Novel vaccine platform for MERS could be applicable to COVID-19

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In 2015, Korea was struck by an outbreak of MERS, a disease caused by a coronavirus the same family of viruses that also caused COVID-19. Recently, a research team led by Keum Gyo-chang and Bang Eun-kyoung (Korea Institute of Science and Technology, KIST; Seoul, South Korea) and Nam Jae-Hwan (Catholic University of Korea, CUK; Seoul, South Korea) developed a novel vaccine platform using RNA-based adjuvants for the MERS coronavirus (MERS-CoV).

Protein-based vaccines are safe adjuvants, however their low stability prevents a sufficient immune response in antibody-producing cells. Therefore, a highly stable adjuvant is required for a more balanced immune response.

The new vaccine platform comprises single‐stranded RNAs (ssRNA) as an adjuvant derived from the cricket paralysis virus, and a zinc/dipicolylamine complex as a coordinative phosphate binder and a stabilizer of ssRNA adjuvants. To create the vaccine, they added and a spike protein of MERS-CoV, used by the virus to invade host cells. This was then administered to a group of mice.

Following a single inoculation, the vaccine was demonstrated to have a 100% protective efficacy against lethal doses of the virus. It promoted effective recognition and improved activation of antigen‐presenting cells, leading to better induction of neutralizing antibodies. Upon testing in macaque monkeys, MERS-CoV infection was suppressed through the induction of high neutralizing antibodies.

Nam Jae-Hwan (CUK, Korea) explained: “the nucleic acid (DNA or RNA)-based vaccines that have recently been reported have not previously been produced as vaccine products and have not gone through large-scale clinical trials. In contrast, the protein-based vaccine is mainly used vaccine platform. In this study, we added RNA as adjuvant to protein vaccine whose safety has already been proven. We expect that this new vaccine platform will enable the development of a safe vaccine.”

The results of this research establish that, when mixed, ssRNA adjuvant and zinc/dipicolylamine complex stabilizer can be applied to many vaccine types, meaning that they could potentially be utilized for development of a vaccine for COVID-19.

Keum Gyo-chang (KIST, Korea) stated: “this RNA adjuvant formulated protein vaccine, which has shown efficacy against the MERS virus, has the advantage of rapid application to the development of a vaccine for COVID-19, which is caused by the same type of virus that causes MERS.”

Nam Jae-Hwan and his research team at CUK are currently developing a vaccine against the COVID-19 virus and a vaccine for severe fever with thrombocytopenia syndrome using this new vaccine platform.

Sources: Park HJ, Bang EK, Hong JJ et al. Nanoformulated single‐stranded RNA‐based adjuvant with a coordinative amphiphile as an effective stabilizer: inducing humoral immune response by activation of antigen‐presenting cells. Angew. Chem. Int. Ed. (2020); www.eurekalert.org/pub_releases/2020-05/nrco-krt050620.php

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