Journal
VACCINE
Volume 40, Issue 26, Pages 3655-3663Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.vaccine.2022.05.007
Keywords
COVID-19; Subunit vaccine; TLR9 adjuvant; Virus neutralization; Corbevax
Categories
Funding
- Robert J. Kleberg Jr. and Helen C. Kleberg Foundation, USA
- Fifth Generation, Inc. (Tito's Handmade Vodka), USA
- National Institute of Health-National Institute of Allergy and Infectious Diseases (NIH/NIAID), USA [AI14087201]
- Baylor College of Medicine
- Texas Children's Hospital Center for Vaccine Development Intramural Funds, USA
- JPB Foundation, USA
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In this study, a yeast-produced SARS-CoV-2 RBD subunit vaccine candidate formulated with aluminum hydroxide (alum) and CpG deoxynucleotides was evaluated in preclinical studies using mice. The results showed that the RBD/alum + CpG vaccine induced a stronger cellular immune response and could neutralize various variants of SARS-CoV-2.
We conducted preclinical studies in mice using a yeast-produced SARS-CoV-2 RBD subunit vaccine candidate formulated with aluminum hydroxide (alum) and CpG deoxynucleotides. This formulation is equivalent to the Corbevax (TM) vaccine that recently received emergency use authorization by the Drugs Controller General of India. We compared the immune response of mice vaccinated with RBD/alum to mice vaccinated with RBD/alum + CpG. We also evaluated mice immunized with RBD/alum + CpG and boosted with RBD/alum. Mice were immunized twice intramuscularly at a 21-day interval. Compared to two doses of the /alum formulation, the RBD/alum + CpG vaccine induced a stronger and more balanced Th1/Th2 cellular immune response, with high levels of neutralizing antibodies against the original Wuhan isolate of SARS-CoV-2 as well as the B.1.1.7 (Alpha), B.1.351 (Beta), B.1.617.2 and (Delta) variants. Neutralizing antibody titers against the B.1.1.529 (BA.1, Omicron) variant exceeded those in human convalescent plasma after Wuhan infection but were lower than against the other variants. Interestingly, the second dose did not benefit from the addition of CpG, possibly allowing dose-sparing of the adjuvant in the future. The data reported here reinforces that the RBD/alum + CpG vaccine formulation is suitable for inducing broadly neutralizing antibodies against SARS-CoV-2, including variants of concern. (C) 2022 The Authors. Published by Elsevier Ltd.
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