Antibodies are an integral component of the human immune system, they are infection-fighting proteins, that have specificity and strong affinity of attachment to their respective proteins. The same theory is applied in antibody-based treatment, where antibodies are enabled to bind to diseased proteins. Nanobodies are unique antibodies (small immune proteins) that are produced naturally by alpacas as a response to infection.
Scientists in Australia have spotted neutralizing nanobodies that have an affinity to inhibit SARS-CoV-2 from penetrating the cells in pre-clinical models, thus paving way for the future of Nano-body-based treatment of COVID-19. The study was published in PNAS, led by Australia’s expert academic leaders in infectious diseases and antibody therapy at WEHI.
The synthetic spike protein in alpacas, cannot cause infection or disease, but it lets alpacas develop nanobodies. The gene sequence of those nanobodies can be encoded and further allows scientists to develop millions of types of nanobodies in the lab and then selecting the best spike-bindingprotein. The selected nanobodies were combined in a ‘nanobody cocktail’ to test their efficacy in blocking the entry of SARS-CoV-2 into the cell and reducing viral loads, in pre-clinical models.
The scientists used Cryo-Electron Microscopy (EM) to directly image and map the neutralizing interaction of nanobodies with the spike protein at near-atomic resolution. Same Cryo-EM has been used as a drug discovery tool during the COVID-19 pandemic. During the mapping process, the researchers were able to recognize a nanobody that identified the SARS-CoV-2 (both original SARS-CoV and emerging global variants). Scientists are hopeful that this Nano protein can provide cross-protection against both the coronavirus variants.
SARS-CoV-2, COVID-19, nanobody, Nano-protein, Cryo-Electron Microscope.