SARS-CoV-2, the virus responsible for Covid-19, has been the target of international research teams aiming to find an effective solution against it. A group led by the University of Bonn (Germany) has made a significant breakthrough, identifying and further developing novel antibody fragments, known as nanobodies.
The Discovery of Nanobodies against SARS-CoV-2
In a noteworthy turn of events, the combination of the surface protein of the coronavirus with alpaca and llama led not only to the expected generation of antibodies directed against the virus, but also a simpler antibody variant that could be developed into nanobodies. These nanobodies demonstrate a potential increase in efficiency, attacking different parts of virus simultaneously, which could potentially prevent the pathogen from evading the effect of antibodies through mutations.
Nanobodies’ Novel Mode of Action
Nanobodies appear to instigate a structural change even before the virus encounters its target cell, a newly observed way of action. This modification is thought to be irreversible, effectively preventing the virus from binding to host cells and infecting them.
Antibodies vs Nanobodies
While antibodies are crucial in the immune system’s defense against infections, they can be difficult and time-consuming to produce in large quantities, hence not suitable for widespread use. On the other hand, nanobodies, which are essentially antibody fragments, are simpler and can be produced more economically by bacteria or yeast.
Differences between Nanobodies and Conventional Antibodies
Structurally, conventional antibodies possess two variable domains offering stability and binding specificity, whereas nanobodies have one VHH domain and lack VL domains, making them highly stable. Nanobodies have hydrophilic sides, rendering them soluble without facing aggregation issues unlike conventional antibodies. While the production of nanobodies follows the same protocols as traditional antibodies, they offer distinct advantages such as improved screening, isolation techniques, and no requirement for animal sacrifice.
Benefits of Using Nanobodies
Nanobodies are significantly smaller than classic antibodies, enabling better tissue penetration and easier large-scale production. They are highly stable in varying temperatures, even as high as 80°C and exposure to extreme pH levels, including gastric fluid. Remarkably, if a nanobody unfolds due to high temperatures, this process is fully reversible – something not seen with conventional antibody fragments. Genetic engineering methods can be utilised to improve binding by altering amino acids in nanobodies.
The Drawbacks of Nanobodies
Despite the benefits of nanobodies, there are safety concerns attached to their production. Unlike monoclonal and polyclonal antibodies, the production of nanobodies involves biohazards stemming from the use of bacteriophages for selection, as well as plasmids, antibiotics, and recombinant DNA, requiring safe disposal. Despite these drawbacks, the promising potential of nanobodies in the fight against SARS-CoV-2 cannot be underestimated.