Researchers Explore Role of HHV-8 in Kaposi's Sarcoma

VANCOUVER, BC--The discovery in 1994 of a new human herpesvirusassociated with Kaposi's sarcoma (KS) brought some order to thepreviously contentious discussion about causes of the diseasein patients with HIV. Researchers at the 11th International Conferenceon AIDS further nailed human herpesvirus-8 (HHV-8, also knownas Kaposi's sarcoma-associated herpesvirus or KSHV) as the culpritin many, if not most, cases of KS (see also, page 1).

Antibodies against HHV-8 appear in more than three quarters ofpatients with AIDS prior to the appearance of KS, said Shou-JiangGao, PhD. Dr. Gao and colleagues in New York, Pittsburgh, Baltimore,Chicago, Los Angeles, and Atlanta developed a Western blot assayto detect antibodies to two latent nuclear antigens of HHV-8.This assay was then used to look for anti-HHV-8 antibodies inserum samples from 40 patients with AIDS and KS. Samples had beendrawn an average of 47 months before KS onset.

Antibodies were found in sera of 31 of 40 patients with KS (77.5%)versus 7 of 40 AIDS patients who did not have KS (17.5%) and noneof 122 general population blood donors.

David Blackbourn, PhD, and associates in San Francisco and Portlandshowed that the novel herpesvirus-like DNA sequences detectedin KS belong to an infectious agent. They found that filteredfluids from HHV-8-infected peripheral blood mononuclear cells(PBMCs) or from PBMCs co-cultured with KS tumor samples couldspread the infection to cultured human CD19+ B cells and endothelialcells.

Peter Biberfeld, MD, and colleagues at Karolinska Hospital, Stockholm,found that not only AIDS-associated KS but also endemic KS appearsconsistently associated with HHV-8 DNA irrespective of stage,tissue, gender, or age. This study included Swedish HIV patientswith KS and Tanzanian patients with endemic KS.

Yao-Qi Huang, PhD, and colleagues in New York and Dallas foundthat HHV-8 can be detected in the organs where KS most often occurs,including the lymph nodes, lung, stomach, spleen, prostate, esophagus,and rectum.

Dr. Huang studied autopsy specimens from five AIDS patients withKS and six AIDS patients without KS. HHV-8 DNA sequences wereidentified with the polymerase chain reaction. HHV-8 was pres-entin all of the patients with KS, most often in the lung, stomach,prostate, and rectum. HHV-8 was not found in any of 50 samplesfrom non-KS patients.