Human papillomavirus (HPV) vaccine is an experimental vaccine that targets certain sexually transmitted strains of human papillomavirus that are associated with the development of cervical cancer and genital warts. The only two HPV vaccines currently on the market are Gardasil and Cervarix.
Introduction:
Of the more than 200 known HPV types, 37 are known to be transmitted through sexual contact. Infection with sexually transmitted HPVs is very common in adult populations worldwide. Although a few HPVs, such as types 6 and 11, can cause genital warts, most genital HPV infections come and go without ever causing any symptoms. However, lingering infections with a subset of about 19 "high-risk" HPV types can lead to the development of cervical cancer or other genital/anal cancers, and some forms of HPV, particularly type 16, have been found to be associated with a form of throat cancer. Only a small percentage of women with HPV go on to develop cervical cancer.
The latest generation of preventive HPV vaccines are based on hollow virus-like particles (VLPs) assembled from recombinant HPV coat proteins. The vaccines target the two most common high-risk HPVs, types 16 and 18. Together, these two HPV types cause about 70 percent of all cervical cancer. Gardasil also targets HPV types 6 and 11, which together cause about 90 percent of all cases of genital warts.
Gardasil and Cervarix are designed to elicit virus-neutralizing antibody responses that prevent initial infection with the HPV types represented in the vaccine. The vaccines have been shown to offer 100 percent protection against the development of cervical pre-cancers and genital warts caused by the HPV types in the vaccine, with few or no side effects. The protective effects of the vaccine are expected to last a minimum of 4.5 years after the initial vaccination.
While the study period was not long enough for cervical cancer to develop, the prevention of these cervical precancerous lesions (or dysplasias) is believed highly likely to result in the prevention of those cancers.
Although a 2006 study suggests that the vaccines may offer limited protection against a few HPV types that are closely related to HPVs 16 and 18, it is clear that other high-risk HPV types can circumvent the vaccines.[4] Ongoing laboratory research is focused on the development of HPV vaccines that will offer protection against a broader range of HPV types. There is also substantial research interest in the development of therapeutic vaccines, which seek to elicit immune responses against established HPV infections and HPV-induced cancers.
History of HPV vaccines:
The vaccine was developed in parallel by researchers at Georgetown University Medical Center, the University of Rochester, Queensland University in Australia, and the U.S. National Cancer Institute. Intellectual property resulting from the discovery has been contentious. Following over 10 years of adjudication, the European Patent Office awarded the controlling patent for the cervical cancer vaccine to the University of Rochester. Following this, the U.S. Patent Office recognized Georgetown University as having the dominant patent claim in the United States, based on filing date.
In 2006, the U.S. Food and Drug Administration approved the first preventive HPV vaccine, marketed by Merck & Co. under the tradename Gardasil. Early in 2007, GlaxoSmithKline filed for approval in the United States for a similar preventive HPV vaccine, known as Cervarix. In the European Union, GlaxoSmithKline filed the application for approval in March 2006.