A new treatment for Covid-19, developed with the help of a llama called Fifi, has shown "significant potential" in early trials. The treatment uses nanobodies, which are small fragments of antibodies, substances carried in the blood that helps destroy microbes and viruses. Llamas and other members of the camel family (along with sharks) produce these nanobodies naturally in response to infection. If the treatment tests successfully in humans, it could be given to people as a simple nasal spray, both to treat and perhaps even prevent infection. Professor James Naismith of the Rosalind Franklin Institute in Oxfordshire, England, who helped lead the research, described nanobodies as "fantastically exciting".

23rd September 2021

What are nanobodies?

Llamas have evolved immune systems to produce nanobodies to counter an infection. Why this occurs in camels and sharks is, as yet, a mystery to science. Llama nanobodies have been shown to be just as effective at targeting antigens as antibodies—and can even work better.

​​​​​​​Just like the antibodies in our bloodstream, nanobodies latch on to antigens, including viruses and bacteria, that invade our bodies. The nanobodies disarm the viruses by blocking them from infecting human cells. They also act as a "tag", alerting the body's immune system to target the antigens for destruction by killer cells.

Nanobodies have other advantages, too. They can be easily grown in large concentrations in the laboratory. Being smaller than antibodies makes them easier to insert into bacterial cells for bulk production, so they are cheaper to mass-produce. They can be self-administered using a nasal spray at home, rather than needing an injection. This way, the treatment is actually delivered more directly to the site of infection—in the airways—rather than via the bloodstream.

The research team was able to obtain the nanobodies by injecting a tiny, non-infectious piece of the coronavirus (a protein from the spikes that surround the virus's body) into a llama called Fifi, who is part of the antibody production unit at the University of Reading. Fifi did not become sick as a result of the injection. Instead, her immune system was triggered to combat the spike protein by making nanobodies against it. The researchers were able to extract these from a blood sample from Fifi. They picked out the ones that matched the viral protein most closely and which would therefore be most capable of binding to the virus. The team then grew large quantities of these specially selected nanobodies in the laboratory.
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Scientists are greatly encouraged by the possibilities of the new treatment, although its effectiveness and safety need to be fully tested before moving to human trials.

Even with the success of the Covid vaccines, having effective treatments in the future will still be important to counter the possible emergence of new variants that are capable of bypassing vaccine immunity. Also, not everyone responds to vaccination, and immunity can fade in individuals at different times. With much of the developing world lagging behind in the bid to vaccinate everyone against Covid-19, having a cheap and effective treatment could be crucial in tackling the disease in the coming years.
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