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Updated: Aug 22, 2025
Evaluation of Host-Pathogen Responses and Vaccine Efficacy in Mice
Published on: February 22, 2019
Comparing the Immunogenicity and Protective Effects of Three MERS-CoV Inactivation Methods in Mice
Nayoung Kim1, Tae-Young Lee2, Hansaem Lee1
1Division of Emerging Virus & Vector Research, Center for Emerging Virus Research, Korea National Institute of Health, Korea Disease Control and Prevention Agency, Cheongju-si 28159, Korea.
Abstract:
The Middle East respiratory syndrome (MERS) is a fatal acute viral respiratory disease caused by MERS-coronavirus (MERS-CoV) infection. To date, no vaccine has been approved for MERS-CoV despite continuing outbreaks. Inactivated vaccines are a viable option when developed using the appropriate inactivation methods and adjuvants. In this study, we evaluated the immunogenicity and protective effects of MERS-CoV vaccine candidates inactivated by three different chemical agents. MERS-CoV was effectively inactivated by formaldehyde, hydrogen peroxide, and binary ethylene imine and induced humoral and cellular immunity in mice. Although inflammatory cell infiltration was observed in the lungs four days after the challenge, the immunized hDPP4-transgenic mouse group showed 100% protection against a challenge with MERS-CoV (100 LD50). In particular, the immune response was highly stimulated by MERS-CoV inactivated with formaldehyde, and all mice survived a challenge with the minimum dose. In the adjuvant comparison test, the group immunized with inactivated MERS-CoV and AddaVax had a higher immune response than the group immunized with aluminum potassium sulfate (alum). In conclusion, our study indicates that the three methods of MERS-CoV inactivation are highly immunogenic and protective in mice and show strong potential as vaccine candidates when used with an appropriate adjuvant.
Insights
Researchers developed potential vaccines for Middle East respiratory syndrome (MERS) using inactivated MERS-coronavirus (MERS-CoV). Formaldehyde-inactivated MERS-CoV with AddaVax showed strong immunogenicity and 100% protection in mice against the deadly virus.
Area of Science:
- Virology
- Immunology
- Vaccinology
Background:
- Middle East respiratory syndrome (MERS) is a severe, fatal respiratory illness caused by MERS-coronavirus (MERS-CoV).
- No approved vaccine currently exists for MERS-CoV, despite ongoing outbreaks and significant public health concerns.
- Inactivated vaccines represent a promising strategy for MERS-CoV prevention, contingent on effective inactivation methods and adjuvant selection.
Purpose of the Study:
- To assess the immunogenicity and protective efficacy of MERS-CoV vaccine candidates inactivated by three distinct chemical agents.
- To compare the immune response elicited by different adjuvants when combined with inactivated MERS-CoV.
Main Methods:
- MERS-CoV was inactivated using formaldehyde, hydrogen peroxide, and binary ethylene imine.
- Immunogenicity was evaluated by assessing humoral and cellular immune responses in immunized mice.
- Protective effects were determined through challenge studies using MERS-CoV in hDPP4-transgenic mice.
- Adjuvant efficacy was compared using AddaVax and aluminum potassium sulfate (alum).
Main Results:
- All three inactivation methods (formaldehyde, hydrogen peroxide, binary ethylene imine) effectively inactivated MERS-CoV and induced both humoral and cellular immunity in mice.
- Mice immunized with inactivated MERS-CoV vaccines demonstrated 100% protection against a lethal MERS-CoV challenge (100 LD50).
- Formaldehyde-inactivated MERS-CoV elicited a particularly strong immune response, with all mice surviving the minimum challenge dose.
- AddaVax as an adjuvant resulted in a higher immune response compared to aluminum potassium sulfate (alum).
Conclusions:
- The three chemical inactivation methods evaluated are effective for producing MERS-CoV vaccine candidates.
- These inactivated MERS-CoV vaccines are highly immunogenic and provide complete protection in a mouse model.
- The choice of adjuvant significantly impacts the immune response, with AddaVax showing superior performance over alum.
