Contributed by Guest Blogger: J. Warren ’14
Cancer is the second leading cause of death in the world today. This fact has made cancer research one of the leading studies in medicine, and any advancement in the field of cancer treatment is quite impactful. One of the more modern (and promising) approaches to treating cancer is through the use of viruses. An oncylitic virus is one that has been modified to infect cancer tissue in the body while not causing disease to the host. This should be possible due to the heightened susceptibility to viral infection of tumor cells, which have defects in certain antiviral response. The appeal of oncylitic viral infection is its ability to spread through the host, allowing it to attack any and all cancerous cells.
One highly attractive oncylitic virus is a mutant of vesicular stomatitis virus (VSV). A recent study investigated the effects of a mutant strain of VSV (rM51R-M) on breast cancer in both rats and humans. Though the virus was able to infect and kill the breast cancer cells without causing disease in the host mice, and could effectively destroy the tumors in vitro, unfortunately the research found that in vivo the viral infection is not sufficient for curing a host of breast cancer, and that VSV does not infect tumorigenic cells any more than normal cells.
Researchers grew several strains of human mammory epithelial cells with varying oncogenicity (chance to turn cancerous) and exposed them to varying multitudes of infection by rM51R-M. They observed that there was no significant difference in viral proliferation between the strains. They also looked at the effects of rM51R-M in mice with breast cancer, tracking the growth rate of the tumors according to the amount of infection.
Though the findings don’t amount to an effective way of defeating breast cancer, it does add valuable knowledge to the field. Future experiments can easily expand on these methods: using this data as a control, researchers could test other types of cancer, other oncylitic viruses, or perhaps the effects of compounding additional treatments. Perhaps this will also drive scientists to create completely new, engineered viruses that are able to infect only the tumor cells present and, some day, be able to completely eliminate multiple types of cancer.
Is this virus useful for attacking breast cancer cells? I wonder if certain viruses can only attack certain cancer cells. That would be an interesting experiment to conduct. Rachel is right in saying this is a very scary prospect, especially when scientists are able to create new viruses. This could easily get out of hand, and the public might not be too fond of the idea.
Sam makes an interesting point in saying that the virus will likely mutate and come to infect healthy cells. This would undoubtedly be bad for the host organism, but then again, current treatment options for breast cancer- surgery, radiation, and chemotherapy- are not too kind to patients either. It’s clear that this type of treatment is by no means ready to be introduced to the general public but it does seem that with some additional modifications, this strain of virus is promising for future advancements.
I think the prospect of using Viruses for our benefit is interesting yet quite scary. It is interesting in that it is a possible way to distinguish cancerous cells from healthy ones and only harm the right ones. It is scary because it is a virus and at the end of the day all it really wants is to maximize proliferation. The virus accomplishes this by its responses to the forces of natural selection. If a mutant of the virus is able to infect and replicate in not only the cancerous cells but healthy host cells, then that virion is going to be more “fit” and will eventually become dominant. This would be disastrous for the cancer patient. It seems like for this to be an effective and reliable treatment the virus would have to have some kind of fundamental component that would only allow infection of cancerous cells.