Jahnavi Sarma
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Written By: Jahnavi Sarma | Updated : September 5, 2020 5:30 PM IST
The search for effective nanobodies, which are fragments of antibodies that occur naturally in camelids and can be adapted for humans, began in February when an alpaca (animal) was injected with the new coronavirus' spike protein, which is used to enter our cells.
Since the beginning of the pandemic, scientists have been trying to develop an effective treatment to fight the COVID-19 virus. Today, many hopeful vaccine candidates are in the final stages of development and experts hope to have them in the market in the near future. But, till date, scientists have not been able to develop any effective treatment against the viral disease. But now, there is a ray of hope in the form of nanobodies.
To fight against the COVID-19 pandemic, scientists have identified a small neutralising antibody, a so-called nanobody, that has the capacity to block SARS-CoV-2 from entering human cells. The study, published in the journal Nature Communications, suggests that this nanobody has the potential to be developed as an antiviral treatment against COVID-19. Researchers from the Karolinska Institute in Sweden are hopeful that this finding can contribute to the amelioration of the COVID -19 pandemic by encouraging further examination of this nanobody as a therapeutic candidate against this viral infection.
The search for effective nanobodies, which are fragments of antibodies that occur naturally in camelids and can be adapted for humans, began in February when an alpaca (animal) was injected with the new coronavirus' spike protein, which is used to enter our cells. After 60 days, blood samples from the alpaca showed a strong immune response against the spike protein. Next, the researchers cloned, enriched and analysed nanobody sequences from the alpaca's B cells, a type of white blood cell, to determine which nanobodies were best suited for further evaluation. They identified one, Ty1 (named after the alpaca Tyson), that efficiently neutralizes the virus by attaching itself to the part of the spike protein that binds to the receptor ACE2, which is used by SARS-CoV-2 to infect cells. This blocks the virus from slipping into the cells and thus prevents infection.
Using cryo-electron microscopy, researchers were able to see how the nanobody binds to the viral spike at an epitope which overlaps with the cellular receptor ACE2-binding site, providing a structural understanding for the potent neutralisation activity. According to the researchers, nanobodies offer several advantages over conventional antibodies as candidates for specific therapies. They span less than one-tenth the size of conventional antibodies and are typically easier to produce cost-effectively at scale. Critically, they can be adapted for humans with current protocols and have a proven record of inhibiting viral respiratory infections. The results of this study show that Ty1 can bind potently to the SARS-CoV-2 spike protein and neutralize the virus, with no detectable off-target activity. Researchers are now embarking on preclinical animal studies to investigate the neutralizing activity and therapeutic potential of Ty1 in vivo.
(With inputs from IANS)
