VANCOUVER, BC--The discovery in 1994 of a new human herpesvirus associated with Kaposi's sarcoma (KS) brought some order to the previously contentious discussion about causes of the disease in patients with HIV. Researchers at the 11th International Conference on AIDS further nailed human herpesvirus-8 (HHV-8, also known as Kaposi's sarcoma-associated herpesvirus or KSHV) as the culprit in many, if not most, cases of KS (see also, page 1).
Antibodies against HHV-8 appear in more than three quarters of patients with AIDS prior to the appearance of KS, said Shou-Jiang Gao, PhD. Dr. Gao and colleagues in New York, Pittsburgh, Baltimore, Chicago, Los Angeles, and Atlanta developed a Western blot assay to detect antibodies to two latent nuclear antigens of HHV-8. This assay was then used to look for anti-HHV-8 antibodies in serum samples from 40 patients with AIDS and KS. Samples had been drawn 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 none of 122 general population blood donors.
David Blackbourn, PhD, and associates in San Francisco and Portland showed that the novel herpesvirus-like DNA sequences detected in KS belong to an infectious agent. They found that filtered fluids from HHV-8-infected peripheral blood mononuclear cells (PBMCs) or from PBMCs co-cultured with KS tumor samples could spread the infection to cultured human CD19+ B cells and endothelial cells.
Peter Biberfeld, MD, and colleagues at Karolinska Hospital, Stockholm, found that not only AIDS-associated KS but also endemic KS appears consistently associated with HHV-8 DNA irrespective of stage, tissue, gender, or age. This study included Swedish HIV patients with KS and Tanzanian patients with endemic KS.
Yao-Qi Huang, PhD, and colleagues in New York and Dallas found that 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 with KS and six AIDS patients without KS. HHV-8 DNA sequences were identified with the polymerase chain reaction. HHV-8 was pres-ent in all of the patients with KS, most often in the lung, stomach, prostate, and rectum. HHV-8 was not found in any of 50 samples from non-KS patients.