Restricted tissue distribution of extralesional Kaposi's sarcoma-associated herpesvirus-like DNA sequences in AIDS patients with Kaposi's sarcoma

Specific herpesvirus-like DNA sequences have been found in Kaposi's sarcoma (KS) lesions of AIDS patients, suggesting that a novel gamma herpesvirus, homologous to Epstein-Barr virus and herpesvirus saimiri, could be implicated in the pathogenesis of KS. To better understand the role of this putative etiological agent, named Kaposi's sarcoma-associated herpesvirus (KSHV) or human herpesvirus 8 (HHV-8), we investigated by the polymerase chain reaction (PCR) the presence of viral DNA sequences in various organs obtained at autopsy from seven AIDS patients with KS and six without KS. For each sample, to exclude positive results due to visceral KS dissemination, the presence of microscopic foci of KS cells was rules out by histology and CD34 immunohistochemistry on serial frozen sections immediately adjacent to those employed for DNA extraction. PCR and nested PCR were performed with primers specific for the HIV-8 330 Bam fragment originally described by Chang et al. (Science 1994;266:1865-1869). As quality control, the extracted DNA was amplified with primers for human beta-globin. All KS legions were HHV-8 positive. In addition, extralesional KSHV DNA sequences were detected in seven of seven lymphoid organs and in five of five prostate glands of KS patients. Normal skin was positive in three of five cases and bone marrow in two of three tested cases, all other tissues being negative by PCR and nested PCR. By contrast, no virus was detected in tissue samples of AIDS cases without KS. The restricted organ distribution here documented argues for a selective tissue tropism of HHV-8 in vivo in AIDS patients and suggests that in the infected host lymphoid organs and the prostate gland may represent privileged sites of viral latency and persistence.