COVID-19 vaccine development: the quest to dethrone the evil King Coronavirus

We are at a decisive moment in history. With the rise of the novel coronavirus SARS-CoV-2 and its devastating toll, the scientific and medical communities must act together to stop COVID-19 disease. It will take a massive, coordinated effort to better understand the virus and how it spreads, develop and deploy tests to tell whether someone is or has been infected, and create and disseminate vaccines and treatments. These are daunting tasks with many unknown factors and biological, socioeconomic, and logistical barriers. However, leaders in pharma, biotech, and academia are forming cross-industry collaborations to overcome these obstacles, rapidly generating knowledge, tests, vaccines, and treatments with support from government and funding organizations to accelerate the process.

To remove SARS-CoV-2's crown, we need to act quickly to develop and widely disseminate novel vaccines. Due to the tendency of viruses to mutate into new strains, the varying effects of vaccines on individuals, the existence of several viable vaccine types, manufacturing limitations, and difficulties in providing access to all, creating a single vaccine will not be enough; we must design, manufacture, and deliver multiple vaccines globally.

The vaccine development landscape covers a range of platforms, including new vaccines based on already-licensed technology and next-generation approaches that may be faster to develop or more flexible to modify. Successful vaccine candidates must be rapidly developed, manufactured at large scale, readily distributed and adopted, and made broadly accessible (Thanh Le et al. 2020). While the normal vaccine development pathway can take over 10 years, we do not have that kind of time. Therefore, collaborative efforts are underway to create novel, greatly accelerated vaccine development paradigms, which begin with the design of the vaccine technology, advance into preclinical and clinical studies, and proceed to cGMP manufacturing at scale—faster than ever before.

SARS-CoV-2 virion, with red crown-like surface proteins. "Novel Coronavirus SARS-CoV-2" image reused from NIAID per CC BY 2.0.

Meet the vaccine contenders

There is an unprecedented global effort underway to develop new weapons that attack the virus. As of August 20, 2020, 41 vaccines had advanced to preclinical studies and clinical trials (check RAPS COVID-19 Vaccine Tracker for the most up-to-date information). The growing number of vaccines in all stages of development (>90) are spread across at least four vaccine types: virus vaccines, viral vector vaccines, protein-based vaccines, and nucleic-acid vaccines (Callaway 2020a). All vaccines are based on the body's ability to recognize a foreign antigen (in this case, either the whole virion or a piece of it that helps it enter cells—the spike or S protein) and build immunity. Vaccine types differ by the material delivered and means of delivery into the body, speed of development, testing requirements, ability to mass-produce, and efficacy.

Models of a SARS-CoV-2 virus and a surface spike protein.
"Novel Coronavirus SARS-CoV-2 Spike Protein" image used from NIAID per CC BY 2.0.

Virus vaccines

Many existing vaccines, such as the seasonal flu vaccine, consist of inactivated or live but weakened forms of the virus that still express antigens that elicit an immune response. To make a weakened or "live attenuated" SARS-CoV-2 virus, human or animal cells are infected with SARS-CoV-2 in its native form and serially passaged until the virus mutates to a less potent form. Alternatively, directed weakening mutations can be introduced using genetic engineering techniques. Heat or chemicals are used to make a fully inactivated virus, but large amounts of live virus are needed as starting material. The good news is that these straightforward processes have already been used for quite a few licensed human vaccines, and there is a robust vaccine production infrastructure already in place (Amanat and Krammer 2020). The downsides are that infectious SARS-CoV-2 needs to be handled, it takes some time to generate the attenuated virus and confirm antigen integrity, and extensive safety testing is required—more so than for other vaccine types. However unlikely, there is still potential for infection in those who receive the vaccine.

Viral vector vaccines

A potentially safer option is to use a different, genetically engineered virus as a vessel to deliver SARS-CoV-2 genes, including the S protein. A replicating viral vector infects cells and makes them produce more engineered virus without harming the cells, ultimately delivering that S protein to antigen-presenting cells, which kickstarts the immune response. There is a catch: sometimes, people have already built up immunity to the viral vector; depending on the chosen vector, the effectiveness of the vaccine could be reduced, and booster shots might be needed to confer longer-term immunity. This also applies to nonreplicating viral vectors that travel directly to antigen-presenting cells without being multiplied by other cells first. Importantly, no infectious coronavirus is needed to create the vector, and there is a good deal of preclinical and clinical evidence that this approach works for other emerging viruses.

