LYTIC GROWTH OF KAPOSIS SARCOMA-ASSOCIATED HERPESVIRUS (HUMAN HERPESVIRUS-8) IN CULTURE

Kaposi's sarcoma (KS) is the leading neoplasm of AIDS patients, and HI V infection is known to be a major risk factor for its development(1,2 ). However, KS can occur in the absence of HIV infection(3-5) and the risk of KS development varies widely even among HIV-infected patients, with homosexual men with AIDS being 20 times more likely to develop K S than AIDS-afflicted children or hemophiliacs(6). These and other dat a strongly suggest that a sexually transmitted agent or co-factor may be involved in KS pathogenesis(7). Recently, DNA sequences correspondi ng to the genome of a novel member of the herpesvirus family have been identified within AIDS-KS biopsies(8), and several reports indicate t hat these sequences are also present in all forms of HIV-negative KS ( ref. 9-13). These and other findings(14) suggest this new agent, refer red to as KS-associated herpesvirus (KSHV) or human herpesvirus 8 (HHV 8), as a candidate for the putative etiologic cofactor. However, the r ole of this agent in KS remains hotly debated(15). Further progress in understanding its biology has been severely hampered by the lack of a cell culture system for virus growth. Here we report the development of a system for the lytic growth of this virus in a latently infected B cell line and present the first ultrastructural visualization of the virus. This system will facilitate the detailed study of the molecula r biology of viral replication, the testing of antiviral drugs and the development of diagnostic tests for viral infection.