- a targeted subunit protein vaccine, developed by the Doherty Institute
- an mRNA vaccine, developed by the Monash Institute of Pharmaceutical Sciences (MIPS)
- a needle-free DNA vaccine, developed by the University of Sydney.
- Until now, vaccine candidates, such as those developed by the University of Queensland and the University of Oxford, have generally used the entire spike protein as a target. The spike is a large protein found on the surface of SARS-CoV-2, the virus that causes COVID-19.A region at the tip of the spike called the “receptor-binding domain” enables the virus to establish itself by binding to our cells and causing infection.Instead of vaccinating against the “whole” spike protein, our approach is unique in that it uses the receptor-binding domain tip.
The subunit protein vaccine contains the receptor-binding domain from SARS-CoV-2 as the antigen, or target. Exposing our immune system to this protein is intended to create antibodies that generate immunity against this part of the virus, protecting us if we encounter SARS-CoV-2 in the future.
For the mRNA vaccine, rather than injecting the protein itself, a short piece of the genetic material from the virus (mRNA) provides a blueprint to make the receptor-binding domain. So this vaccine also targets the receptor-binding domain to induce an immune response, although the process is different.
- The third COVID-19 vaccine candidate uses DNA technology. A DNA-based vaccine works in a similar way to an mRNA vaccine. By producing the viral antigen inside us, mRNA and DNA vaccines teach our immune system to recognise the antigen should the virus invade in the future.DNA vaccines have been under development for roughly the past 20 years. While they’re safe, their effectiveness remains in question. So the University of Sydney scientists are rethinking the way they’re delivered.The previous DNA vaccines relied on a standard needle and syringe delivery, but the University of Sydney’s innovative approach uses a needle-free device. This method will deliver the vaccine using a “liquid jet” to penetrate our skin.
Needle-free delivery improves the distribution of the DNA vaccine deeper into the injected site, which can improve the vaccine’s effectiveness.