Scientists from the University of Maryland School of Medicine have identified seven proteins in the Zika virus that could be to blame for the birth defects linked to the pathogen.
The researchers are among scores around the world trying to develop a vaccine and other treatments for the virus, which causes neurological problems in children and adults. To do this, they are trying to understand how the virus works.
Until now, scientists didn't know which Zika proteins were causing health disorders and how they lead to disease in the body.
"The mechanism of this virus has been a real mystery," Richard Zhao, a professor of pathology and the lead researcher on the study, said in a statement. "These results give us crucial insight into how Zika affects cells. We now have some really valuable clues for future research."
The University of Maryland research, published Monday in the journal Proceedings of the National Academy of Sciences, provides the first comprehensive look at the Zika virus genome, or the genetic material that makes up a cell or organism, the scientists said.
Zika is known to cause the birth defect microcephaly in the fetuses of pregnant women infected by the virus. Babies with the condition are born with small brains and heads and struggle to survive.
Zika also is believed to cause problems for some adults, such as vision issues and Guillain-Barre syndrome, a nervous system disorder that can lead to temporary paralysis. Researchers also are beginning to believe that even babies born without microcephaly may suffer problems after birth.
Zhao said the researchers began investigating the genome last year, as Zika began to spread rapidly around the world.
"This virus was discovered very early, in 1947, but nobody really paid attention," he said in an interview. "We are really running against time because the virus spreads fast."
There were 4,809 reported cases of Zika in the United States as of Dec. 28 and 34,973 in all U.S. territories, according to the U.S. Centers for Disease Control and Prevention. A large number of cases were diagnosed in Puerto Rico.
There were 161 confirmed cases in Maryland, according to the Maryland Department of Health and Mental Hygiene.
The research involved separating each of the virus' 14 proteins and small peptides from the overall virus. Zhao then exposed fission yeast cells to each of the 14 proteins, to see how the cells responded. Seven of the proteins harmed or damaged the yeast cells in some way. Some inhibited their growth, while others damaged or killed the cells.
Zhao has used fission yeast to study other disorders, including HIV and the barley yellow dwarf virus, a plant disease that causes billions of dollars in crop damage every year throughout the world. Originally used to make beer, the yeast has been used to test in recent years how pathogens affect cells.
The CDC said last week that while much progress has been made, the fight against Zika is not over.
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There are experimental Zika vaccines being tested in people, and it is believed other human trials will soon start.
"Fighting Zika is the most complex epidemic response CDC has taken on, requiring expertise ranging from pregnancy and birth defects to mosquito control, from laboratory science to travel policy, from virology to communication science," CDC Director Dr. Tom Frieden said in a statement. "CDC experts in every field will continue to protect women and their families from the devastating complications of this threat."
The next step for Zhao and his researchers is to understand more about how the seven proteins work in humans. They will look at whether some proteins are more damaging than others, or if they all work together.
Zhao is now beginning research on how the virus interacts with rat and human cells, in collaboration with one of the study's co-authors, J. Marc Simard, a professor of neurosurgery at the University of Maryland School of Medicine. Another co-author is Robert C. Gallo, director of the Institute of Human Virology there.
Baltimore Sun reporter Scott Dance contributed to this article.