Zika virus is transmitted by the Aedes aegypti mosquito and can cause a mild illness in otherwise healthy adults. But when pregnant women are infected with Zika virus, the pathogen can pass to their fetus, and may lead to birth defects. Scientists have now discovered an unusual antibody that has a powerful neutralizing effect against Zika, which can eliminate infections so well in mouse models of the disease, the virus becomes undetectable. The findings center on an ultrapotent immunoglobulin M (IgM) antibody, which was isolated from the blood of a pregnant Zika patient, and have been reported in Cell.
While Zika virus is not causing as many infections as it did at the height of the Zika epidemic in 2015, it is still circulating in many countries at low levels, noted co-senior study author Dr. Sallie Permar, the chair of pediatrics at Weill Cornell Medicine, among other appointments. Permar noted that it's crucial for us to be ready for another Zika outbreak.
Right now, there are still no vaccines or treatments that have been approved for Zika infections. This antibody could change that, noted Permar. It might potentially be used to lower the levels of Zika virus in the blood of pregnant, infected individuals, or it may be a preventive treatment that could help reduce the likelihood of infection for people who are at risk during an active outbreak.
This work began in 2015, when study co-authors Dr. Reynaldo Dietze and Dr. Camila Giuberti, both from the Federal University of Espίrito Santo, began obtaining blood samples from Zika patients. They were focused on infected people who had given birth to healthy children, because they suspected that those people also carried antibodies that stopped the virus from moving to the fetus.
One patient in particular gave birth to a healthy baby, even while Zika virus was detectable in their blood for an especially long time - about two months. The researchers found that the B cells in this person were generating a potent IgM antibody that could stop the virus from infecting cells.
The antibody, called DH1017.IgM, was a surprise because it gets produced early on in an infection and is typically a weaker antibody that is less effective than antibodies producted later. But it also has five molecular arms, and more than one of them can bind to the virus at once.
This antibody may also be effective against other viruses. The researchers have to do more work to test its efficacy and safety, and Permar emphasized that any human trials for this therapeutic have to include pregnant poeple.
"Pregnant people are the exact population that needs vaccines or immunotherapies for Zika," she said. "It's crucial to get anti-Zika vaccines and therapies that are safe in pregnancy rolled out as soon as there is evidence of an outbreak."
Sources: Weill Cornell Medical College, Cell
