Scientists from Brazil tested virus zika for the treatment of malignant tumors of the nervous system on three dogs. The therapy caused no side effects, has led to the improvement of the General condition and life expectancy of dogs. The virus didn’t infect healthy brain cells, but launched the body’s immune response, resulting in the size of tumors decreased. The article is tentatively accepted in the journal Molecular Therapy.
Tumors of the Central nervous system often malignant and lead to death. There are a number of aggressive types of treatment, but they are ineffective and carry many side effects for surviving patients. The fact that the blood-brain barrier — a boundary that will not allow to the brain of foreign matter — prevents the immune system to turn on full power.
Since then, as the year 2015 has approved the first virotherapy for the treatment of melanoma, researchers are trying to find viruses that would help in the fight against other types of cancer. The zika virus was successfully used for the destruction of tumors of the Central nervous system in the lines of human cells and mouse brain. However, before to introduce the virus into clinical practice, it is necessary to test its efficacy and safety on model organisms that are closer to the person. In addition, it is important to test the drug on individuals who have the disease occurs spontaneously, and an immune response develops in a natural way — in mice cancer cause artificially. As of animals for testing new cancer therapies are often used dogs. Malignant tumors develop them spontaneously, and the clinical and histological manifestations of cancer are close to those in humans.
Caroline Kaid (Kaid Carolini) from the University of são Paulo, and her colleagues investigated the effect of injections of Brazilian virus Zeke’s three dogs, who with the help of magnetic resonance imaging, was diagnosed with a massive brain tumor at a late stage. The virus was introduced interdecile (under the sheath of the spinal cord), first a small dose, and after some time of observations, the second 10 times more. To prevent transmission of the virus, dogs were not allowed out of the clinic before were convinced that their biological fluids left viral particles.
As a result of therapy dogs do not experience any side effects and symptoms of virus infection. Neurologic manifestations of cancer has gone down, and the two animals lived another 80 and 150 days after first injection (average dog die via 24-33 days after they have diagnosed tumor). The third animal was also initially got better, but after 18 days, his condition deteriorated, mainly due to cardiomyopathy evolved in parallel. In all three cases, the owners decided to euthanize the dogs.
The size of the tumors at first increased, but this is a known effect of protective reactions of organism, which is due to the influx of immune cells in the lesion focus. Then, within months after start of therapy, the diameter of the tumors was significantly decreased. The dog that lived the longest, after 4 months of treatment, the tumor again began to increase.