Complete substitution with modified nucleotides in self-amplifying RNA suppresses the interferon response and...

Area of Science:

• Molecular Biology
• Immunology
• Vaccine Development

Background:

• Self-amplifying RNA (saRNA) therapeutics aim for sustained protein expression but face challenges with interferon response.
• Previous attempts to modify nucleotides in saRNA for immune evasion and enhanced translation have been unsuccessful.

Purpose of the Study:

• To identify modified nucleotides that enable 100% substitution in saRNA.
• To achieve innate immune evasion and robust, long-term protein expression from saRNA.
• To develop a saRNA vaccine formulation for protection against SARS-CoV-2.

Main Methods:

• Systematic substitution of nucleotides in saRNA with modified versions.
• In vitro assessment of interferon response and protein expression.
• Formulation of saRNA into a vaccine for in vivo studies.
• Challenge studies in mice with SARS-CoV-2.

Main Results:

• Identified specific modified nucleotides conferring innate immune evasion when substituted at 100% in saRNA.
• Demonstrated robust, long-term protein expression from modified saRNA.
• Developed a saRNA vaccine formulation that protected mice against lethal SARS-CoV-2 challenge.

Conclusions:

• This study successfully identified modified nucleotides for saRNA, overcoming previous limitations in immune suppression and translation.
• The developed saRNA technology enables prolonged protein expression at low doses, advancing saRNA therapeutics.
• The findings support the potential of saRNA as a platform for effective vaccines against viral threats like SARS-CoV-2.