In 1960, researchers discovered Simian virus 40 (SV40). Shortly afterward it was discovered that SV40 was also present in the injectable polio vaccine (it was not present in the oral version of the vaccine). Kidney cells from rhesus monkeys were used to prepare the vaccine, and it turned out that those cells were infected with SV40. In the early 1960s, researchers ensured that the polio vaccine was produced using cells that were not infected with SV40.
People were potentially exposed to SV40 for more than a decade, however, and over the years there have been any number of hypotheses that one illness or another has been caused by SV40 exposure from the polio vaccine. The latest claim is that SV40 increased the risk of non-Hodgkin lymphoma, a blood cancer. This claim was given some impetus by the discovery of SV40 in NHL tumors.
A population-based study of almost 1,400 individuals, however, suggests that there is no increased risk of non-Hodgkin lymphoma associated with exposure to SV40. Researchers at the National Cancer Institute tested blood samples from 724 patients with non-Hodgkins lymphoma and from 622 matched control patients without non-Hodgkins lymphoma.
The samples were tested at two independent laboratories. The first laboratory reported SV40 in 7.2 percent of the NHL patients and 10.5 percent of the control group. The second laboratory reported SV40 in 9.8 percent of NHL patients and in 9.6 percent of the control group. The results indicate there is likely no increased risk of developing NHL among individuals exposed to SV40.
Researchers also looked at incidence levels of specific types of non-Hodgkin lymphoma and also found no increased risk associated with SV40 exposure as well.
Monkey virus exposure did not raise lymphoma risk. Reuters Health, September 14, 2004.
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