A promising experimental therapy that prevents Zika in monkeys does not stop the virus spreading from a pregnant mother to her fetus, researchers at the University of Miami’s Miller School of Medicine reported Tuesday in the journal, Nature Communications.
The news follows an October article in which UM scientists reported that they had stopped Zika from spreading to macaque monkeys by first injecting the primates with a mix of antibodies that had been cloned from the blood of an infected person.
Diogo Magnani, a UM scientist and lead author of both articles, said that while the experimental therapy had cleared the virus from the blood of pregnant monkeys, the antibodies could not stop Zika from crossing into the amniotic fluid and leading to fetal deaths.
“That’s a big complication,” Magnani said. “It suggests for women that got infected with Zika during pregnancy that their fetus might still be infected even though the virus is not showing up in their blood.”
The study — a collaborative effort between scientists at UM, the Scripps Research Institute, the Fiocruz Institute in Brazil and others, and funded by a grant from the Department of Defense — will now focus on developing a specific therapy to help the antibodies cross into the placenta, Magnani said.
“What we think is happening is the antibodies are not crossing the placenta in sufficient amounts,” he said. “We are now going to treat the antibodies to make sure they cross in large amounts. We’re optimistic that this can be done.”
The new findings are significant because pregnant women and their fetuses are at greatest risk from Zika because the virus can cause birth defects and neurological problems in newborns.
For now, the best way to prevent Zika is to avoid bites from an infected Aedes aegypti species of mosquito. The virus also can be contracted from having sex with an infected person.
In the latest experiment, Magnani said scientists injected 11 macaque monkeys at different stages of pregnancy with a Zika virus extracted from the urine of an infected pregnant woman at the Fiocruz Institute in Brazil, where a 2016 outbreak caused about 40 percent of pregnant women to have fetal problems, including birth defects such as microcephaly. The condition causes a baby’s head to be smaller than expected because the brain did not develop properly in the womb.
Florida became the first state in the nation to report a locally transmitted case of Zika in 2016, when the Centers for Disease Control and Prevention and the Florida Department of Health reported that mosquitoes were spreading the virus in Miami’s Wynwood neighborhood, triggering a travel advisory that warned pregnant women to avoid travel to Miami-Dade County.
Local spread of the virus also cropped up in areas of Miami Beach and Miami’s Little River neighborhood.
That year, a total of 299 pregnant women in Florida were reported to have laboratory-confirmed Zika, and four babies were born with congenital Zika syndrome, according to the state’s surveillance data.
A total of 1,469 Zika infections, most acquired by people traveling outside the country, were reported in Florida in 2016.
Zika waned in 2017, with 249 cases statewide, including 127 pregnant women and three babies born with congenital Zika syndrome. Only two local cases of Zika were reported by Florida health officials in 2017.
So far in 2018, Florida health officials have reported 29 Zika cases, including 21 pregnant women, all of them acquired by people traveling outside the state.