3rd Conference on Retroviruses and Opportunistic Infections Washington, DC - January 28-February 1, 1996

Conf Retroviruses Opportunistic Infect 1996 Jan 28-Feb 1; 3rd:55 (abstract no. 15)

Parravicini C, Capra M, Bestetti G, Aubin JT, Bifulco C, Berti E, Picozza E, Katz E, Briere J, Gessain A, Galli M, Agut H, Corbellino M
Anatomia Patologica, Ospedale Sacco; Malattie Infettive e Clinica Dermatologica, University di Milano.

The histological evolution of Kaposi's Sarcoma (KS) lesions from the early vascular to the late patch and nodular stages is characterized by a progressive increase of spindle cells and involves different types of mesenchymal cells, including endothelial, smooth muscle and monocytic elements. Recently, representational difference analysis allowed the disclosure of unique DNA sequences in KS lesions which were attributed to a novel human herpesvirus suspected to be involved in thepathogenesis of KS and tentatively named KSHV or human herpesvirus-8 (HHV-8). To define the cellular localization of HHV-8 within the lesions, 9 cases of AIDS-associated KS preliminarily screened by liquid-phase PCR (LP-PCR) were examined by in situ hybridization (ISH) and in situ PCR (IS-PCR), using the primer set and probe originally described by Chang et al. (Science 1994, 266: 1865-69). Five LP-PCR negative skin biopsies from AIDS patients without KS and 1 case of AIDS-associated body-cavity-based B-cell lymphoma (BCBL) were taken as negative and positive controls, respectively. By direct ISH a consistent signal was detectable only in the BCBL, where neoplastic cells exhibited a strong nuclear positivity. After IS-PCR an hybridization signal appeared also in KS lesions. Viral positivity by IS-PCR was always restricted to the nucleus and confined within pathologic tissue, where up to 80% of the cells appeared to be infected by HHV-8. By morphology, only KS spindle cells and KS cells lining vascular spaces harbored the virus while intralesional normal blood vessels and extralesional skin tissues were negative. The KS-free cutaneous control biopsies were uniformly negative. Our results are highly suggestive of a direct involvement of HHV-8 in the pathogenesis of KS lesions and demonstrate direct infection by the virus of both LBCB tumoral and KS cells.

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