Immunogenicity of High-Dose MVA-Based MERS Vaccine Candidate in Mice and Camels

Area of Science:

• Virology
• Immunology
• Vaccinology

Background:

• Middle East respiratory syndrome coronavirus (MERS-CoV) is a zoonotic virus transmitted from dromedary camels to humans, causing severe pneumonia with a high mortality rate.
• Developing effective vaccines is crucial to mitigate MERS-CoV spread and impact.
• A modified vaccinia virus Ankara (MVA) vector vaccine, MVA-MERS, encoding the full-length MERS-CoV spike protein has been previously developed.

Purpose of the Study:

• To evaluate the immunogenicity of a high-dose MVA-MERS vaccine administered via prime-boost regimens in mice and camels.
• To assess the induction of antibody responses, including neutralizing antibodies, against MERS-CoV.

Main Methods:

• Mice were immunized using prime-boost strategies with MVA-wild-type (MVA-wt) and MVA-MERS.
• Camels received two doses of either phosphate-buffered saline (PBS), MVA-wt, or MVA-MERS.
• Antibody responses were quantified using ELISA and MERS pseudovirus neutralization assays.

Main Results:

• Homologous prime-boost vaccination with two high doses of MVA-MERS elicited robust antibody responses in both mice and camels.
• The induced antibodies demonstrated significant neutralizing activity against MERS-CoV.
• Pre-existing or induced anti-MVA antibodies did not impede the immune response to the MERS-CoV spike antigen.

Conclusions:

• The MVA-MERS vaccine, when administered in a homologous prime-boost regimen, effectively induces high levels of neutralizing anti-MERS-CoV antibodies in mice and camels.
• These findings support the further development of MVA-MERS as a potential vaccine for dromedary camels to reduce human MERS-CoV transmission.
• Targeting dromedary camels offers a One Health approach to control zoonotic disease spread.