Simian virus 40 (SV40)-like DNA sequences not detectable in finnish mesothelioma patients not exposed to SV40-contaminated polio vaccines.

Occupational asbestos exposure can be demonstrated in 80% of mesothelioma cases. A possible role of simian virus 40 (SV40) in the etiology of mesothelioma was raised because several studies reported the presence and expression of SV40-like DNA sequences in human mesotheliomas. It is also known that expression of SV40 large T antigen inhibits cellular Rb and p53. This suggests that SV40 might render infected cells more susceptible to asbestos carcinogenicity. The SV40-like sequences are suggested to have arisen from contaminated polio vaccines. Millions of people in the United States and most European countries were inoculated with SV40-contaminated polio vaccine in 1955-1963. However, in Finland, where polio vaccination started in 1957, no SV40-contaminated vaccine was used. We used a polymerase chain reaction-based method to test for the presence of SV40-like sequences in DNA extracted from the frozen tumor tissues of 49 Finnish mesothelioma patients, most of whom had been occupationally exposed to asbestos. All of the Finnish tumor tissues tested negative for SV40-like sequences. The results suggest that the SV40-like sequences detected in mesothelioma tissue in some previous studies may indeed originate from SV40-contaminated polio vaccines. It is a matter of speculation whether the absence of SV40 infection has contributed to the relatively low incidence of mesothelioma in Finland (1/10(5) in 1990-1995).