“Scientists at Washington University School of Medicine in St. Louis have identified antibodies capable of protecting against Zika virus infection, and located the precise spot on the Zika virus that the antibodies recognize. The work is a significant step toward developing a vaccine, better diagnostic tests and possibly new antibody-based therapies. Shown is an image of Zika virus captured via cryo-electron microscope.”
From the Washington University School of Medicine. “Scientists at Washington University School of Medicine in St. Louis have identified antibodies capable of protecting against Zika virus infection, a significant step toward developing a vaccine, better diagnostic tests and possibly new antibody-based therapies. The work, in mice, helps clarify recent research that also identified protective Zika antibodies but lacked important details on how the antibodies interact with the virus.
In a study published July 27 in Cell, the researchers identified the precise spot on the virus that the antibodies recognized, information that could be used to develop a vaccine against Zika. The antibodies bound exclusively to Zika and not to related viruses, which means they are specific enough to be used in diagnostic tests.
“Importantly, some of our antibodies are able to neutralize African, Asian and American strains of Zika virus to about the same degree,” said Daved Fremon, PhD, a professor of pathology and immunology and a co-senior author on the paper. A vaccine designed to elicit similar antibodies might be able to protect people from Zika strains worldwide.
Fremont, co-senior author Michael Diamond, MD, PhD, and colleagues identified six antibodies that bound strongly to Zika virus and used a technique called X-ray crystallography to zero in on the binding site. They locked the virus and the antibodies into place together – or crystallized them – and visualized the adjacent structures by bouncing X-rays off them. The two most protective antibodies bound to the same region of the viral envelope protein that covers the surface of the virus.
“We think that this piece of the viral envelope protein alone would be able to elicit a protective immune response to Zika,” Fremont said, referring to the possibility of making a vaccine from an engineered viral protein rather than the whole virus.
Vaccines made from live, weakened viruses are common and effective, but can’t be given to pregnant women. Pregnancy suppresses a woman’s immune system, so a weak virus that safely immunizes most people could make pregnant women ill. In the case of Zika – where viral infection of pregnant women can cause devastating birth defects or miscarriage – a live-virus vaccine would be unusable, but a protein-based vaccine could be a lifesaver.