Kaposi's Sarcoma and Kaposi's Sarcoma-Associated Herpesvirus (Human Herpesvirus 8): Where Are We Now?

Extract

Kaposi's sarcoma-associated herpesvirus (KSHV) is the eighth and most recently described human herpesvirus (HHV8). During the past 3 years, accumulating evidence leaves little doubt that this virus is the infectious cause of Kaposi's sarcoma (KS). An infectious etiology for KS has been sought for over 3 decades, and a number of viruses and bacteria have been proposed to be the “KS agent.” In each case, the proposed agent has been unable to explain the unusual epidemiology of this tumor.

KSHV, on the other hand, appears to be a nonubiquitous herpesvirus that is present in virtually all KS lesions, regardless of the patient's underlying human immunodeficiency virus 1 (HIV) status. Serologic studies show that the prevalence of KSHV infection in various geographic and risk-group populations parallels the incidence of KS in these populations. For example, the rate of HIV-negative KS follows a pattern where the tumor is least common in the United States and the U.K., more common in Italy and other Mediterranean countries, and most common in Central African countries. The KSHV seroprevalence among blood donors and other control populations follows this same geographic pattern, with less than 5%-10% of U.S. blood donors being KSHV seropositive, whereas the infection rate among persons from Kampala, Uganda, can exceed 50% ( 1 , 2 ) . Similarly, several studies [ see ( 3 , 4 ) ] have found approximately 30% seroprevalence rates, using a variety of antigens, among homosexual men without KS but far lower infection rates among individuals in other HIV risk groups who also have lower rates of developing acquired immunodeficiency syndrome- related KS (AIDS-KS).