Generation and Characterization of a Mouse-Adapted Makona Variant of Ebola Virus
Mable Chan1, Anders Leung1, Bryan D Griffin1,2
1Special Pathogens Program, National Microbiology Laboratory, Public Health Agency of Canada, 1015 Arlington Street, Winnipeg, MB, R3E 3R2, Canada.
Abstract:
Ebola virus (EBOV) is a zoonotic pathogen that poses a significant threat to public health, causing sporadic yet devastating outbreaks that have the potential to spread worldwide, as demonstrated during the 2013-2016 West African outbreak. Mouse models of infection are important tools for the development of therapeutics and vaccines. Exposure of immunocompetent mice to clinical isolates of EBOV is nonlethal; consequently, EBOV requires prior adaptation in mice to cause lethal disease. Until now, the only immunocompetent EBOV mouse model was based on the Mayinga variant, which was isolated in 1976. Here, we generated a novel mouse-adapted (MA)-EBOV based on the 2014 Makona isolate by inserting EBOV/Mayinga-MA mutations into the EBOV/Makona genome, followed by serial passaging of the rescued virus in suckling mice. The resulting EBOV/Makona-MA causes lethal disease in adult immunocompetent mice within 6 to 9 days and has a lethal dose (LD50) of 0.004 plaque forming units (PFU). Two additional mutations emerged after mouse-adaptation in the viral nucleoprotein (NP) and membrane-associated protein VP24. Using reverse genetics, we found the VP24 mutation to be critical for EBOV/Makona-MA virulence. EBOV/Makona-MA infected mice that presented with viremia, high viral burden in organs, increased release of pro-inflammatory cytokines/chemokines, and lymphopenia. Our mouse model will help advance pre-clinical development of countermeasures against contemporary EBOV variants.
Insights
A new mouse-adapted Ebola virus (EBOV) model, EBOV/Makona-MA, causes lethal disease in immunocompetent mice. This model, crucial for developing EBOV countermeasures, identified a key VP24 mutation enhancing virulence.
Area of Science:
- Virology
- Infectious Diseases
- Animal Models
Background:
- Ebola virus (EBOV) poses a significant global public health threat, necessitating effective countermeasures.
- Existing mouse models for EBOV often require immunocompromised animals or adapted strains for lethal infection.
- A need exists for immunocompetent mouse models using contemporary EBOV variants for pre-clinical research.
Purpose of the Study:
- To generate a novel mouse-adapted (MA) EBOV model based on the 2014 Makona isolate.
- To characterize the virulence and pathogenesis of the new MA-EBOV in immunocompetent adult mice.
- To identify genetic determinants of virulence in the adapted EBOV strain.
Main Methods:
- Generation of MA-EBOV by incorporating Mayinga-MA mutations into the Makona isolate genome.
- Serial passaging of rescued virus in suckling mice to achieve mouse adaptation.
- Reverse genetics to assess the role of specific mutations (VP24) in virulence.
Main Results:
- The novel EBOV/Makona-MA causes lethal disease in adult immunocompetent mice within 6-9 days (LD50 = 0.004 PFU).
- Infected mice exhibited viremia, high viral loads in organs, elevated pro-inflammatory cytokines, and lymphopenia.
- A mutation in the viral membrane-associated protein VP24 was identified as critical for EBOV/Makona-MA virulence.
Conclusions:
- The developed EBOV/Makona-MA provides a valuable immunocompetent mouse model for studying contemporary EBOV variants.
- This model will accelerate the pre-clinical evaluation of therapeutics and vaccines against EBOV.
- Understanding the role of VP24 in virulence advances knowledge of EBOV pathogenesis.
