The protection conferred by current single-antigen expressing COVID-19 vaccines is known to be declining over time. Our approach, which is to combine the expression of Spike and Nucleoprotein into one single vector, aims at triggering a better induction of the cellular arm of immunity, thus extending the duration of the protection conferred by the vaccine. Induction of a strong cellular immunity is also needed to better address the emergence of new SARS-CoV-2 variants.
Pre-existing immunity against the vector is a common issue with vector-based vaccine candidates. Due to the low prevalence and short-lived pre-existing anti-ORFV immunity in humans, Prime-2-CoV-based vaccines are expected to support repeated vaccinations.
The Prime-2-CoV vaccine platform was established at the University of Tübingen, Germany. It is based on a highly attenuated and non-pathogenic live viral vector D1701-VrV derived from an ORF Virus isolate, naturally infecting sheep and cattle. Used for 20 years in biomedical research and veterinary medicine, this vector has highly beneficial characteristics for the development of a COVID-19 vaccine:
Most of existing COVID-19 vaccines only target a single antigen, the Spike protein of the SARS-CoV-2 virus. Speransa’s multivalent vaccine approach allows for immunization with additional target antigens. In addition to the Spike protein, our second-generation vaccine candidate Prime-2-CoV also expresses the nucleocapsid protein N of SARS-CoV-2, for a broadened immune response against infection, long-lasting immunity and increased protection against new variants.
Current technologies require challenging cold supply chain logistics preventing a wide, global vaccine distribution. Speransa’s Prime-2-CoV vector platform demonstrates a high thermal stability, even after several weeks of ambient temperature storage.