A visualization of the immune engineering process, from structure selection to authentic virus neutralization. (Credit: UCSD)

A different way to build a COVID-19 vaccine is said to remain effective against new and emerging variants and could be taken as a pill, by inhalation, or other delivery methods.

The research involved building plasmids genetically altered to contain bits of genetic material specifically intended to target a vulnerability in the SARS-CoV-2 virus’s spike protein, a portion of the virus critical to binding and infecting cells. Plasmids can be used to transfer genetic material from one cell to another, after which the introduced genetic material can replicate in the receiving cell.

The researchers built plasmids containing immunogens — molecules that cause B lymphocytes to create antibodies — that were specifically designed to display a knob of the spike protein that is part of the receptor binding motif or RBM. They cloned the selected spike protein amino acids into a plasmid DNA so that, when injected into the spleen of mice, the introduced immunogen molecules would provoke the production of neutralizing antibodies specifically tuned to the targeted nob on the RBM of the virus protein spike.

They tested their approach on mice with variants of the original SARS-CoV-2 strain (beta, delta, and omicron) and found that the immune response was similar across all variants.