Protein-based vaccines

Instead of building immunity using an antigen like the S protein of an actual coronavirus or a newly expressed S protein delivered by a viral vector, one form of protein-based vaccines directly exposes fragments of the S protein's receptor binding domain to antigen-presenting cells. Protein-based vaccines rely on recombinant protein production using, for example, a mammalian cell culture-based expression system. One can take advantage of this platform's flexibility to create fusion proteins of additional subunits that will activate a range of immune cell types for a stronger immune response (Liu et al. 2020; Kalita et al. 2020). The first multitope peptide-based vaccine has already begun clinical trials. The use of novel delivery devices can also improve immunogenicity; a microneedle array system was used to intracutaneously deliver a trimeric recombinant subunit vaccine to mice, causing a more robust humoral response than the same vaccine delivered using a traditional subcutaneous injection (Kim et al. 2020).

Once proven safe and effective, a high yield of recombinant protein would be needed to vaccinate a large population, which might be difficult with a limited global production capacity (Amanat and Krammer 2020). Also, the integrity of the recombinant proteins will need to be confirmed before use, as protein products can denature if the storage conditions are not ideal and will expire. Another form of protein-based vaccines uses just the shell of SARS-CoV-2 virions—without the genetic material that is needed for infectivity—to trigger a stronger immune response. However, these virus-like particles may be more difficult to manufacture (Callaway 2020a).

Nucleic-acid vaccines

Producing DNA and RNA vaccines involves synthesizing a plasmid or piece of messenger RNA encoding the S protein. Modes of delivery of the engineered construct into muscle or skin cells include electroporation or jet injection (for DNA) and injection of lipid-encapsulated RNA. Nucleic-acid vaccines have several advantages that make them appropriate for responding to COVID-19 (Smith et al. 2020). After a viral genome is sequenced, the production of candidate vaccine constructs can be completed in a matter of days. DNA vaccine manufacturing is significantly faster, less expensive, and safer than other vaccine types, and is more easily scaled up (Amanat and Krammer 2020). DNA is very stable, making it suitable for deployment and stockpiling. However, no licensed vaccines thus far use this technology, so regulatory and infrastructure hurdles may slow down the process.

Bypassing the need for DNA to RNA transcription, RNA vaccines are directly translated into protein, without the risks of incorporation into the genome or insertion-induced mutagenesis, as mRNA is naturally degraded after protein expression (Liu et al. 2020). These vaccines can even contain mRNA encoding multiple coronavirus antigen targets to stimulate a potent immune response. However, this immune response is a double-edged sword; while high immunoreactivity kills more coronavirus, it also damages host tissues. Moderate or severe immune reactions have been observed in a phase 1 clinical trial (Wang, Kream, and Stefano 2020). As with DNA vaccines, large-scale manufacturing of RNA vaccines is immediately feasible and would enable rapid production for vaccination of mass populations.

Allies in the fight

As time is of the essence, collaborations in vaccine development are crucial to halting the coronavirus. Knights in shining armor are banding together to develop novel nucleic-acid vaccines. Takara Bio Inc. has announced a partnership with Osaka University and AnGes Co., Ltd. to manufacture and test a platform involving a DNA plasmid vaccine and jet injection delivery device, which is currently being evaluated in preclinical studies. The DNA plasmid technology was developed by Professor Ryuichi Morishita (Osaka University Graduate School of Medicine, Clinical Gene Therapy) and AnGes. AnGes' track record of commercializing human growth factor therapeutic products using DNA manufacturing technology, including the launch of Colategen in 2019, has helped the new technology quickly transition from preclinical to clinical trials (Co-development of DNA vaccine for new coronavirus infectious disease (COVID-19) by AnGes and Osaka University: Listed in the list of vaccine development organizations published by WHO (World Health Organization), 2020). As of July 22, 2020, AnGes and Osaka University have completed a low-dose intramuscular vaccination phase 1/2 clinical trial at Osaka City University Hospital, and they are currently conducting the next trial using high doses of the vaccine (DNA vaccine for new coronavirus infectious disease ( COVID-19 ) : Phase 1/2 clinical trial Low dose vaccination completed, 2020).

Ultimately, the vaccine will be delivered using Daicel's new Actranza Lab administration device, which uses an accelerant to propel the vaccine into the skin, an organ that contains more immunocompetent cells than muscle. Daicel reports that their device can improve gene expression efficiency over conventional intramuscular delivery using a needle, and it may also increase antibody production (DAICEL Participates in the Joint DNA Vaccine Development Against the New Coronavirus Conducted by Osaka University and AnGes, Inc. with Our Novel Drug Delivery Device, "Actranza^TM lab." Technology, 2020).

Plasmid DNA can be manufactured in large quantities quickly. On Takara Bio's end, the vaccines would be produced in their main GMP facility in West Japan. This one-stop, integrated manufacturing facility houses three independent areas for plasmid DNA (and recombinant protein), virus, and cell processing. Each area has an independent airflow pipeline, material flow, vaporized hydrogen system for decontamination, and personnel team. They are also equipped with independent QC laboratories and dedicated facilities for cell banking. Since the independent processing areas are all under one roof, the facility can operate with high efficiency and zero contamination.

