Both of the new Melbourne vaccine candidates — one developed by the Doherty Institute and the other by Monash University — are hoped to provide a much more targeted attack than existing vaccines.They do this by focusing solely on the most dangerous area at the tip of the Covid-causing virus’s spike protein, called the receptor binding domain, or RBD.The RBD vaccines’ developers are confident they will offer greater protection, not only against Omicron, but future strains that are yet to be detected.However, the two vaccines must first succeed during a world-first joint Phase 1 trial, in which 114 Melburnians will be jabbed at the Royal Melbourne Hospital over the next three months.While Doherty scientists have developed a traditional recombinant protein vaccine, the Monash Institute of Pharmaceutical Sciences has produced Australia’s first mRNA shot.But because both target the RBD of SARS-CoV-2 — rather than the entire spike like existing vaccines — Doherty Institute director Professor Sharon Lewin believes they may offer greater protection as a future fourth jab.“There’s a number of reasons why we think they’re going to be better,” Professor Lewin said.“This vaccine targets a smaller part of the spike protein and therefore it may give you a more efficient immune response, so your immune responses isn’t wasting time on the other parts of that spike protein.Path to better Vaccine“We’ve had some very good results in the mouse models showing that the vaccines are highly immunogenic and they protect very well from infection, including from other variants.“That provides justification to go into humans but in the end we got to see how it performs a people.”During animal testing the Doherty’s protein and Monash’s mRNA vaccine induced high levels of antibodies specifically targeting the RBD, the tip of the spike protein which SARS-CoV-2 uses to attach and infect other cells.Because both are based on Covid’s Beta variant, which shares genetic mutations with Omicron, they are also more suited to combating current and future strains than first generation vaccines based on the original Wuhan virus.The Melbourne Phase 1 trial will be the first time two Covid vaccines have been examined head to head, providing a world-first chance to evaluate the traditional protein and emerging mRNA platforms against each other.The importance and difficulty in passing the initial safety tests was underlined in July 2020, when a promising University of Queensland Covid vaccine candidate was discovered to induce false-positive HIV and it’s Phase 1 trial and had to be halted.Leader of Monash Institute of Pharmaceutical Sciences’ mRNA vaccine team, Professor Colin Pouton, said he was confident the RBD jabs would be better at boosting immunity against new Covid variants, though he was desperate to see how they performed. “We actually think our vaccine is going to be better than the existing ones — not just as good as them,” Professor Pouton said.“We are really excited about getting into the clinic because we need to see that it’s working in humans.“We’re very confident, but we need to see it’s working.”The federal government provided $4.6m to accelerate the two vaccine candidates to clinical trials, and Health Minister Greg Hunt said he was pleased to see the progress which may not only secure Australia’s vaccine strategy into the future, but that of the world.“These two vaccines have the potential to solve the global problem of mutated versions of the SARS-CoV-2 virus. This is an exciting possibility,” Mr Hunt said.“I would also note the vaccines to be used in the clinical trials are being manufactured locally.”The Victorian government granted Monash University $5m through mRNA Victoria tomanufacture its vaccine in partnership with Melbourne-based company, IDT Australia.Minister for Innovation, Medical Research and the Digital Economy Jaala Pulford said Melbourne already ranked with Boston and London as a medical research centre, however the launch of the Phase 1 vaccine trial and the reality of mRNA development offered “phenomenal potential” for future breakthroughs.“This has been conceived with a view to being suitable for different variants and it is really exciting to see it moving to this next stage,” Ms Pulford said.“The day this goes into arms is going to be a really big milestone in the history of our medical sector.”With data over the past two years’ of development showing the RBD vaccines producing neutralising antibodies at levels surpassing those of currently approved “spike” vaccines, the Doherty’s Professor Dale Godfrey said he couldn’t wait to see how they performed. “We’re sort of pinching ourselves a bit. We’re almost there and there’s been so many hurdles that have popped up along the way that we’ve cleared,” he said.“We’ll probably be celebrating when first people are immunised and just wait and see what the data says.”
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