Hope in the Fight Against Zika
Ever since the Zika outbreak began in Brazil last year, scientists have suspected that the bacteria called Wolbachia might protect mosquitoes from the Zika virus. Now, researchers have confirmed this hunch, providing the first solid evidence that releasing Wolbachia-infected mosquitoes into the wild could help stop the Zika epidemic.
“We are pretty sure that mosquitoes carrying Wolbachia will have a great impact on slowing Zika transmission in the field,” said Luciano A. Moreira, a biologist at the Oswaldo Cruz Foundation in Belo Horizonte.
In 2009, Scott L. O’Neill, a professor at Monash University in Australia, and his colleagues reported that a type of Wolbachia normally found in flies could also infect mosquitoes, and that once in residence, the bacterium blocked dengue viruses from attacking its new hosts.
“It was just curiosity-based work, total serendipity,” Dr. O’Neill said. An estimated 390 million people worldwide are infected with dengue each year, and there is no vaccine or cure. However, if mosquitoes carrying the infection are protected from it, they cannot transmit the virus to humans. So through a program called Eliminate Dengue, Dr. O’Neill has led a series of experiments to test Wolbachia in the field.
In 2011, the program’s team released hundreds of thousands of Wolbachia-carrying mosquitoes in two towns in northern Australia. Five years later, most of the mosquitoes, Aedes aegypti, the species that also transmits the Zika virus, continue to carry Wolbachia.
The scientists have begun similar experiments in other countries, including Vietnam, Indonesia, and Brazil. When the Wolbachia-carrying mosquitoes take over, researchers no longer find locally acquired cases of dengue.
When Zika broke out in Brazil last year, a number of researchers, including Dr. O’Neill, suspected that Wolbachia might work against that virus, too, since Zika and dengue are closely related. In Brazil, Dr. Moreira began an experiment to test the possibility. Jason L. Rasgon, an entomologist at Pennsylvania State University, agreed that the results in Brazil demonstrated that Wolbachia suppressed the Zika virus. It is also possible that Wolbachia could work against other diseases spread by mosquitoes, including yellow fever, which is transmitted by the same species of mosquito.
In other Zika news, a paper-based rapid test for the Zika virus was introduced on Friday, May 6, by a consortium of research groups. The core of the test kit is a piece of paper covered with yellow dots that turn purple in the presence of Zika virus RNA. The test is relatively fast and simple and requires only preliminary heating, which can be done in most laboratories.
The test, which gives results in two to three hours, “is much faster and cheaper than the P.C.R. tests used now,” said James J. Collins, a bioengineer at the Massachusetts Institute of Technology, who is one of the test’s designers. It should cost less than U$1 per test.
The test has worked on Zika-infected monkey blood, which was used because human samples were hard to obtain in time. Now, Dr. Collins said, “we’re talking with groups in Colombia and Brazil about testing it in the field.” The collaboration also included scientists from Harvard’s Wyss Institute, the Broad Institute, Cornell University, Arizona State, and Boston University.
Additionally, two neurology researchers at the Johns Hopkins Hospital in Baltimore, US, have made an important discovery regarding Zika. The laboratory’s initial breakthrough showed that the Zika virus attacked and killed so-called neural progenitor cells, which form early in fetal development and generate neurons in the brain. In April, the team and other collaborators published a study in the journal Cell showing that this assault by Zika resulted in undersize brain organoids – damaged progenitor cells created fewer neurons, leading to less brain volume.
Many other researchers are also rushing to understand how Zika wreaks its damage. Teams in Brazil and at the University of California, San Diego have also found that the virus attacked neural progenitor cells and shrank brain organoids. In Rio de Janeiro, Stevens Rehen, a neuroscientist at D’Or Institute for Research and Education, said the Brazilian team was also testing drugs, seeking one that blocked the Zika virus. However, they can test only those drugs approved in Brazil; importing drugs from elsewhere involves weeks of bureaucracy. “The idea is to be fast,” Dr. Rehen said.
There is still much more to learn about Zika and how it affects fetal cells. One specialized lab at the National Center for Advancing Translational Sciences is testing drugs on neural progenitor cells, hoping to find compounds that can stop the virus. Rapidly testing thousands of compounds in varying doses, the lab has already zeroed in on a promising candidate. If the drug succeeds in further testing, it could allow scientists to skip much of the evaluation necessary for creating new drugs or vaccines.
In another Zika development, women in Brazil are to be offered free subscriptions to a computer app for their smartphones in the hopes of controlling the Zika virus epidemic. The one million free subscriptions to the computer app, invented in Sweden and worth over U$25 million, will be offered to Brazilian women as a means of temporarily postponing pregnancy until the virus is brought under control.
The app, called Natural Cycles, works by identifying a woman’s ovulation cycle and fertility window by tracking her period and temperature, then notifying the woman on the days when she is and is not fertile. A recent study found the app’s prediction system to be wrong only 0.05 percent of the time.
This is in line with the advice given by health organizations around the world for women to consider postponing pregnancy in areas where Zika is spreading. Brazil has been hardest hit by Zika, a mosquito-borne virus that the World Health Organization (WHO) deemed a public health emergency in February.
As of April 27, 2016 there were over 30 pregnant women in the US currently infected with Zika, with the latest case confirmed in Connecticut. In total, the US has reported over 400 Zika infections, all travel related.
Scientists across the world have been scrambling to find some sort of immunization against the virus, which is extremely difficult to combat as the mosquitoes bite both during the day and at night and can live indoors and outdoors. As the summer rapidly approaches in the northern hemisphere, concerns for a US outbreak are mounting, with Zika claiming its first victim last month in Puerto Rico – a 70-year-old man who died from complications from the virus.
The Zika virus has been reported in 55 countries worldwide, 42 of which had never had any outbreaks previous to 2015. Zika is especially dangerous for pregnant women, as it is linked to several severe birth defects transferred to the fetus, including microcephaly. Zika has also been linked to Guillain-Barré syndrome, where a person’s immune system attacks the nerves connecting the brain and spinal cord, which can lead to temporary paralysis. Unlike microcephaly, most people recover from Guillain-Barré.
Brazil, which only allows abortion in cases of rape, or when the mother’s life is in danger or the baby will not survive, has over 1,000 confirmed cases of microcephaly.
[Research for this article comes from The New York Times and CNBC.com]