As the COVID-19 pandemic continues across the world, scientists continue to look at ways to not only improve current vaccines against SARS-CoV-2 – the virus that causes COVID-19 – but to go one step further and create a vaccine that protects against many different types of coronaviruses, including the common cold.
New work has found that a vaccine focused on the S2 portion of the SARS-CoV-2 spike protein is capable of creating antibodies that would not only deal with SARS-CoV-2 but also neutralize other coronaviruses. The design was tested in vitro and in an animal model and the findings are reported in Science Translational Medicine.
“Our goal was to develop new vaccination approaches against SARS-CoV-2 variants and any new variants that may arise in the future," lead author Kevin Ng, a graduate researcher at The Francis Crick Institute, told IFLScience.
"To do this, we made a vaccine based on the S2 region of the spike protein, which is the bit of the protein the virus uses to enter cells. When we vaccinated mice with this S2 vaccine, they generated antibodies that bind and block a wide range of human and animal coronaviruses, including SARS-CoV-2 variants and the common cold coronaviruses.”
Vaccinating mice with SARS-CoV-2 S2 led to the formation of antibodies in those animals that not only dealt with several variants of the COVID-19 virus we have experienced so far, but also with the common cold coronavirus HCoV-OC43, as well as two coronaviruses found in bats. S2 seems to be a very promising target.
“We became interested in the S2 region a few years ago when we discovered that antibodies targeting the common cold coronavirus could also bind SARS-CoV-2,” Ng told IFLScience. “We realised that these cross-reactive antibodies were binding specifically to the S2 region, which is nearly identical in all coronaviruses that infect humans. This type of evolutionary conservation implies that coronaviruses have a hard time mutating this region, and when we in fact look at all of the SARS-CoV-2 variants that have evolved over the past two years, the S2 remains nearly the same.”
S2 is also very similar in many different animal coronaviruses, which means that a vaccine targeting it could prevent animal viruses from effectively jumping to humans. It could be a way to stop future pandemics before they even have a chance to start.
The vaccine would not guarantee that one would never get a cold or COVID again, but that the effects would be much milder, significantly cutting the likelihood of hospitalization and death from the most dangerous members of the coronavirus family.
“It's extremely challenging to design a vaccine that prevents coronavirus infection altogether – this is the reason we get reinfected with the common cold every year,” Ng explained to IFLScience. “Our current vaccines are very good at preventing severe disease and hospitalization, and we hope that our vaccine can be incorporated into existing vaccination regimens or given as a booster in order to train our immune systems to recognize a wider range of coronavirus strains and variants.”
While the result is exciting, the road to such a vaccine being made available in humans is long. But similar approaches are being investigated and a pan-coronavirus vaccine might be closer than we think.
“For now, this work is just a proof of concept in cells and in mice, and the next steps would be to test these vaccines in preclinical animal models that better mimic the history of coronavirus infection and vaccination that we have as humans,” Ng added. “However, there are a number of different pan-coronavirus vaccines in development, including some that have just started human trials.”