KAPOSIS SARCOMA-ASSOCIATED HERPESVIRUS GENE-EXPRESSION IN ENDOTHELIAL(SPINDLE) TUMOR-CELLS

The recent discovery of DNA sequences of a new human herpesvirus in Ka posi's sarcoma (KS) has fueled speculation that this virus might cause KS. The mere presence, however, of a virus in a complex multicellular tumor like KS could just as well be construed as evidence of a passen ger agent. We sought stronger evidence linking the KS-associated herpe svirus (KSHV) to tumor formation by using in situ hybridization to inv estigate the specificity, constancy, and timing of KSHV gene expressio n in KS tumor cells. Here me document expression of a 700-nucleotide v iral RNA in every KS tumor examined, from the earliest histologically recognizable stage to advanced tumors in which the vast majority of id entifiable spindle tumor cells contain this transcript. Two other KSHV RNAs were also detected in a smaller fraction of the tumor cells in a ll but the earliest lesion. These viral RNAs,vere expressed to relativ ely low levels in this subset; because one of these RNAs encodes a maj or viral capsid protein, these cells mag be producing KSHV. We did not find these KSHV genes expressed in a variety of other tumors and prol iferative processes, but we did detect viral gene expression in prosta tic tissue, supporting a possible mechanism for sexual transmission of KSHV. The close relationship between KS and KSHV gene expression is c onsistent with the hypothesis that KSHV is directly involved in the et iology and pathogenesis of KS.