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Background:  Human herpes virus 8 (HHV-8), a recently discovered human herpes virus is etiologically linked to Kaposi’s sarcoma (KS) as well as to other human neoplasm’s such as pleural effusion lymphoma (PEL) and Castelman disease. Nevertheless, a direct role in tumor formation sustained by virus replication is questioned.

Methods:  We enrolled 60 patients affected by AIDS-related KS in a cross-sectional study in which a blood sample was withdrawn after a complete physical examination. Additional samples from 45 of 60 of the original patients were examined for the follow-up study. Plasma and peripheral blood mononuclear cell (PBMC) HHV-8 loads were measured using a new, highly sensitive, calibrated quantitative real-time PCR assay based on the addition, prior of any sample’s manipulation, of a synthetic DNA calibrator.

Results:  HHV-8 plasma and PBMC loads were detected in 32 of 60 and 27 of 60 patients, respectively. When patients were stratified according to their clinical status, HHV-8 plasma load showed a correlation with the activity and severity of the clinical manifestations. Similar results were obtained when the HHV-8 PBMC load was evaluated, although in 11 individuals the 2 assays were not concordant. Persistent HHV- 8 viremia was demonstrated in sequential samples derived from 6 patients with progressive KS disease, whereas it was consistently undetectable in the samples derived from 21 patients experiencing a complete remission of the disease. The figure below shows the trends of plasma and cellular HHV-8 loads in patients with different clinical outcomes.

Conclusions:  In HIV-positive patients, a direct correlation between HHV-8 replication and the clinical outcome of KS disease has been demonstrated. This finding supports the hypothesis of a direct involvement of HHV-8 replication in KS pathogenesis and lesion dissemination. This observation can have a relevant impact in the clinical management of AIDS-KS patients.

Keywords: HHV-8; Kaposi sarcoma; KS pathogenesis