At this time, there is no treatment or vaccine for the SARS-CoV-2 coronavirus. However, German researchers recently identified a “sybody” capable of neutralizing the virus in the laboratory. This synthetic mini antibody would show promise in the development of an effective treatment.
A synthetic mini antibody
Since the start of the Covid-19 pandemic, research has been in full swing. Many research units and laboratories are looking for a treatment and / or a vaccine to curb the epidemic. In their work published in the journal Nature Communications on November 4, 2020, researchers at the European Molecular Biology Laboratory (EMBL) in Hamburg (Germany) discussed a potential solution. The study authors mentioned a “sybody”, a small synthetic antibody with the ability to neutralize the coronavirus in the lab.
Remember that SARS-CoV-2 uses the ACE2 receptor in human cells to enter the body. The key to the virus is none other than the Receptor binding domain (RBD) surface protein. In theory, the solution seems rather simple: discover a product that can bind more to RBD than to the ACE2 receptor. Thus, access to the latter would be blocked, as would the infection. Antibodies are therefore currently a promising option in several clinical trials. Produced by white blood cells, their mission is to neutralize the invader.
An ideal candidate
Unfortunately, previous studies of recovering patients believe that not all antibodies are created equal. In addition, producing these neutralizing antibodies as a drug is very expensive and involves a complex process. EMBL researchers then conducted the investigation on the side of “nanobodies”. These are mini antibodies, especially found in dromedaries and llamas. The study authors indicate that other research has already shown that nanobodies can inhibit the binding of RBD to ACE2, and therefore neutralize the virus.
However, the ideal nanobodies remained to be discovered. Generally speaking, nanobodies are isolated from immune camels. On the other hand, today there are libraries of synthetic nanobodies (or sybodies) allowing a faster and more economical selection. However, the researchers say they have found a candidate in one of these databases.
A faster and more economical method
The study directors first tested the ability of each of the sybodies to bind to RBD. Out of 85 sybodies, number 23 (Sb23) showed stability and some efficiency. In all, the researchers tested 36 sybodies and 11 of them were able to neutralize the coronavirus. It was actually a bogus virus, made from a harmless lentivirus associated with RBD. Here again, Sb23 stood out by binding to RBD in a very efficient manner. Moreover, this result is the same, regardless of whether the RBD is in “arm up” or “arm down” mode, modes that allow or not the link.
The process in question took only three weeks. However, the usual method on llamas or dromedaries would have required at least six weeks, and this, only for the stage of immunization of the animals. In all, the process would have taken at least four months. The next step for the researchers will be to verify the effectiveness of Sb23 in humans.
