Low-Dose Self-Amplifying mRNA COVID-19 Vaccine Drives Strong Protective Immunity in Non-Human Primates Against SARS-CoV-2 Infection
Posted by Adam Awdish on
Innovative Grade US Origin Monkey Rhesus Serum and Innovative Grade US Origin Mouse Balb C Serum from Innovative Research were used in the following study:
Amy R. Rappaport, Sue-Jean Hong, Ciaran D. Scallan, Leonid Gitlin, Arvin Akoopie, Gregory R. Boucher, Milana Egorova, J. Aaron Espinosa, Mario Fidanza, Melissa A. Kachura, Annie Shen, Gloria Sivko, Anne Van Abbema, Robert L. Veres & Karin Jooss
Nature Communications
June 7, 2022
As COVID-19 continues to be a global problem, people that were previously vaccinated or infected are getting infected again. Researchers are focused on examining the efficacy of the current COVID vaccines while looking for ways to improve them in future versions.
The two major types of vaccine being used to immunize against COVID-19 are self-amplifying mRNA (SAM) and adenovirus-based vaccines (ChAdOx1/AZD1222, AstraZeneca; Ad26.COV2.S, Janssen). Both formats were between 88-93% effective in preclinical trials. Due to intracellular replication, SAM vaccines offer the potential benefit of high efficacy at low doses and durable antigen expression.
This study evaluated the immunogenicity of both SAM and ChAd vaccines. Researchers collected serum and examined it at various points following vaccination to measure the total anti-S1 IgG and pseudovirus neutralizing antibodies (nAb), whose presence indicates an immune response to the COVID-19 virus.
Researchers initially found that the ChAd-Spike(V1) vaccination was effective, however, the immune response induced by the SAM-Spike(V1) vaccine was much higher. This novel discovery led the researchers to optimize the spike sequence to improve antigen expression. The immune response induced by the ChAd-Spike(V2) and SAM-Spike(V2) vaccines were similar, and both initiated an increased and prolonged immune response when compared to the ChAd and SAM-Spike(V1) vaccines.
The ChAd and SAM-Spike(V2) sequences were further optimized by generating vectors that expressed prefusion-stabilized spike proteins. The researchers mutated the furin cleavage site of the Spike(V2) sequences and introduced proline (P) substitutions to the S2 domain. The new F2P variants of both vaccines increased nAb titers more than the Spike(V2) versions.
These findings made way for further in vivo studies, where researchers observed prolonged immune responses to COVID-19 for weeks following low-dose ChAd and SAM vaccinations.
Related products available from Innovative Research also include:
Innovative Grade US Origin Monkey Rhesus Complement Serum