Researchers discover special antibodies in monkeys that are said to be effective against all variants of Sars-CoV-2. It is another spectacular find of this kind that gives hope for a victory against the mutating virus. Is this justified? There are doubts.
The Sars-CoV-2 coronavirus is always one step ahead of vaccine developers due to its eagerness to mutate. A way out of this dilemma could lie in antibodies that are equally effective against all variants of the virus, both current and future. Now a research team from the Scripps Research Institute in California is reporting on a candidate that gives hope in this regard.
In experiments with rhesus monkeys, the researchers from California discovered amazing antibodies that are effective against many different Sars-CoV-2 variants - and even against less closely related corona viruses such as Sars-CoV, which caused a smaller pandemic in 2002/2003. According to the researchers, these "Pan-Sars virus" antibodies could help in the production of better vaccines. Their study has now been published in the journal Science Translational Medicine.
The scientists had administered the Sars-CoV-2 spike protein to rhesus monkeys. The spike protein is the prominent spikes on the virus' coat that it uses to gain access to host cells. However, the immune system of the monkeys reacted differently than that of humans: It produced a wider range of antibodies - including those that were effective against other variants.
Upon closer inspection of the antibodies, the researchers realized why. Human antibodies usually attack that part of the spike protein of the virus that docks onto the cells. However, this area changes from variant to variant, so that antibodies once formed lose their effectiveness. In the monkeys, the scientists discovered numerous antibodies that target a different part of the spike protein that changes less frequently. Another group of US researchers reported a similar discovery at the end of July.
"The antibody structures reveal an important area that is common to several Sars viruses," said Ian Wilson, one of the authors of the study. "This site has rarely been targeted by human antibodies before." New strategies are now conceivable to train the immune system to recognize this vulnerable part of the virus.
The authors express hope that their discovery could help develop next-generation vaccines. "If we can develop vaccines that elicit broad-based responses similar to those we saw in this study, these treatments could allow broader protection against the virus and the variants in question," said lead author Raiees Andrabi. However, the authors emphasized that further research is needed first.
At the end of July, a team led by researchers from the University of Alabama reported the discovery of antibodies that also act against different variants of Sars-CoV-2 and even more distantly related cold coronaviruses. They also attack a spot on the spike protein that has so far been spared from mutations: its stalk.
The US company Aridis is already working on a drug made from these universal antibodies. And reports of successes: In animal experiments, no Sars-CoV-2 viruses were detectable in infected rhesus monkeys after treatment with such an antibody cocktail, according to a recent company announcement. Experiments in the test tube would also indicate that the agent is also effective against different omicron variants.
The German virologist Klaus Stöhr had recently expressed little optimism about the supposed miracle antibodies. "Unfortunately, the 'universal' antibodies will not be a solution for the vaccines of the near future," Stöhr wrote on Twitter. With new antibodies, "selection pressure for this part of the spike protein would also arise and thus variants that would make it necessary to adapt the vaccine again".
