Cervical CA vaccine, approved yesterday, was a product of a rather amazing scientific journey, a process that took scientists and doctors to cows and nuns:
The research project in Rochester began with an effort to develop a blood test to detect infection by a class of viruses known as human papillomaviruses or HPV, which cause warts as well as cervical cancer. To do so, the researchers needed large amounts of papillomavirus – and while there are plenty of warts in this world, finding people willing to collect and analyze them is quite a different story. So as a starting point the team turned to bovine papillomavirus or BPV in cows, and Bonnez found himself visiting veterinarians and others with access to cows with warts, seeking samples.
In the world of warts, cows offer a particularly plentiful lode of papillomavirus, Bonnez said, because they are particularly rich in viral particles. Many other warts, such as genital warts in humans, don’t provide enough viral particles.
The trips to the countryside were successful – Bonnez ultimately collected enough cow warts and still keeps a stash in his laboratory freezer – and the research moved ahead. The next step involved assessing the test, and doctors needed a large control group of adults who were unlikely to have been infected with genital HPV. So the group turned to area nuns and priests who allowed themselves to be polled about their sex lives and who donated blood samples. (Clergy have been crucial to other Rochester research projects as well; several have volunteered to test HIV vaccines, for instance.)
A few years into the project, the scientists faced difficulty improving their blood test using BPV, so they scrapped the cow warts and learned to grow human HPV in the laboratory. Soon after that they discovered that the three-dimensional outer shell of the virus was crucial to creating an immune response that could prevent infection.
The scientists then turned their attention to determining how to make a safe, non-infectious form of the viral coating, and that led them to figure out how to make harmless virus-like particles (VLPs) to trigger the same immune response. They did this by putting an HPV gene into insect cells using a virus called baculovirus, which infects insects; the HPV gene then produces VLPs that mimic the shape of real HPV particles. The team made VLPs of the specific cancer-causing strains of HPV and showed that they protected against the disease. VLPs are crucial to the vaccine approved today by the FDA, as well as another cervical cancer vaccine in development; both protect against multiple strains of the virus.
The new vaccine is given as a series of three shots administered a few months apart. Most doctors say the vaccine needs to be given before a person becomes sexually active to do the most good.
More from the press office at the University of Rochester Medical Center…
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