Serum HHV8 DNA and Tat antibodies in Kaposi's sarcoma patients with and without HIV-1 infection.

Human herpesvirus 8 or Kaposi's sarcoma-associated herpesvirus (HHV8/KSHV) is believed to be the most important etiopathological factor of Kaposi's sarcoma (KS) and some specific types of malignant lymphomas. The diagnostic and prognostic significance of serum viral load in endemic (African) areas is poorly understood. In AIDS-related KS (AKS) it has been shown that HIV-Tat may be of pathogenic importance and that immunoreactivity to Tat may have prognostic significance. Here we report on the quantitative analysis of HHV8 DNA in serum from Tanzanian patients with KS (n = 19), either AIDS-related (AKS) (n = 14) or endemic KS (EKS) (n = 5) and non-KS control individuals (n = 4). Fourteen AKS sera were also tested for HIV-tat antibodies by a direct ELISA assay. In AKS patients detectable (12 out of 14) serum HHV8 DNA levels showed a median of 1400 copies/ml as compared to a median of 200 copies/ml for EKS, but for one AKS case with an exceptionally high level (25,500 copies/ml). The serum HHV8 DNA levels were usually higher in males (n = 17; median 580 DNA copies/ml) as compared to females (n = 6; median 120 DNA copies/ml) and in early, patch stages (n = 8; median 2,750 copies/ml) as compared to late, nodular stages (n = 11; median 200 DNA copies/ml). Of fourteen sera from AKS patients, seven were positive for antibody against HIV-1 tat. Epitope analysis of the anti-tat antibody spectrum showed reactivity to various non-functional sites, but not towards the functional epitopes 46-60 (TAR-binding region).

Cross-talk between human herpesvirus 8 and the transactivator protein in the pathogenesis of Kaposi's sarcoma in HIV-infected patients.

AIDS-associated Kaposi's sarcoma (AKS) is particularly aggressive and it is one of the principal neoplasms in regions of Africa affected by both high endemic HHV8 and epidemic HIV infection. In this study, serum samples from 18 patients with Kaposi's sarcoma from Tanzania, mostly males (n = 15 vs 3), were subjected to analysis with respect to HHV8-DNA load and antibody spectrum against the HIV-1 tat protein. Of the 18 patients, 14 were HIV-1-positive. The median HHV8 virus load in the HIV-1-positive group was 2075 DNA copies/ml, compared to 450 copies/ml in the HIV-1-negative group. In the HIV-1-positive group, the males had a higher HHV8-DNA virus load as compared to females (median: 4600 vs 1400 genome copies per ml). Since tat can promote AKS development (4-6) by intercellular signalling pathways, and these signals can be abolished by anti-tat IgG (7-9), we have examined the anti-tat IgG spectrum in this study. It would be expected that the levels of serum HHV8-DNA are higher in KS patients who have low anti-tat IgG titer, or who are anti-tat IgG-negative. In the present study, seven out of fifteen AKS patients were positive for anti-tat IgG. Although, we have not seen a strict quantitative relationship between serum anti-tat IgG and HHV8-DNA levels, our data appear to suggest a correlation between the two parameters. In view of these observations and the published data, we suggest that cross-signalling pathways between the tat protein and HHV8-DNA are involved in the complexity of pathogenesis of Kaposi's sarcoma.

Docking studies reveal a selective binding of D-penicillamine to the transactivator protein of human immunodeficiency virus type 1.

DOCK and Affinity studies were carried out to study the binding of D- and L-penicillamine to the transactivator protein (tat) of human immunodeficiency virus type 1 (HIV-1). These studies reveal a selective binding of D-penicillamine to the cysteine-rich region covering amino acid residues 20-38 of the tat protein. A careful analysis of the components of the binding energy of the D- and L-isomers reveals that the D-isomer has a more favorable van der Waals interaction resulting from an optimal placement of the dimethylthiomethyl side chain in the binding site. This observation matches the experimental data that D-penicillamine is a more potent inhibitor of tat-mediated transactivation than the L-isomer. The docking and experimental data offer an interesting approach to design structural molecules with potential application to block signal functions of the tat protein in HIV-1 pathogenesis.

Evaluation of carcinogenic potential of two nitro-musk derivatives, musk xylene and musk tibetene in a host-mediated in vivo/in vitro assay system.

We have developed a host-mediated assay system for detection of the transforming activity of chemical carcinogens on peritoneal macrophages. Directly, as well as indirectly acting carcinogenic substances, administered intraperitoneally to NMRI mice, could be examined in this way. Resident macrophages were recovered by peritoneal lavage from treated and untreated mice and cultured in soft agar. After 5-6 days the normal and transformed cells could be distinguished. Statistical analysis comparing cells from musk xylene- or musk tibetene-treated animals with those from control mice proved that the test is positive. Musk xylene and musk tibetene revealed a cell-transforming potential that showed a dose-dependent response in our host-mediated assay system. We have succeeded in establishing permanent cell lines from mice treated with musk xylene, or musk tibetene. The oncogenicity of these cell lines was tested in athymic nu/nu mice. Animals injected subcutaneously with these cells (1 x 10(6) cells at each side of the neck) developed tumors at the injection sites within 3 weeks of treatment. The experimental data reported here lead to the conclusion that musk xylene, as well as musk tibetene, have carcinogenic activity. In contrast to the negative results for mutagenicity and genotoxicity, a non-genotoxic mechanism for the carcinogenicity of musk xylene and musk tibetene must be considered.