indicate that these sequences are also present in all forms of HIV-negative KS. These and other findings suggest this new agent, referred to as KS-associated herpesvirus (KSHV) or human herpesvirus 8 (HHV8), as a candidate for the putative etiologic cofactor. However, the role of this agent in KS remains hotly debated. Further progress in understanding its biology has been severely hampered by the lack of a cell culture system for virus growth. Here we report the development of a system for the lytic growth of this virus in a latently infected B cell line and present the first ultrastructural visualization of the virus. This system will facilitate the detailed study of the molecular biology of viral replication, the testing of antiviral drugs and the development of diagnostic tests for viral infection.