SARS-CoV-2 spike protein (expressed by Murine Pneumonia Virus vector) (SARS-CoV-2 S (MPV/S-2P))

The SARS-CoV-2 spike protein expressed by the MPV/S-2P vector is a prefusion-stabilized version of the viral surface glycoprotein, designed to elicit robust mucosal and systemic immune responses. The S-2P modification involves two proline substitutions (K986P and V987P) that lock the protein in its prefusion state, which is the most immunogenic form for inducing neutralizing antibodies (Kaiser et al., iScience, 2023). This specific construct is delivered via a live-attenuated Murine Pneumonia Virus (MPV) vector, which has a natural tropism for the respiratory tract but does not cause disease in humans (NIH/NIAID, 2024). By targeting the respiratory mucosa, the vaccine aims to provide superior protection against infection and transmission compared to traditional parenteral vaccines. Preclinical studies in non-human primates have demonstrated high levels of nasal IgA and serum IgG, as well as tissue-resident memory T-cells in the airways (Kaiser et al., Nat Commun, 2024). The vaccine is currently being evaluated in Phase 1 clinical trials as a next-generation booster to enhance immunity in previously vaccinated individuals (NCT06441968).

Other names

SARS-CoV-2 S-2PPrefusion-stabilized SARS-CoV-2 spike proteinMPV-vectored spike proteinMurine pneumonia virus-expressed spike proteinMPV/S-2P vaccine antigen

The MPV/S-2P vaccine functions by delivering a live-attenuated murine pneumonia virus vector that expresses the SARS-CoV-2 spike protein stabilized in its prefusion conformation (S-2P) directly to the respiratory epithelium. This localized expression induces a potent mucosal immune response, characterized by the production of secretory IgA and the recruitment of tissue-resident memory T-cells, alongside a systemic IgG response (Kaiser et al., Nat Commun, 2024). These immune components work together to neutralize the virus at the site of entry, potentially blocking both infection and transmission (NIH/NIAID, 2024).