Researchers at the Rosalind Franklin Institute in the UK found that nanobodies -- a smaller, simple form of antibody -- can effectively target the SARS-CoV-2 virus.
The study, published in the journal Nature Communications, shows that short chains of the molecules, which can be produced in large quantities in the laboratory, significantly reduced signs of the COVID-19 disease when administered to infected animal models.
The nanobodies, which bind tightly to the SARS-CoV-2 virus, neutralizing it in cell culture, could provide a cheaper and easier to use alternative to human antibodies taken from patients who have recovered from COVID-19, the researchers said.
Human antibodies have been a key treatment for serious COVID-19 cases during the pandemic, but typically need to be administered by infusion through a needle in the hospital, they said.
"Nanobodies have a number of advantages over human antibodies," said Professor Ray Owens, from Rosalind Franklin Institute and lead author of the research.
"They are cheaper to produce and can be delivered directly to the airways through a nebulizer or nasal spray, so can be self-administered at home rather than needing an injection," Owens said.
This could have benefits in terms of ease of use by patients but it also gets the treatment directly to the site of infection in the respiratory tract.
The team was able to generate the nanobodies by injecting a portion of the SARS-CoV-2 spike protein into a llama called Fifi, which is part of the antibody production facility at the University of Reading in the UK.
The spike protein is found on the outside of the virus and is responsible for binding to human cells so it can infect them.
Although the injections did not make Fifi sick, it triggered her immune system to fight off the virus protein by generating nanobodies against it.
A small blood sample was then taken from the llama and the researchers were able to purify four nanobodies capable of binding to the SARS-CoV-2 virus.
