Nanobodies From Alpacas May Protect Against SARS-CoV-2, Study Finds

The researchers discovered multiple antibodies which in cell cultures and mice effectively blocked infection with different SARS-CoV-2 variants, paving the way for new treatments against Covid-19. 

Alpacas (left) (Credit: Getty Images); Fu2 nanobody (pink) bound to the viral spike (right) (Credit: Karolinska Institutet)

New Delhi: A team of researchers have recently developed a novel strategy for identifying potent miniature antibodies, called nanobodies, against emerging SARS-CoV-2 variants, and this approach led to the discovery of multiple antibodies. 

The findings, made by researchers at Karolinska Institutet in Sweden, were recently published in the journals Nature Communications and Science Advances.

The researchers discovered multiple antibodies which in cell cultures and mice effectively blocked infection with different SARS-CoV-2 variants. The findings could pave the way for new treatments against Covid-19. 

In a statement issued by Karolinska Institutet,  Gerald McInerney, joint senior author of both studies, said that with the help of advanced laboratory techniques, the researchers were able to identify a panel of nanobodies that very effectively neutralised several variants of SARS-CoV-2.

The need for effective therapeutics against severe Covid-19 infection remains high despite the roll-out of vaccines and antivirals. 

What Are Nanobodies?

Nanobodies are fragments of antibodies that occur naturally in camelids and can be adapted for humans. Also, nanobodies are promising therapeutic candidates as they offer several advantages over conventional antibodies. For instance, nanobodies have favourable biochemical properties and are easy to produce cost-effectively at scale. 

The researchers, in the recently published studies, have identified several potent antibodies derived from an alpaca immunised with SARS-CoV-2 antigens. 

A Single Nanobody Reduced Viral Load Of SARS-CoV-2

According to the study published in Nature Communications, a single nanobody, Fu2, significantly reduced the viral load of SARS-CoV-2 in cell cultures and mice. Fu2 has been named after the alpaca Funny. The researchers used electron cryo-microscopy (a structural biological method that is used to determine the 3D structures of biomacromolecules) and found that Fu2 naturally binds to two separate sites on the viral spike. In this way, Fu2 inhibits the virus’ ability to enter the host cell. 

The scientists combined a range of advanced laboratory techniques and computational methods. In this way, they found more about nanobodies in alpacas. The findings published in Science Advances revealed additional nanobodies. 

Nanobodies Represent Promising Therapeutic Candidates Against Several SARS-CoV-2 Variants

These nanobodies effectively cross-neutralised both the founder and beta variant of SARS-CoV-2 in cell structures and mice, the researchers found. 

Quoting Leo Hanke, the first author of both studies, the statement said that these nanobodies represent promising therapeutic candidates against several SARS-CoV-2 variants.

According to the statement, the researchers are now trying to figure out which nanobodies from the set are best able to neutralise the Omicron variant of SARS-CoV-2.

Ben Murrell, also joint senior author of both studies, said that the libraries, once established, can be expanded and mined for nanobodies that neutralise new emerging variants.