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Cervical cancer: new vaccination concept against carcinogenic human papilloma viruses
Cervical cancer is the third most common cancer in women. However, the risk of developing this can be significantly reduced: with HPV vaccination. Researchers have now developed a new vaccine against carcinogenic human papilloma viruses.
Third most common cancer in women
Cervical cancer caused by certain human papilloma viruses (high-risk HPV) is the third most common cancer in women worldwide. Experts estimate that in Germany more than 4,000 women develop this cancer each year - around 1,500 die from it. Well over 80 percent of cases are diagnosed in developing countries, especially in Africa and South America. However, the risk of developing this type of cancer can be significantly reduced: with the HPV vaccination. At the German Cancer Research Center (DKFZ), scientists have now developed a completely new vaccination concept. The vaccine is inexpensive and protects against almost all carcinogenic HPV types.
Risk HPV is transmitted during sexual intercourse, infections are very common. It is believed that up to 80 percent of the female population is exposed to these viruses in their lifetime.
In addition to cervical cancer, infections with high-risk HPV are also associated with mouth and throat tumors.
Vaccination can provide protection.
Reduce the number of cervical cancer cases
In Germany, the Standing Vaccination Commission (STIKO) has recommended HPV vaccination for girls from 9 years of age for years. This is said to significantly reduce the number of cervical cancer cases.
"Various vaccines are currently available in Germany that protect against infection with the most common carcinogenic HPV types," said Bavaria's Minister of Health Melanie Huml in a recent statement.
“My goal is that more girls than ever choose to be vaccinated - preferably before the first big love. Because girls can become infected with HPV the "first time", "explained the Minister.
However, gynecologists still recommend HPV vaccination even after the first sex. Even if you have already had an infection with HPV.
Temperature sensitive and expensive
The previously available vaccines against cancer-causing HPV are effective, but there are limitations, according to a statement by the Wilhelm Sander Foundation, published by the "Informationsdienst Wissenschaft" (idw).
They are temperature sensitive and therefore require refrigerated transport throughout, which is a logistical problem in some countries. Their production is also complex and expensive. They also only work against some of the carcinogenic HPV types.
"Our major goal is to increase vaccination rates against HPV worldwide, especially in countries that have limited resources," said Martin Müller from the DKFZ.
"Our new, heat-stable vaccine, which is cheap to produce and protects against almost all cancer-causing HPV types, is a first major step in this direction."
Stimulation of the immune system
Vaccines that protect against HPV infections stimulate the immune system to produce protective antibodies. The vaccines already available are based on so-called virus-like particles.
This is how researchers describe empty protein shells of the virus that contain no genetic material. They are produced in yeast or insect cells.
Vaccinated people then develop antibodies that prevent viruses from infecting the cells. Like flu vaccines and almost all other prophylactic vaccines, HPV vaccines only protect when given before infection.
The HPV vaccine newly developed in Martin Müller's work group is not based on virus-like particles, but on small protein snippets of the virus envelope (HPV envelope proteins).
With this vaccination, too, the aim is to trigger the formation of protective antibodies. To ensure that this happens efficiently, Müller and colleagues have placed the small fragments of the HPV coat proteins, the so-called L2 epitopes (molecular sections of the viral antigens), of the eight HPV types 16, 18, 31 33, 35, 6, 51 and 59 in the thermostable Scaffold protein (thioredoxin) of a heat-loving bacterium inserted.
The bacterial thioredoxin (Trx) thus carries all the epitopes of the eight HPV antigens (cross neutralization epitopes). The immune system can now produce specific antibodies against each of these epitopes, which bind to the surface of the virus and thus protect the body against HPV infections.
Protection against almost all cancer-causing HPV
In addition, the working group has made further progress by means of a new process:
By adding the so-called OVX313 domain (protein domain: smallest, stably folded structure of amino acids within a protein with the function of binding other molecules), seven Txr-L2 proteins are combined to form macromolecules (heptamers) of the vaccine protein. This significantly increases the effectiveness of the vaccine.
The vaccine protein is produced in Escherichia coli (intestinal bacteria). While the thioredoxin comes from a thermophilic bacterium (Pyrococcus furiosus) and is very heat-stable, Escherichia coli has its optimum temperature at 37 ° C and is therefore not heat-resistant.
"That is why we can very easily purify the vaccine protein at high temperatures, all other bacterial proteins are destroyed," Müller explained the advantages of the process.
In addition to this extraordinary stability, the vaccine has another advantage: it protects against almost all carcinogenic HPV and a number of so-called "low risk" HPV.
Improve HPV vaccination rates in poorer countries
With the help of the project from the Wilhelm Sander Foundation, the vaccine was improved and characterized in detail.
The preclinical results suggest that the vaccine can protect against almost 99 percent of all HPV-related cases of cervical cancer.
Protection against other types of HPV that cause skin diseases and cancer of the throat and anal area is also conceivable.
With its many beneficial properties, especially in poorer countries, the new vaccine is intended to help significantly improve the still inadequate HPV vaccination rates today. (ad)