Researchers at Weill Cornell Medicine – Qatar (WCM-Q) believe camels could be a source of therapeutic antibodies – and potentially a cure – for humans with COVID-19.
Although there are a number of vaccines now available for COVID-19, humanity is still in need of an effective cure for the disease and for possible future pandemics which could be caused by yet unknown coronaviruses.
WCM-Q professor Dr Lotfi Chouchane believes that dromedary camels may offer a solution to the problem. This is because the camel’s single-chain antibodies (nanobodies) could be produced in large quantities and access viral targets that are hidden for conventional antibodies.
Family of coronaviruses
There have been three major outbreaks of coronaviruses so far: SARS in 2002, MERS in 2012 and the current COVID-19.
The viruses all belong to the same sub-family of coronaviruses and are all believed to have originated in bats before being passed onto an intermediate host and then onto humans. For the MERS virus, the unique intermediary host was the dromedary camel.
Dr Chouchane said that you can find MERS virus antibodies in camels easily but rarely do you find an animal suffering from the disease. It appears, he said, that the dromedary’s immune system is able to rapidly overcome the infection.
Our hypothesis was that given the similarity between the viruses causing MERS and COVID-19, could the MERS virus antibodies produced by camels also be effective against the COVID-19 virus?
With support from WCM-Q, Qatar National Research Fund, the Ministry of Public Health (MoPH) and the Ministry of Environment and Municipality, samples were taken from a biorepository of camel specimens taken before and after the COVID-19 pandemic emerged, of which all animals had antibodies to the MERS virus.
Working with colleagues from WCM-Q, Sidra Medicine and MoPH, Dr Chouchane found that the dromedaries’ MERS virus antibodies were indeed able to prevent the COVID-19 virus from binding to its target cells.
Stopping the virus in its tracks
The next stage was to discover the target of the COVID-19 virus camel antibodies, which was done by sophisticated molecular techniques. This allowed the researchers to understand exactly which section of the viral proteins was responsible for neutralizing antibodies and stopping the virus in its tracks.
Importantly, because SARS, MERS and COVID-19 viruses are all so similar, this common section could be used as therapy for all three, along with potential variants and future coronaviruses belonging to the same sub-family.
The proposed therapy is to come up with engineered camel antibodies formed by three or four small camel antibodies in one molecule, which each recognising different parts of the virus. The infected subject would then be injected with these antibodies and the combination of three or four would increase the chance of success.
While transplants of animal tissue to humans have generally failed due to rejection by the immune system, the researchers do not believe there should be an issue with using antibodies from a different species.
According to Dr Chouchane, they are only using the section of the antibody which targets the virus and if you look at the antibodies produced by dromedaries, they are very similar structurally to those produced by humans.
… So we do not foresee a negative cross-species immunogenic response to the therapy.
Not a replacement for COVID-19 vaccines
Dr Chouchane stressed that the antibody therapy will not be a replacement for the existing vaccines. We hope that the vaccine availability will alleviate the pandemic by introducing herd immunity, he said, but there are hurdles to overcome, such as new variants, although thankfully it looks like some of the COVID-19 vaccines are able to recognise these.
The main goal of vaccines, however, is to interrupt the spread of the virus, but not to treat the patient. At the end of the day, there will still be patients who will develop the disease, and the dromedary antibodies could be a therapeutic tool.
The next task for the researchers, which could take as little as a few months, is for the hypothesis to be proved safe and effective in rodents. If successful, it would go onto the next stage of development, and would probably be undertaken by a multinational pharmaceutical company.
The complete research paper, ‘Dromedary camels as a natural source of neutralizing nanobodies against SARS-CoV-2’, has recently been published in JCI Insight, a prominent journal of the American Association of Clinical Investigation. Read it here.
For more information about WCM-Q, visit qatar-weill.cornell.edu.
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