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Zika Virus Structural Basis Limits Vaccine Development

October 26, 2021 • 2:07 pm CDT
(Zika News)

Though the number of Zika virus infections has decreased since 2018, scientists speculate they may be due to herd immunity in some areas.

However, there is still potential for future outbreaks.

Scientists want to understand how the human immune system recognizes the Zika virus to develop preventive vaccines.

Shannon Esswein, a graduate student, and Pamela Bjorkman, a professor at the California Institute of Technology, presented new insights on how the body’s antibodies attach to the Zika virus. These insights were published in PNAS, February 25, 2021.

To study the antibody response to Zika and other flaviviruses, Esswein and Bjorkman looked at several antibodies from the blood of patients from Mexico and Brazil.

To find antibodies that recognize flaviviruses, they used a piece of the outside of the virus, called the envelope domain III protein.

Previous studies have shown the envelope domain III is an essential target of protective antibodies that fight flavivirus infections.

The researchers studied how those antibodies changed over time as they mature and became better able to stick to the Zika virus and how the antibodies cross-react with other flaviviruses, including the four types of dengue viruses.

They found that the Zika antibodies also tightly stick to and defend against dengue type 1 and weakly stick to West Nile and dengue types 2 and 4.

“The weak cross-reactivity of these antibodies doesn’t seem to defend against those flaviviruses, but also doesn’t induce ADE,” Esswein said, suggesting envelope domain III may be useful to make a safe vaccine.

They also determined structures showing how two antibodies recognize Zika and West Nile envelope domain III.

Together, the team’s experiments show how the body mounts “a potent immune response to Zika virus,” says Esswein.

Their insights into the antibodies involved in this immune response will help inform vaccine design strategy.

As of October 26, 2021, the U.S. FDA had not approved a Zika vaccine.