A CTB-SARS-CoV-2-ACE-2 RBD Mucosal Vaccine Protects Against Coronavirus Infection

Area of Science:

• * Immunology
• * Vaccinology
• * Virology

Background:

• * Mucosal vaccines are crucial for preventing respiratory virus infections by inducing IgA antibodies.
• * The SARS-CoV-2 virus poses a significant global health threat, necessitating effective vaccine strategies.

Purpose of the Study:

• * To construct and evaluate a novel protein subunit mucosal vaccine against SARS-CoV-2.
• * To assess the immunogenicity and protective efficacy of a chimeric CTB-SARS-CoV-2 ACE-2-RBD vaccine in mice.

Main Methods:

• * A fusion protein linking cholera toxin B subunit (CTB) and SARS-CoV-2 ACE-2 receptor binding domain (RBD) was engineered and expressed in E. coli.
• * The chimeric protein was purified using nickel affinity chromatography and polyacrylamide gel electrophoresis.
• * Mice were immunized via oral, nasal, and parenteral routes, and immune responses were analyzed by ELISA and neutralization assays.

Main Results:

• * A 42 kDa CTB-SARS-CoV-2 ACE-2-RBD fusion protein was successfully synthesized and purified.
• * Immunization induced durable SARS-CoV-2 specific IgG and IgA antibodies capable of neutralizing Omicron BA.1.1.
• * Vaccinated mice showed no lung tissue abnormalities, indicating protection against viral infection.

Conclusions:

• * The CTB-adjuvanted chimeric mucosal vaccine effectively elicits neutralizing antibodies against SARS-CoV-2.
• * This bacterial-synthesized vaccine shows promise for preventing respiratory virus infections.