A promising vaccine approach to induce longer-lasting protective immunity against COVID-19: NUS Medicine-Monash University study
Published: 04 Jun 2024
A scientific team from the Yong Loo Lin School of Medicine at the National University of Singapore (NUS Medicine) and Monash University, Australia, has engineered a COVID-19 vaccine that induced – in pre-clinical models – very long-lasting, protective immunity against SARS-CoV-2 virus with a single-shot immunisation.
In an on-going, four-year collaboration, the team led by Assoc Prof Sylvie Alonso, Director of the Infectious Diseases Translational Research Programme at NUS Medicine and Assoc Prof Mireille Lahoud from Monash University, Australia, leveraged on a novel vaccine platform to fuse the receptor-binding domain (RBD) from the spike protein of the SARS-CoV-2 virus to the Clec9A antibody.
The Clec9A antibody targets a specific subset of dendritic cells, a specialised type of immune cells found in tissues such as the skin, which are responsible for initiating immune responses in our body.
Upon a single shot immunisation of the Clec9A-RBD antibody construct, the team monitored the immune responses in pre-clinical models over 21 months, and found no signs of declined immunity. In contrast, it observed that the quality of the immune response (the neutralising antibody response, in particular), was associated with increased protection over time.
Messenger RNA (mRNA) COVID-19 vaccines have been reported to demonstrate peak effectiveness of 162% after three weeks, post-jab, before declining to 9% after nine months. Protection from booster doses has been reported to wane, dropping from 260% one month after the booster dose to 13% at nine months.
This new Clec9A targeting technology may potentially address the issue of waning COVID-19 vaccine immunity, and eliminate the need for repeated booster jabs, particularly for persons aged 60 years and above, medically vulnerable individuals and caregivers of medically vulnerable persons. While the effects of long COVID have been found to have respiratory, cardiovascular, digestive, motor and cognitive implications, its long-term damage on our bodies has yet to be established.
This latest breakthrough follows closely on the heels of the team’s 2022 research, published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS). Back then, it leveraged on the Clec9A targeting vaccine platform to deliver the universal influenza vaccine candidate M2e.
M2e is notoriously known to be unable to induce strong and durable immune responses. The team demonstrated that a single-shot immunisation of the Clec9A-M2e construct triggered long-lasting immune responses to effectively protect against multiple strains of the flu. It effectively removes a major bottleneck in the clinical development of M2e-based vaccine candidates.
This study was published in Molecular Therapy under Cell Press.
For more details, read the media release here.
