Unglycosylated Soluble SARS-CoV-2 Receptor Binding Domain (RBD) Produced in <i>E. coli</i> Combined with the Army Liposomal Formulation Containing QS21 (ALFQ) Elicits Neutralizing Antibodies against Mismatched Variants
Arasu Balasubramaniyam,
Emma Ryan,
Dallas Brown,
Therwa Hamza,
William Harrison,
Michael Gan,
Rajeshwer S. Sankhala,
Wei-Hung Chen,
Elizabeth J. Martinez,
Jaime L. Jensen,
Vincent Dussupt,
Letzibeth Mendez-Rivera,
Sandra Mayer,
Jocelyn King,
Nelson L. Michael,
Jason Regules,
Shelly Krebs,
Mangala Rao,
Gary R. Matyas,
M. Gordon Joyce,
Adrian H. Batchelor,
Gregory D. Gromowski,
Sheetij Dutta
Affiliations
Arasu Balasubramaniyam
Biologics Research and Development Branch, Structural Vaccinology Laboratory, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
Emma Ryan
Biologics Research and Development Branch, Structural Vaccinology Laboratory, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
Dallas Brown
Biologics Research and Development Branch, Structural Vaccinology Laboratory, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
Therwa Hamza
Biologics Research and Development Branch, Structural Vaccinology Laboratory, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
William Harrison
Biologics Research and Development Branch, Structural Vaccinology Laboratory, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
Michael Gan
Biologics Research and Development Branch, Structural Vaccinology Laboratory, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
Rajeshwer S. Sankhala
Emerging Infectious Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
Wei-Hung Chen
Emerging Infectious Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
Elizabeth J. Martinez
Emerging Infectious Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
Jaime L. Jensen
Emerging Infectious Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
Vincent Dussupt
Emerging Infectious Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
Letzibeth Mendez-Rivera
Emerging Infectious Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
Sandra Mayer
Emerging Infectious Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
Jocelyn King
Emerging Infectious Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
Nelson L. Michael
Center for Infectious Disease Research, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
Jason Regules
Biologics Research and Development Branch, Structural Vaccinology Laboratory, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
Shelly Krebs
Emerging Infectious Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
Mangala Rao
U.S. Military HIV Research Program, Laboratory of Adjuvant and Antigen Research, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
Gary R. Matyas
U.S. Military HIV Research Program, Laboratory of Adjuvant and Antigen Research, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
M. Gordon Joyce
Emerging Infectious Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
Adrian H. Batchelor
Biologics Research and Development Branch, Structural Vaccinology Laboratory, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
Gregory D. Gromowski
Viral Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
Sheetij Dutta
Biologics Research and Development Branch, Structural Vaccinology Laboratory, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
The emergence of novel potentially pandemic pathogens necessitates the rapid manufacture and deployment of effective, stable, and locally manufacturable vaccines on a global scale. In this study, the ability of the Escherichia coli expression system to produce the receptor binding domain (RBD) of the SARS-CoV-2 spike protein was evaluated. The RBD of the original Wuhan-Hu1 variant and of the Alpha and Beta variants of concern (VoC) were expressed in E. coli, and their biochemical and immunological profiles were compared to RBD produced in mammalian cells. The E. coli-produced RBD variants recapitulated the structural character of mammalian-expressed RBD and bound to human angiotensin converting enzyme (ACE2) receptor and a panel of neutralizing SARS-CoV-2 monoclonal antibodies. A pilot vaccination in mice with bacterial RBDs formulated with a novel liposomal adjuvant, Army Liposomal Formulation containing QS21 (ALFQ), induced polyclonal antibodies that inhibited RBD association to ACE2 in vitro and potently neutralized homologous and heterologous SARS-CoV-2 pseudoviruses. Although all vaccines induced neutralization of the non-vaccine Delta variant, only the Beta RBD vaccine produced in E. coli and mammalian cells effectively neutralized the Omicron BA.1 pseudovirus. These outcomes warrant further exploration of E. coli as an expression platform for non-glycosylated, soluble immunogens for future rapid response to emerging pandemic pathogens.
