Zika virus is a dangerous disease which is transmitted by mosquitoes. In some cases, including those in pregnant women, the long-term effects can trigger paralysis, neurodevelopmental defects, or seizures. In a study out of the Sâo Paolo’s Human Genome and Stem Cell Research Center (HUG-CELL) in Brazil, scientists are finding alternate ways to harness this virus that has caused much harm and instead use it for the good.
Scientists at HUG-CELL had already shown that that Zika virus can infect and destroy central nervous system tumors. They were the first to discover that Brazilian Zika can be an effective agent to treat central nervous system tumors. The therapies for these tumors, which usually manifest in children, are rarely effective and have severe side effects, impairing the patients’ quality of life.
Mayana Zatz, a principal investigator for HUG-CELL, is the current author of the study. She says the latest study proves that the approach is safe and effective.
Zatz collected genetic material from discordant twins, only one of whom was infected with a central nervous system tumor. The team then bred cell lines from the material, and infected the cells with Zika to find out how the virus behaved. “That led to the idea of testing the virus on brain tumors, which are rich in this type of cells,” Zatz explains in a media release.
Researchers worked with BALB/c nude mice, a type of laboratory animal that is hairless, lacks a normal thymus gland, and has a defective immune system because of a genetic mutation. Nude mice are deficient in T lymphocytes and are often used in cancer research because they do not reject tumor cells.
The first step was to analyze the safety of the treatment by applying the virus directly to the brains of the tumor-bearing animals. The effect was positive, but tumor growth resumed after 21 days. The researchers then tested serial injections into the brain fluid of mice with the same viral load as the first test. These mice lost a significant amount of weight and died within four weeks. Finally, they injected three doses of the virus into the brains with consistent timing between doses. The results in the mice were positive, allowing the researchers to proceed with the injection of tumor cells into the mice.
Scientists found that the virus did not interact with the cancer cells. There was also no tumor remission within the mice, suggesting that Zika had positive effects on the central nervous system.
Once the scientists found that the treatment was safe and effective, they began to treat the mice with an injection once per week for three weeks. The injections efficiently destroyed the tumor cells without neurological damage or injury to other organs, thus rendering an increase in survival time.
A new study has now begun involving the recruitment of dogs with brain tumors. “Dogs are extremely important models before we start thinking of tests involving patients,” says Zatz. “They have tumors that closely resemble human tumors and a preserved immune system. It will be possible to analyze different types of tumors.”
The research is published in the journal Viruses.
Article by Rhonda Errabelli
