Terminology
What is an RBD?
The Receptor Binding Domain on the coronavirus spike protein, where the virus attaches to ACE2 receptors on host cells
What was the main hypothesis tested in this study?
Mosaic RBD nanoparticles induce broader and stronger immune responses than homotypic SARS-2 vaccines.
Which vaccine group showed the highest survival rate after SARS-1 challenge?
Mosaic-8b vaccinated mice
What does homotypic mean?
A nanoparticle displaying RBDs from only one virus strain (e.g., SARS-2 Beta)
How was the SpyTag-SpyCatcher system used to build mosaic nanoparticles?
The SpyTag-SpyCatcher system covalently attached RBDs to a 60-mer mi3 protein scaffold to form the mosaic nanoparticle
Which group of mice showed the least weight loss, indicating stronger protection?
The mosaic vaccinated mice (Mosaic-8b and Mosaic-8gm groups)
What is a sarbecovirus?
A subgroup of betacoronaviruses that includes SARS-CoV-1, SARS-CoV-2, and related bat viruses
What test measured how strongly antibodies bind to RBDs?
Elisa (enzyme-linked immunosorbent assay)
In non-human primates, how many immunizations were given before viral challenge?
Monkeys received three doses (prime + two boosts) before being challenged
What is a nanoparticle vaccine?
A vaccine platform that uses a protein scaffold to present viral antigens in a repetitive, ordered structure to the immune system
What method tested virus blocking ability?
Pseudovirus neutralization assay
What did Figures 4B/C show about antibody breadth against SARS-2 and other sarbecoviruses?
Mosaic-8b induced high antibody titers and strong neutralization across both SARS-2 variants and distant sarbecoviruses.
What are mosaic nanoparticles, and why are they important?
Nanoparticles displaying RBDs from multiple sarbecoviruses; they trigger broad cross-reactive immunity and may protect against future coronavirus spillovers
What makes the Authentic Virus Neutralization test different from ELISA or pseudovirus assays?
It uses live virus instead of viral proteins or pseudoviruses, showing real-world antibody protection.
What was the overall conclusion of the paper?
Mosaic RBD nanoparticles elicit broad, cross-protective antibody responses across diverse sarbecoviruses in animal models, supporting their potential as universal coronavirus vaccines