Wednesday, May 26, 2021

Things To Come? The Ebola Threat And New Vaccine Design Unveiled

Scientists unveil new Ebola virus vaccine design

Scientists at Scripps Research have unveiled a new Ebola virus vaccine design, which they say has several advantages over standard vaccine approaches for Ebola and related viruses that continue to threaten global health.

In the new design, described in a paper in Nature Communications, copies of the Ebola virus outer spike protein, known as the glycoprotein, are tethered to the surface of a spherical carrier particle. The resulting structure resembles the spherical appearance of common RNA viruses that infect humans--and is starkly different from the snake-like shape of the Ebola virus.

The scientists say the design is intended to stimulate a better protective immune response than standard vaccine approaches, which often expose the immune system to individual glycoproteins rather than realistic-looking virus particles.

In designing the vaccine, the researchers also modified the outer spike protein to be more stable than the normal, "wild-type" version found in actual Ebola virus. In tests in mice and rabbits, they showed that this stabilized version elicited virus-neutralizing antibodies more strongly than the wild-type glycoprotein used in prior Ebola vaccine approaches.

Here, we did a step-by-step investigation of glycoprotein stability and how that affects the vaccine's ability to elicit antibodies. In the end, we were able to develop a really promising vaccine design."

Jiang Zhu, PhD, Associate Professor, Department of Integrative Structural and Computational Biology, Scripps Research Institute

Zhu is the inventor of the vaccine.

Ebola virus is endemic in various African bat species and can jump to humans, causing outbreaks of hemorrhagic fever with high mortality rates. The largest known outbreak of occurred in West Africa during 2013-2016, killing more than 11,000 people.

About two decades ago, Canadian researchers developed a vaccine against Zaire ebolavirus, more commonly known as Ebola virus. The vaccine, which was later licensed to a major pharma company and is called rVSV-ZEBOV, uses a live virus--vesicular stomatitis virus--which has been modified to include the gene for the Ebola virus glycoprotein.

When injected, the rVSV-ZEBOV vaccine infects cells and produces copies of the glycoprotein, eliciting an immune response to protect against future exposure to Ebola virus. Tests in Africa amid the aforementioned outbreak suggested it worked well and it was approved by the Food and Drug Administration in late 2019. However, those tests lacked placebo groups and other standard features of typical large-scale phase-III trials. Thus, questions remain on true efficacy.

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