Takara Bio Inc.'s award-winning GMP Center for Gene and Cell Processing.

President and CEO of Takara Bio Inc. Koichi Nakao is confident they can produce vaccines for all clinical trials, and if Japan's health ministry approves a production and sales license this fall, they can make 200,000 more this year for clinical use by early 2021 (Takara Bio drives Japan's quest for a coronavirus vaccine - Nikkei Asian Review, 2020). Takara Bio Inc. expects to be able to mass-produce the vaccine, which will contribute to the loosening of restrictions in Japan and around the world. Putting the pieces in place now will allow us to respond faster to SARS-CoV-2 antigenic drifts/shifts and future infectious disease outbreaks.

Standing together to defeat the king

Many technologies, including other unique vaccines and antibody therapies not mentioned here, are being explored and tested for their ability to bring our shared challenger to its knees. The WHO has proposed a Solidarity Vaccine Trial with an adaptive design in the hopes of accelerating testing and adoption of more vaccines than possible with a traditional design (Callaway 2020b). The NIH is also thinking big with its industry partnership aiming to coordinate vaccine and drug development. The Coalition of Epidemic Preparedness, a nonprofit funding agency, is supporting efficacy trials and manufacturing costs for nine vaccines. The few vaccine developers that will get their products approved and scaled up will set the stage for other developers to take their products through safety and efficacy trials, licensing, and production under a regulatory authority.

An apoptotic cell (green) infected with SARS-COV-2 virus particles (purple).
"Novel Coronavirus SARS-CoV-2" image used from NIAID per CC BY 2.0.

Takara Bio is proud to be on the front line in the fight to defeat the coronavirus by enabling innovative vaccine development and better detection through the application of our products and technologies. Our significant contribution to the effort includes our support of other groups' research, development, and product manufacturing. We provide researchers with the tools they need to not only outsmart this virus but also to enrich the study and development of technologies in other areas of human health. We are honored to join the larger, global quest to find ways of building partnerships and networks that facilitate the control of COVID-19 and better prepare us for those inevitable future challengers.

References

Amanat, F. & Krammer, F. Perspective SARS-CoV-2 Vaccines: Status Report. Immunity 52, 583–589 (2020).

Callaway, E. The race for coronavirus vaccines: a graphical guide. Nature 580, 576–577 (2020a).

Callaway, E. Scores of coronavirus vaccines are in competition - how will scientists choose the best? Nature (2020b). doi:10.1038/d41586-020-01247-2

Co-development of DNA vaccine for new coronavirus infectious disease ( COVID-19 ) by AnGes and Osaka University : Listed in the list of vaccine development organizations published by WHO ( World Health Organization ). at <https://www.anges.co.jp/pdf.php?pdf=uXX0t6llGsGmKyCEGVjNaDSwbUdNINeA.pdf>

DAICEL Participates in the Joint DNA Vaccine Development Against the New Coronavirus Conducted by Osaka University and AnGes, Inc. with Our Novel Drug Delivery Device, "Actranza™ lab." Technology. at <https://www.daicel.com/en/news/assets/pdf/00000815-1.pdf>

DNA vaccine for new coronavirus infectious disease ( COVID-19 ) : Phase 1/2 clinical trial Low dose vaccination completed. at <https://www.anges.co.jp/pdf.php?pdf=Ip2CnBEXdD3U3Re7piAoNXiiDhiM9r6f.pdf>

Kalita, P., Padhi, A. K., Zhang, K. Y. J. & Tripathi, T. Design of a peptide-based subunit vaccine against novel coronavirus SARS-CoV-2. Microb. Pathog. 145, 104236 (2020).

Kim, E. et al. Microneedle array delivered recombinant coronavirus vaccines: Immunogenicity and rapid translational development. EBioMedicine 55, 102743 (2020).

Liu, C. et al. Research and Development on Therapeutic Agents and Vaccines for COVID-19 and Related Human Coronavirus Diseases. ACS Cent. Sci. 6, 315–331 (2020).

Smith, T. R. F. et al. Immunogenicity of a DNA vaccine candidate for COVID-19. Nat. Commun. 11, 2601 (2020).

Takara Bio drives Japan's quest for a coronavirus vaccine - Nikkei Asian Review. at <https://asia.nikkei.com/Spotlight/Coronavirus/Takara-Bio-drives-Japan-s-quest-for-a-coronavirus-vaccine>

Thanh Le, T. et al. The COVID-19 vaccine development landscape. Nature 19, 305–306 (2020).

Wang, F., Kream, R. M. & Stefano, G. B. An evidence based perspective on mRNA-SARS-CoV-2 vaccine development. Med. Sci. Monit. 26, e924700-1–e924700-8 (2020).