Our data indicate a strong association between NHL and SV40 and thus a need for innovative therapeutic approaches for this hematologic malignancy.
Xenotropic murine leukemia virus-related virus (XMRV) is a recently discovered human retrovirus that has been found in both chronic fatigue syndrome and prostate cancer patients. Although these findings need further confirmation, there is a potential safety concern regarding XMRV in cell substrates used in vaccines and in transmission by blood transfusion and blood products. We are developing sensitive detection assays for XMRV to evaluate cell substrates and investigate virus transmission by blood transfusion in a monkey model.
Virus-based vaccines are made in living cells (cell substrates). Some manufacturers are investigating the use of new cell lines to make vaccines. The continual growth of cell lines ensures that there is a consistent supply of the same cells that can yield high quantities of the vaccine. In some cases the cell lines that are used might be tumorigenic, that is, they form tumors when injected into rodents. Some of these tumor-forming cell lines may contain cancer-causing viruses that are not actively reproducing. Such viruses are hard to detect using standard methods. These latent, or "quiet," viruses pose a potential threat, since they might become active under vaccine manufacturing conditions. Therefore, to ensure the safety of vaccines, our laboratory is investigating ways to activate latent viruses in cell lines and to detect the activated viruses, as well as other unknown viruses, using new technologies. We will then adapt our findings to detect viruses in the same types of cell substrates that are used to produce vaccines. We are also trying to identify specific biological processes that reflect virus activity.
Although the results showed that PCV infection may not have occurred under previous culture conditions, the recent cases of vaccine contamination emphasizes the need for continued efforts to reduce the likelihood of introducing viruses from animal-derived materials used in product manufacture
But the increasing number of target species for vaccines, the diversity or the origin of biological materials and the extremely high number of known and unknown viruses and their constant evolution represent a challenge to vaccine producers and regulatory authorities
These data suggest that there may be an increased incidence of certain cancers among the 98 million persons exposed to contaminated polio vaccine in the U.S.; further investigations are clearly justified.