An antibody “cocktail” prevents zika infection in primates

An antibody “cocktail”

An antibody "cocktail" promises to provide effective, if temporary, protection against the Zika virus. Zika can cause devastating neurological birth defects, including microcephaly, a condition in which the brain and skull are underdeveloped.

David Watkins, a professor of pathology with the University of Miami Miller School of Medicine, said, a blend of three potent antibodies completely prevented Zika infection in a group of four lab monkeys.

Regular injections of these antibodies potentially could provide vital protection to pregnant women either living in or traveling to areas where Zika is widespread.

"I would say if you were to give a woman in the first trimester an injection and then another injection at the middle of the second trimester, that would suffice" to protect her unborn child from Zika throughout the pregnancy, Watkins said.

antibody protection against a pathogen

Researchers said, the new study provides important evidence that an antibody-based therapy for Zika is potentially feasible. This cocktail is not a Zika vaccine. Vaccines teach the immune system to produce its own antibody protection against a pathogen.

This approach belongs to a new wave of immunology called passive immunotherapy. In which people injected with pre-made antibodies that provide immediate and direct protection against viruses.

Unfortunately, these antibodies have a short half-life, living only weeks or months in the bloodstream before they wear out. People must receive regular injections of the antibodies to maintain their immunity, since their own immune system never learns how to make the antibodies.

Antibodies work against Zika and other viruses by blocking their entry into human cells. These proteins will stick to a virus and prevent it from entering the cells of that person. That"s critical because a virus can"t make copies of itself outside of a cell. It needs to get inside a cell to replicate and spread.

For this experiment, Watkins and his colleagues collected 91 different antibodies produced by a Zika-infected patient from Colombia. They then selected three specific antibodies that seemed most potent against Zika, and cloned enough copies of the antibodies for use in injections.

Researchers injected the antibody trio into four lab monkeys, and a day later they exposed Zika virus. None of the monkeys developed Zika infection during three weeks of observation, but four control monkeys exposed to the same strain of Zika did become infected with the virus.

Further testing in pregnant primates will be needed before human testing can occur, the researchers said. And, animal findings frequently don"t produce similar results in humans.

However, Watkins said, "cautiously optimistic" that the antibody cocktail will be safe to both mother and unborn child.

More information: [Science Translational Medicine]