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University Halts Covid-19 Vaccine Trials

Syringes for disposal

(alexroma, Pixabay)

11 Dec. 2020. An Australian university is stopping development of a vaccine to prevent Covid-19 infections due to antibodies from the vaccine that interfere with HIV tests. University of Queensland and its partner drug maker CSL announced its decision, even as the vaccine shows promise in an early-stage trial.

The Queensland-CSL vaccine, code-named v451, uses a technology from the university’s labs known as molecular clamp that stabilizes the target protein for an effective response from the immune system. This molecular clamp fuses with host cells before they can enter and infect host cells. Proteins that promote this fusion process are often candidates for vaccine design, since they attract a strong immune response that neutralizes viruses, and also provide more binding sites for antibodies before fusing with host cells.

The early-stage trial of v451 enrolled 216 healthy volunteer participants testing the vaccine’s safety and ability to generate an immune response. Queensland reports participants show no serious adverse effects from the injections, and the vaccine elicits a strong immune response. Part of that response, however, are antibodies directed against a protein called gp41 that binds with other proteins as part of the HIV infection process.

The university says tests for HIV infections look for the presence of gp41 proteins, and the magnitude of the vaccine’s response against gp41 was not expected. Thus, people with HIV infections receiving v451 could also produce false-positive HIV tests. Based on these findings, the university and CSL decided that the vaccine could not be offered to broad populations, severely limiting its usefulness.

And, as a result, CSL will not proceed with mid- and late-stage trials of v451. However, the university will complete the early-stage clinical trial and report complete findings in a scientific publication.

Paul Young, head of Queensland’s School of Chemistry and Molecular Biosciences and a developer of the molecular clamp technology says the vaccine could be fixed, but it would set back the project by a year, and the vaccine team could not afford that delay. “Doing so would set back development by another 12 or so months,” says Young in a university statement, “and while this is a tough decision to take, the urgent need for a vaccine has to be everyone’s priority.”

Nonetheless, Young says the early-stage results have enough promise to continue development of the underlying technology to prepare for future pandemics. “It is a safe and well-tolerated vaccine,” notes Young, “producing the strong virus-neutralizing effect that we were hoping to see. So we will continue to push forward and we are confident that with further work the molecular clamp technology will be a robust platform for future vaccine development here in Australia and to meet future biosecurity needs.”

As reported by Science & Enterprise in January 2020, Young and colleagues were among the early recipients of funding from Coalition for Epidemic Preparedness Innovations, or CEPI, to develop vaccines against the SARS-CoV-2 virus, then known as the novel coronavirus. At the time, 314 infection cases were reported worldwide.

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