Researchers from PolyU and M.U.S.T. Collaborate in the Development of a Recombinant RBD Vaccine Against SARS-CoV-2

Coronavirus (the virus that causes COVID-19) has continued to spread across the world. Here in Hong Kong, people are confronting a third wave of outbreaks, with the number of confirmed infections surging to over 3,000 in just a few weeks. Since the early days of the outbreak, The Hong Kong Polytechnic University (PolyU) has been working with various research partners in the fight against COVID-19 through the development of different diagnostic and preventive measures. PolyU and the Macau University of Science and Technology (M.U.S.T), in collaboration with other Chinese institutions, announced today a significant breakthrough in the development of a COVID-19 vaccine. Their study is the focus of a research paper recently published in the prestigious science journal Nature, entitled “A Vaccine Targeting the RBD of the S protein of SARS-CoV-2 Induces Protective Immunity”. (link)

At the most critical step during infection, SARS-CoV-2 uses its Spike protein receptor-binding domain (S-RBD) to engage with the host cell receptor angiotensin-converting enzyme 2 (ACE2). In this study, the research team found that a recombinant vaccine comprising S-RBD could induce a potent functional antibody response in the immunised mice, rabbits and non-human primates (Macaca mulatta) as early as seven or 14 days after a single dose injection. The sera from the immunised animals blocked RBD binding to ACE2 expressed on the cell surface and neutralised infection by SARS-CoV-2 pseudovirus and live SARS-CoV-2 in vitro. Importantly, the vaccination also provided protection in non-human primates from SARS-CoV-2 challenge in vivo. Elevated RBD-specific antibodies were also found in the sera from patients with COVID-19.

Professor Kang ZHANG from the Faculty of Medicine of M.U.S.T., the corresponding author of the paper, explained, “The objective of this study was to evaluate the potential of a candidate vaccine based on the RBD domain of SARS-CoV-2. At the same time, we wanted to evaluate the appropriate dosing regime, to test its effect in generating neutralising activity against SARS-CoV-2 in the recipient animals and to determine the immune pathways involved in the generation of the immune response, so as to provide the groundwork for the design of an effective SARS-CoV-2 preventive vaccine. According to the study, the vaccine had given potent and complete protection to the vaccinated animals including monkeys. He added that “Our finding highlights the importance of the RBD domain in the SARS-CoV-2 vaccine design, which provides the rationale for the development of a protective vaccine through the induction of antibody against the RBD domain”.

According to Dr Johnson LAU, Adjunct Professor of the Department of Applied Biology and Chemical Technology of PolyU, the baculovirus expression system was chosen to express the various proteins for this study as this is a commercially feasible system and can be used to manufacture the candidate vaccine, if successful, on a commercial scale. He stated that “In this study, the research team has demonstrated that recombinant vaccines against Spike protein RBD region can effectively induce a potent immune response in the body with a good safety profile. In addition, the biotechnology method used in creating the recombinant RBD vaccine is mature and feasible in aiding mass vaccine production. It is expected to provide a practical solution to fight against COVID-19.”

Ir Professor Alexander WAI, Deputy President and Provost of PolyU, said, “We all know there is an urgency to producing an effective preventive vaccine for COVID-19. Apart from the diagnostic and preventive tools available that help to contain the virus transmission in the community, our researchers foresee the threat of further outbreaks which may only stop once a vaccine is available to everyone. With the ongoing efforts of PolyU and M.U.S.T., the recombinant RBD protein vaccine may be the best vaccine choice to combat this pandemic. It is our mission to make use of our expertise and to utilise scientific technologies for prevention and control of the virus, so as to help people to live under the ‘new normal’ of coronavirus.”

Professor Manson FOK, Dean of the Faculty of Medicine of M.U.S.T. remarked, “Our research team has faced many challenges when designing our vaccine for best effect, while keeping side effects to a minimum and relieving other production concerns. To move forward, the efficacy of the vaccine needs to be evaluated and validated in human clinical trials, which will be initiated shortly. This breakthrough in COVID-19 vaccine could not have been achieved without the concerted efforts of our researchers and we hope mass vaccination can be conducted in the nearest future.”

 

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