The Key to Cancer
The so-called virotherapy appeared as an offshoot of cancer immunotherapy. The essence of the technique is that the virus specifically recognizes cancer cells and destroys them without touching healthy ones. This idea was suggested to scientists by nature – such viruses exist by themselves, and the main task of researchers is to tune them to specific types of cancer. In the USA, one type of virotherapy aimed at stage IV melanoma has been approved by the FDA (FDA). Many virotherapy techniques are currently under development, as well as at various stages of clinical research.
The Seneca Valley Virus (Seneca Valley Virus) is the object of particularly close attention of the developers of cancer virotherapy. The fact is that it is able to recognize about 60 percent of all types of human cancers.
As it turned out, this is due to the anthrax toxin receptors: on the surface of healthy cells there are receptors of the second type (Anthrax toxin receptor 2, ANTXR2), while on cancer cells there are receptors of the first (ANTXR1). The virus specifically binds to the receptors of the first type, ignoring the rest.
Scientists from the Okinawa Institute of Science and Technology and the University of Otago wondered why the Seneca virus recognizes one type of receptor and does not recognize another, practically no different from the first?
In the course of the work, the researchers saw that the virus specifically binds to exactly the part of ANTXR1 that distinguishes it from ANTXR2, according to the "key-lock" principle.
The capsid proteins of the Seneca Valley virus are shown in blue, green and red, and the ANTXR1 receptor is purple.
Understanding this mechanism is important in order to avoid an immune response. When a virus enters the human body as part of a vaccination or by itself, the task of paramount importance is to get rid of the virus, to destroy it. Seneca Valley virus has already demonstrated its ability to fight cancer in phase I clinical trials in pediatric solid tumors and phase II studies in small cell lung cancer. But there is one problem: the body develops immunity to the virus within three weeks and eliminates it before its work is completed.
In the case of antitumor therapy, the researchers' goal is to keep the virus in the body and provide it with the opportunity to multiply and do its job of destroying cancer cells. By knowing exactly which fragment of the virus is responsible for binding to the cancer cell, it is possible to change the rest of the virus, thus minimizing the likelihood of an immune response. In addition, it will allow modifying the virus, teaching it to recognize other receptors, thereby adapting it to different types of tumors.
Article by Jayawardena el al. The structural basis for Anthrax Toxin Receptor 1 recognition by Seneca Valley Virus is published in PNAS Journal.
Anastasia Poznyak, portal "Eternal Youth" http://vechnayamolodost.ru / based on materials from Okinawa Institute of Science and Technologies: Anti-Cancer Virus Fits Tumor Receptor Like a "Key in a Lock" .