A blend of three potent antibodies completely prevented Zika infection in a group of four lab monkeys, said senior researcher David Watkins, a professor of pathology with the University of Miami Miller School of Medicine.
Regular injections of these antibodies potentially could provide vital protection to pregnant women either living in or traveling to areas where Zika is widespread, Watkins said.
Zika can cause devastating neurological birth defects, including microcephaly, a condition in which the brain and skull are underdeveloped.
“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.
“If further studies — including ones done in humans — replicate these findings, a preventative antibody cocktail could be constructed and used to temporarily protect those traveling to Zika-prone areas,” Adalja said.
This is not a Zika vaccine, Watkins noted. Vaccines teach the immune system to produce its own antibody protection against a pathogen.
Instead, this approach belongs to a new wave of immunology called “passive immunotherapy,” in which people are injected with pre-made antibodies that provide immediate and direct protection against viruses.
“What we’re doing here is simply short-cutting the vaccination,” Watkins said.
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 provide promising Zika prophylaxis
The recent Zika virus epidemic and ensuing fetal consequences caught the world off guard. Scientists are now scrambling for information on Zika virus detection, treatment, and prevention. Passive immunity provided by monoclonal antibodies offers an attractive alternative to traditional vaccines, because it can be generated relatively quickly. Magnani et al. isolated and engineered three neutralizing antibodies from a Zika-infected patient. Administration of these antibodies completely protected nonhuman primates from becoming infected with Zika virus, suggesting that such a cocktail could be used to prevent Zika infections in people.
Therapies to prevent maternal Zika virus (ZIKV) infection and its subsequent fetal developmental complications are urgently required. We isolated three potent ZIKV-neutralizing monoclonal antibodies (nmAbs) from the plasmablasts of a ZIKV-infected patient—SMZAb1, SMZAb2, and SMZAb5—directed against two different domains of the virus. We engineered these nmAbs with Fc LALA mutations that abrogate Fcγ receptor binding, thus eliminating potential therapy-mediated antibody-dependent enhancement. We administered a cocktail of these three nmAbs to nonhuman primates 1 day before challenge with ZIKV and demonstrated that the nmAbs completely prevented viremia in serum after challenge. Given that numerous antibodies have exceptional safety profiles in humans, the cocktail described here could be rapidly developed to protect uninfected pregnant women and their fetuses.