PROPAGATION OF A HUMAN HERPESVIRUS FROM AIDS-ASSOCIATED KAPOSIS-SARCOMA

Background Although unique DNA sequences related to gammaherpesviruses have been found in Kaposi's sarcoma lesions, it is uncertain whether this DNA encodes a virus that is able to reproduce. Methods We isolate d and propagated a filterable agent whose DNA sequences were found to be identical to those of the Kaposi's sarcoma-associated herpesvirus ( KSHV). We obtained early-passage spindle cells from skin lesions of pa tients with the acquired immunodeficiency syndrome (AIDS) who had Kapo si's sarcoma and cultured them with cells of the human embryonal-kidne y epithelial-cell line 293. We characterized the virus according to it s effects on cellular morphology and viral replication and its appeara nce on electron microscopy. Results KSHV was cytotoxic to 293 cells an d was detected by the polymerase chain reaction (PCR) in infected cell s but not uninfected ones. Cytotoxicity and positive PCR signals were consistently maintained with viral titers of 1 million per milliliter or higher for about 20 serial infections of 293 cells. The viral copy number was relatively low (1 to 10 copies per cell). Viral replication was confirmed by Southern blot analysis of DNA isolated from the enri ched nuclear fraction of infected cells and by a semiquantitative PCR using dilutions of the lysates of infected cells to detect the 233-bp viral DNA fragment originally described in association with Kaposi's l esions. Electron microscopy revealed herpesvirus-like particles in abo ut 1 percent of cells from infected cultures, as compared with none in cells from uninfected cultures. Conclusions A herpesvirus with DNA se quences identical to those of KSHV can be propagated from skin lesions of patients with AIDS-associated Kaposi's sarcoma. (C) 1997, Massachu setts Medical Society.