The pandemic virus SARS-CoV-2 continues to cause infections as it mutates into new variants. While the vaccines that are available have been able to significantly reduce the likelihood that vaccinated people will be hospitalized or die from the virus, they have not been exceptionally good at preventing infection. The mRNA vaccines are also based on the spike protein, which has kept evolving as new variants have emerged, and protection is waning.
Researchers have been trying to develop a great vaccine for SARS-CoV-2 since the COVID-19 pandemic began, but traditional vaccines can take years to perfect, produce, and test. We were lucky to have access to mRNA technology that brought us vaccines quickly, but there is a lot of room for improvement.
New research reported in Science Translational Medicine has described a different approach to a SARS-CoV-2 vaccine that has taken inspiration from evolution of the virus. In this study, the investigators assessed he sequences of 11,650,487 SARS-CoV-2 samples. This revealed that the spike protein of the virus, which is used by the pathogen to latch onto and infect cells, has not experienced a random evolutionary trajectory. Instead, the virus has followed paths of either high infectivity with low immune resistance or low infectivity with high immune resistance.
The infectivity and immune resistance of SARS-CoV-2 variants tend to be incompatible, the researchers found, with the exception of the Beta and Kappa variants. Omicron exhibited the highest degree of immune resistance when it was tested in cell lines, and demonstrated high infectivity in one type of cell.
The researchers used this data to design a vaccine antigen called Span, which is aimed at multiple targets on the virus. The Span protein carries sequences that are consistently found in many viral variants throughout the evolution of the virus, so the vaccine should provide protection against many existing and emerging variants of SARS-CoV-2.
When tested in an animal model, the Span vaccine triggered the production of antibodies that could neutralize different variants of the SARS-CoV-2 virus, and was totally effective against mortality caused by Omicron. This study has highlighted how different vaccine designs can help keep people protected as the SARS-CoV-2 virus continues to evolve and cause new infections. This vaccine stil has to be tested in people, however.
Other teams of researchers are also working to develop different kinds of SARS-CoV-2 vaccines.
Source: Science Translational Medicine
