Texas A&M Entomology Research Network

zika

AgriLife Research team makes strides in fight against Zika

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by Steve Byrns, Texas A&M AgriLife Communications

Dr. Kevin Myles, Texas A&M AgriLife Research scientist at Texas A&M University, discusses research notes with AgriLife Research associate scientist Glady “Hazitha” Samuel. (Texas A&M AgriLife Extension Service photo by Rob Williams)
Dr. Kevin Myles, Texas A&M AgriLife Research scientist at Texas A&M University, discusses research notes with AgriLife Research associate scientist Glady “Hazitha” Samuel. (Texas A&M AgriLife Extension Service photo by Rob Williams)

COLLEGE STATION – There’s a war raging on a tiny battlefield and the outcome could well touch millions of people worldwide threatened by Zika and related viruses. The key ally unlocking the mystery surrounding this conflict is the long-dreaded yellow fever virus.

Dr. Kevin Myles, Glady “Hazitha” Samuel and Dr. Zach Adelman are Texas A&M AgriLife Research scientists at Texas A&M University, College Station, who published “Yellow fever virus capsid protein is a potent suppressor of RNA silencing that binds double-stranded RNA.”

The paper appears in the Proceedings of the National Academy of Sciences. Go to http://bit.ly/2eYsyIQ.

The mystery has been how these viruses get around the insect’s immune response, and the answer is the virus makes a protein that suppresses the immune response, Myles said.

“When mosquitoes are infected with these viruses, there’s a signal that lets the mosquito’s cells know that they are infected, resulting in targeting of the virus by the mosquito’s immune response.

“Something similar occurs in our bodies when we’re infected with these viruses; there are signals our cells detect that let our immune system know all is not well,” he said.

The AgriLife Research team found a protein that is produced by yellow fever virus, as well as Zika virus, West Nile virus and dengue virus, that suppresses the immune response of the mosquito.

“While the mosquito doesn’t want the virus in its body any more than we want it in ours, and is trying to get rid of it, the virus isn’t defenseless,” Myles said. “It’s fighting back and deploying its own countermeasures. Basically this is what’s known as an evolutionary arms race. The survival of this group of viruses depends on their ability to stay one step ahead of the mosquito’s immune response.”

Aedes aegypti mosquito. (Texas A&M AgriLife Research photo by Gabriel Hamer)
Aedes aegypti mosquito. (Texas A&M AgriLife Research photo by Gabriel Hamer)

Now that the scientists know this, there are a couple of options. By using gene drive, a method targeting specific genes, they could go in and tip the scale in the mosquito’s favor. Alternatively, they could give the nod to the virus. In the latter, the virus would actually make the mosquito sick preventing transmission to humans.

“It will also be interesting to see if this protein interferes with the human immune response,” Myles said. “Certainly similar types of proteins have been found in other viruses that are not transmitted by mosquitoes but do infect people, influenza viruses for example.

“If it does interfere with our immune response, it could become a target for vaccine development, not only for Zika virus, but possibly other viruses as well.

“More research is needed before we reach that point though, but as ironic as it may seem, we are using the yellow fever virus, once arguably the most feared pestilence in the Western Hemisphere, to help us defeat the Zika virus and quite possibly others as well.”

Myles and Adelman joined the department of entomology at Texas A&M on Aug.1. The scientists were previously at Virginia Tech and now lead AgriLife Research’s efforts to stop Zika.

Myles is working to understand the basic biology of how viruses such as Zika replicate in mosquitoes, and Adelman’s projects involve creating mosquitoes resistant to viruses such as Zika.

For more information, contact Myles at 979-458-3110, mylesk@tamu.edu .

AIBS to Convene Expert Panel Webinar on Science of Zika, Potential for Genetic Control

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Washington, DC – The Zika virus is the most recent example of a virus spreading rapidly around the world with the assistance of an animal vector – in this case the mosquito Aedes.

