WEHI researchers are studying ‘nanobodies’ – tiny immune proteins made by alpacas—in a bid to understand whether they might be effective in blocking SARS-CoV-2, the virus that causes COVID-19.

Alpacas produce unique antibodies—called nanobodies—that can bind very specifically to a protein. The research team are developing nanobodies specific for the SARS-CoV-2 ‘spike’ protein, which sticks out from the surface of the virus and allows the virus to bind and enter human cells.

The team hopes that developing nanobodies against the ‘spike’ protein could be an important step towards new antibody-based ‘biologics’ therapies to treat COVID-19.

This nanobody program against COVID-19 is part of a consortium-led effort that brings together the expertise of Victorian and Australian academic and industry leaders in infectious diseases and antibody therapeutics at WEHI, the Doherty Institute, CSL, Affinity Bio, CSIRO, the Burnet Institute and the Kirby Institute.

Antibodies are key infection-fighting proteins in our immune system. An important aspect of antibodies is that they bind tightly and specifically to another protein, said Associate Professor Wai-Hong Tham, who is leading the research at WEHI.

“Antibody-based therapies—or ‘biologics’—utilize this property of antibodies, harnessing an antibody that binds specifically to a protein involved in disease. In our case, we are looking to develop a therapy that binds to the SARS-CoV-2 virus’ ‘spike’ protein, which it uses to get into human cells. These antibodies could prevent the virus binding to the human receptor called ACE2—stopping the COVID-19 infection cycle,” she said.

A quirk of the alpaca immune system makes alpaca antibodies a key resource in this project.

“Alpacas make unique antibodies, which are smaller than conventional antibodies. Conventional antibodies are composed of two immunoglobin—heavy chains and light chains—whereas alpacas make the majority of antibodies that lack the light chains. Nanobodies are laboratory-made antibody fragments of the heavy chain only domain that recognizes foreign proteins. These bind really specifically to their target protein and are more stable than other antibodies,” Associate Professor Tham said.

Top Image Credit:   phys.org

Post by Amanda Scott, NA CEO.  Follow her on twitter @tantriclens

Thanks to Heinz V. Hoenen.  Follow him on twitter: @HeinzVHoenen