IDENTIFICATION OF HHV8 IN EARLY KAPOSIS-SARCOMA - IMPLICATIONS FOR KAPOSIS-SARCOMA PATHOGENESIS

Aims-Kaposi's sarcoma is a vascular tumour of uncertain pathogenesis p ossibly caused by an infectious agent, identified in high risk groups. Accumulating solution phase polymerase chain reaction (PCR) and seroe pidemiological data suggest that a previously undescribed herpes DNA v irus (human herpesvirus 8 (HHV8)) is the causative agent, Using a uniq ue cohort of early Kaposi's sarcoma, the precise cell type infected wi th HHV8 in such lesions was identified to elucidate further the role o f HHV8 in the pathobiology of Kaposi's sarcoma. Methods-Sixteen cases of early Kaposi's sarcoma (derived from skin and lymph node) were asse ssed for the presence of HHV8 using both standard solution phase PCR a nd TaqMan PCR to the KS330 Bam region of HHV8. In situ amplification w as also performed on a selected group in an attempt to identify the ca ndidate infected cells. Results-Using both conventional solution phase and TaqMan PCR, 87% of cases were positive. In addition, HHV8 amplico ns were localised in situ to endothelial and spindle cell proliferatio ns in early Kaposi's sarcoma. The HHV8 viral load varied from lesion t o lesion. Conclusions-The presence of HHV8 in early lesions supports a role for HHV8 in the pathogenesis of Kaposi's sarcoma. Coupled with r ecent seroepidemiological studies, these results suggest that HHV8 is the aetiological agent of Kaposi's sarcoma. Its precise interaction wi th other factors known to be involved in the development of Kaposi's s arcoma, including cytokines and anti-apoptosis genes, requires elucida tion.