On March 15, 2016, the American Institute of Biological Sciences will convene a meeting of scientific experts to discuss the epidemiology of Zika, the potential for genetic control of the mosquito species that transmit it, and the ethical issues associated with the use of this new biotechnology. This webinar program is free and open to the public, but space is limited and pre-registration is required.

The extraordinarily fast spread of the Zika virus has prompted international concern because of its apparent link to birth defects, including microcephaly, in infants born to infected women. The virus may also be linked to cases of Guillain-Barré syndrome, an immune disorder. The World Health Organization has declared the Zika outbreak an international health emergency.

“The control of this disease, among other emerging diseases, is a challenge as people routinely travel around the world, global commerce provides increased opportunities for animal vectors to move into new environments, and climate change allows species to invade new habitats, often exposing the people in the colonized area to new pathogens,” said Dr. Robert Gropp, AIBS Interim Co-Executive Director.

The plants, microbes, and animals with which we share the planet provide us with life sustaining benefits every day. Periodically, however, some of them threaten our well being, such as in the case of Aedes and the Zika virus.

A way to slow the spread of Zika is to control or eliminate Aedes, which is also responsible for the transmission of dengue and chikungunya virus, among other pathogens.

“One line of research to suppress Aedes populations involves a “gene drive,” a genetic construct that once introduced into wild populations is expected to spread rapidly. Such an approach could be designed to bring about a population crash, for example, by distorting the sex ratio in mosquito populations,” said Gropp.

Despite the promise, using gene drives to control wild species raises ethical questions, some of which will be considered in this program. The webinar will also explore aspects of Zika epidemiology and biology.

Speakers are:

  • Davidson H. Hamer, MD, Boston University School of Public Health, Center for Global Health and Development
    Dr. Hamer is a board-certified specialist in infectious diseases, with a particular interest in tropical infectious diseases, and has twenty years of field experience in neonatal and child survival research including studies of micronutrient interventions, maternal and neonatal health, malaria, pneumonia, and diarrheal diseases. He is currently the Principal Investigator for the GeoSentinel Surveillance Network, which performs active surveillance for emerging infections such as Zika using returning travelers, migrants, and refugees as sentinels of disease transmission.
  • Zach N. Adelman, PhD, Virginia Tech, Department of Entomology
    Among Dr. Adelman’s research interests are genetics, gene control, and mosquito-pathogen interactions. Little is known about how mosquitoes defend themselves against foreign DNA elements. What are the effects of transgene insertions on chromosome structure? Will the mosquito recognize and shut down a transgene over time? And what effect will this have on the potential for genetic control? The answers to these questions are of vital importance to the implementation of a successful genetic control strategy.
  • Sahotra Sarkar, PhD, University of Texas, Austin, Department of Philosophy
    Dr. Sarkar specializes in the history and philosophy of science, conservation biology, and disease ecology. He is Professor in the Departments of Integrative Biology and Philosophy at the University of Texas at Austin. He is the author of  Genetics and Reductionism: A Primer (Cambridge, 1998), Molecular Models of Life (MIT, 2004), Biodiversity and Environmental Philosophy (Cambridge, 2005), Systematic Conservation Planning (with Chris Margules; Cambridge, 2007); “Doubting Darwin? Creationist Designs on Evolution” (Blackwell, 2007); and “Environmental Philosophy” (Wiley, 2012). He is the editor of fifteen works in the philosophy of science and the author of more than 200 scientific and philosophical articles.

To register for this program, please visit https://www.aibs.org/events/leadership/using-gene-drives-to-counter-zika.html .

The American Institute of Biological Sciences is a non-profit scientific organization working to provide decision-makers with timely, reliable, and vetted information. The organization does this independently and in partnership with its membership and business partners. To learn more about AIBS and its programmatic initiatives in science policy, education, scientific publishing, and scientific peer advisory and review services, please visit www.aibs.org.