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Researchers in St. Louis making headway against Zika virus

Researchers in St. Louis making headway against Zika virus

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Zika virus vaccine

Nicole Purcell, a lab technician in the Infectious Diseases Division, aliquots a sample of whole blood from a potential Zika vaccine study participant at the Doisy Research Center on Monday, Oct. 17, 2016, in St. Louis. The aliquotting process separates the serum plasma from the whole blood so it can be further studied to determine if the volunteer is suitable for the Zika vaccine trial. Volunteers in the study cannot have any pre-existing antibodies to the Zika virus or related mosquito-borne viruses. Photo by Chris Lee, clee@post-dispatch.com

The danger of the Zika virus lies in its ability to cross the body’s most protective barrier and cause severe birth defects in babies.

“It hits at the core of humanity,” said Indira Mysorekar, associate professor at Washington University. “It’s a formidable enemy.”

Mysorekar and her research team discovered that a drug used to treat malaria, another mosquito-borne disease, can prevent the transmission of Zika from mother to fetus in mice.

The drug, hydroxychloroquine, appears to reduce the viral load of Zika in the placenta and in the brains of baby mice, which were normal sized at birth. It did not clear the virus from the mother’s blood, indicating that the placental barrier remained protective.

The findings will have to be replicated in humans, but they offer some direction for potential treatments for pregnant women.

“We are excited because it’s a drug that’s extremely common, very cheap, available around the world and FDA-approved for pregnant women,” Mysorekar said. “Often in these studies scientists can work for decades, and they don’t necessarily translate to patient care. It’s very gratifying to potentially repurpose this drug.”

The first evidence that Zika could cross the placental barrier came in Brazil two years ago, when an unusual number of babies were born with microcephaly, or small heads. The stunted head growth caused severe brain damage, blindness and other neurological problems.

An epidemic of Zika occurred in Latin America and the Caribbean before the virus reached the U.S. last year, resulting in 218 cases contracted in Florida and six in Texas.

Most people who catch the virus have no symptoms, or mild fever, joint pain, rash and pink eye. The highest risk is for pregnant women. There have been 88 babies born in the U.S. with birth defects and eight miscarriages reported in women who caught the virus while pregnant.

Since there is no vaccine and no treatment specific to Zika, health officials urged pregnant women to limit travel and prevent mosquito bites. Research into the disease sped up across the U.S. with increased funding for Zika in the 2016 budget.

Another lab at Washington University focuses on how the body is able to fight off Zika infection to discover potential vaccines and treatments for the virus. One advantage to the study of Zika is its similarities to West Nile and dengue viruses, which have long research histories. Clinical trials on Zika drugs could start within a year pending federal approval, said Daved Fremont, professor of pathology and immunology.

The best way to stop Zika’s damage is to prevent infection. Clinical trials are underway at St. Louis University’s Center for Vaccine Development on a vaccine developed at the Walter Reed Army Institute of Research in Maryland.

The study involves close to 100 adults who received the vaccine or a placebo starting last fall. Participants who got the vaccine have developed antibodies to fight the virus, and no serious complications have been reported, said Dr. Daniel Hoft of the vaccine center.

The vaccine tested at SLU was modeled on a shot designed to fight a similar virus also spread by mosquitoes. It was developed from Zika virus that was isolated in Puerto Rico, grown in the lab and then deactivated so it cannot cause infection.

Another SLU trial taking place in Puerto Rico will compare the immune systems of people who caught the virus from mosquitoes and then recovered to people who received the Zika vaccine.

“We believe that by understanding more about what clears the infection (in the body) we can fine-tune our vaccine efforts to get a similar response,” Hoft said.

A Zika vaccine could reach the market by 2018 or 2019 if it proves safe and effective. Research teams at SLU also are trying to develop a quick and accurate test to diagnose Zika. Currently the most accurate test for Zika catches the presence of the virus only in the first week or so after infection. Another blood test that can determine if someone had Zika in the past is expensive, and it is more difficult to determine which mosquito-borne virus is the main culprit.

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