Brazil scientists discover Zika virus inhibitor

Scientists from the Oswaldo Cruz Foundation (FIOCRUZ) in Pernambuco discovered a substance that can block Zika virus. However, years of study are still necessary before the 6-methylmercaptopurine riboside (6MMPr) can be turned into a medicine and be produced in large scale.

The substance is believed to imitate part of the virus, which is inserted into its genome for replication. The success obtained by the specialists reached over 99%.

The study was published in the International Journal of Antimicrobial Agents last Friday (Aug 11), but the institution only announced the discovery this week.

The synthetic substance belongs to the Thiopurine group, along with medicines used to treat cancer. This particular type, however, was never used; FIOCRUZ researchers worked with 6MMPr in another study, to fight the virus that causes canine distemper, a dog disease. “We have identified its activity against canine distemper. And since it's an RNA virus, just like Zika virus, we've come up with the hypothesis that it would also work against Zika,” said research coordinator Lindomar Pena.

The tests were conducted on epithelial and neural cells of both monkeys and humans. For every thousand viruses, 996 were eliminated with the 6MMPr, which amounts to over 99%. Also found was that the higher the dose the higher its efficiency, and that the earlier the substance starts to work, the bigger its success.

In order to fight Zika virus, the substance imitates part of the virus structure in order to “trick” it. According to the research coordinator, when the virus replicates its genome, it needs tiny structural blocks. For the sake of illustration, he compared the process with a brick wall. It is as if the 6MMPr was able to imitate one of the bricks, so that when Zika virus “builds” the wall, it would stop replicating.

Furthermore, the substance proved safe for use in neural cells. “It's going to have few side effects on the nervous system, because if it were more toxic it would be a negative sign. It shows just the opposite, with few toxic agents compared to epithelial cells. In epithelial cells, it's less serious,” Pena said.

Long way to go

Despite the achievement, there are still several stages—and years—ahead of  the scientists before the substance is produced in large scale as a medicine. According to Lindomar Pena, this takes an average of ten years. “But, because of the importance and the gravity of Zika, this could be reduced to half,” he argued.

The next step is a test on mice. Other two species are necessary before human subjects are used. In order to ascertain whether it is possible to use a potential medicine on pregnant women to protect the baby, further testing on pregnant female animals is necessary. “If it's harmful, we can improve the substance by making chemical changes. We already have a partnership with the Federal Rural University of Pernambuco for that,” he concluded.

Translated by Fabrício Ferreira