On Mar. 24, 2020, Dynavax Technologies and Clover Biopharmaceuticals, a China-based global clinical-stage biotechnology company, announced a research collaboration to develop a vaccine candidate to prevent COVID-19. Clover is advancing evaluation of its protein-based coronavirus vaccine candidate (COVID-19 S-Trimer) in preclinical studies. Dynavax is providing technical expertise and the companyﾒs proprietary toll-like receptor 9 (TLR9) agonist adjuvant, CpG 1018, to support this initiative.

In late-January 2020, upon knowing the genomic DNA sequence of the newly identified SARS-CoV-2 virus, which causes a disease named COVID-19, Clover scientists started designing the viral spike (S)-protein construct and completed its gene synthesis. Utilizing its patented Trimer-Tag^™ technology, Clover has produced a COVID-19 S-Trimer subunit vaccine candidate that resembles the native trimeric viral spike via a rapid mammalian cell-culture based expression system.  Having one of the largest in-house, commercial-scale cGMP biomanufacturing capabilities in China, Clover could potentially rapidly scale-up and produce large-quantities of a new coronavirus vaccine.

CpG 1018 is the adjuvant used in HEPLISAV-B® [Hepatitis B Vaccine (Recombinant), Adjuvanted], an adult hepatitis B vaccine approved by the U.S. Food and Drug Administration (FDA). Dynavax developed CpG 1018 to provide an increased vaccine immune response, which has been demonstrated in HEPLISAV-B. CpG 1018 provides a well‑developed technology and a significant safety database, potentially accelerating the development and large-scale manufacturing of a COVID-19 vaccine.

SARS-CoV-2 is a new coronavirus identified in late 2019 and belongs to a family of enveloped RNA viruses that include MERS and SARS, both of which caused serious human infections of respiratory system.  The virus, which causes a disease named COVID-19, has never before been found in humans. Since this outbreak was first reported in late-2019, the virus has infected over 334,000 people and has caused over 14,600 reported deaths (as of 23 March 2020). It has been declared a pandemic by the World Health Organization (WHO).  Currently there is no vaccine available for COVID-19.

Utilizing Trimer-Tag^™ technology, S-Trimer is a trimeric SARS-CoV-2 spike (S)-protein subunit vaccine candidate. Similar to other enveloped RNA viruses such as HIV, RSV and Influenza, SARS-CoV-2 is also an RNA virus that has a trimeric spike (S) protein on its viral envelope. The trimeric S protein of SARS-CoV-2 is responsible for binding to host cell surface receptor ACE2 and subsequent viral entry, making it the primary target antigen for vaccine development. S-Trimer resembles the native trimeric viral spike protein and is produced via a rapid mammalian cell-culture based expression system.