Nanobodies in Alpaca Can Neutralize SARS-CoV-2 and Its Variants, Hold Potential for Novel Treatments Against COVID-19

The need for effective therapeutics against severe COVID-19 remains high despite the continuous efforts of vaccinating people. One of the promising candidates is the nanobodies, which are fragments of antibodies found in camelids and adapted for humans.

These miniature antibodies offer several advantages over the conventional one, having favorable biochemical properties that can neutralize SARS-CoV-2 and its variants. In the now published studies, scientists wrote that they were able to identify several potent nanobodies from alpaca, which could pave the way for new treatments against COVID-19.

(Photo : Pixabay/sharonang)
Nanobodies in Alpaca Can Neutralize SARS-CoV-2 and Its Variants, Hold Potential for Novel Treatments Against COVID-19

How Do Nanobodies Work?

Nanobodies are small fragments of antibodies that bind to a specific domain of an antigen to immobilize the virus using the small structure that allows them to get into folds and crannies in viral spike proteins, according to Earth.com. These miniature antibodies are produced in the members of the camel family, such as alpacas and camels, as a reaction to the SARS-CoV-2 virus.

Moreover, their small size has given them advantages over other therapies. An article in Sweden's COVID-19 Data Portal reported that these nanobodies are simple to clone and express, stable, have high specificity and affinity in binding to spike protein, and are highly scalable as they can be mass-produced and cost-effective.

Additionally, nanobodies can be combined to form homodimers, heterodimers, or multimers that increase their potency to simultaneously target multiple epitopes. It offers the ideal treatment without the risk of being rendered less likely effective because of viral escape.

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Scientists Found A Way to Identify Nanobodies in Alpaca

The team published two studies that describe how they generated a nanobody with two non-overlapping interaction sites. In the first study, titled "A Bispecific Monomeric Nanobody Induces Spike Trimer Dimers and Neutralizes Sars-CoV-2 in Vivo," published in Nature Communications, the team describes a single nanobody called Fu2, which is named after the alpaca Funny.

As EurekAlert! reported, Fu2 nanobody significantly reduced viral load in cell cultures of mice by naturally binding to two sites of the viral spike, causing SARS-CoV-2 to lose its ability to attach itself to the host's ACE2 receptors.

Then they delved deeper into the alpaca's nanobodies by combining it with a range of advanced laboratory techniques that resulted in a library of nanobodies they described in their second study, titled "Multivariate Mining of an Alpaca Immune Repertoire Identifies Potent Cross-Neutralizing Sars-CoV-2 Nanobodies," which was published in Science Advances.

The findings revealed that additional nanobodies effectively cross-neutralized SARS-CoV-2, its beta variant, and more distantly related SARS-CoV-1.

Researchers noted that these nanobodies pave the way for therapeutic candidates against SARS-Cov-2, the virus that causes COVID-19, and its variants. Now, they are applying similar techniques to identify which nanobodies can best deal with the Omicron variant. These libraries of nanobodies hold potential for future antiviral development.