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| SARS-CoV-2 is part of the coronavirus family, named for the spikes that stud the surface of the virus and impart a crown-like appearance when viewed through an electron microscope. Image by NIH |
A team of researchers at the University of California San Francisco (UCSF) is claiming to have developed the most potent anti-SARS-CoV-2 antivirals yet discovered. The molecule can be delivered as an aerosol, which the team have dubbed 'AeroNabs', or as a dry powder and could be more effective if used daily than the PPEs used by medical staff and carers.
They developed it from molecules called nanobodies - very small antibody-like particles found in llamas, camels and related animals but not humans. The molecules can be produced in bulk by introducing the genes to make it into yeast or a bacterium such as E. coli and growing them in cultures so they become factories to make the molecules, in the same way insulin is produced in commercial quantities.
The molecule acts as a straight-jacket or sheath over the spike proteins on the surface of the SARS-CoV-2 virus, making it impossible for it to bind to the receptors, ACE2, on the surface of cells of the respiratory tracts. This binding is the initial stage of infection and enables the virus to prise open the cell to inject its RNA package into the cell. Each of the virus' 25 spike proteins has three binding sites, or "receptor binding domains" (RBDs)
The first stage was to scan a recently compiled library of over 1 billion nanobodies using increasingly stringent criteria to weed out weak or ineffective candidates. They narrowed this down to 21 candidates that were able to prevent a modified spike protein from binding to ACE2 receptors.
The three most potent were then tested on live SARS-CoV-2 viruses by Veronica Rezelj, PhD, a virologist in the lab of Marco Vignuzzi, PhD, at Institut Pasteur in Paris. She found that they were extremely potent at preventing infection even at low doses. Not only did they prevent the virus binding to ACE2 but they also held the spike proteins in a 'closed' inactive form, adding an additional layer of protection.
The next step was to repeatedly 'mutate' the nanobodies by systematically replacing every amino acid in its protein, then testing them for their ability to bind to a virus RBD. They narrowed this down to two changes that gave a 500-fold increase in potency.
The third trick was to engineer a molecular chain that bound the nanobodies in groups of three. As noted above, each spike has three RBDs, so if any one nanobody in the chain binds to one RBD the other two will bind to the other RBDs. This gave an increase in potency that was 200,000 times higher. When they linked the mutated nanobodies in these triples the result was 'off the scale'.
Further tests have shown that the molecules are stable at high temperatures and in a dry powder form with a long shelf-life, which means they could be sold 'over the counter' and administered easily via a nasal spray or an inhaler.
AeroNabs are not a cure for Covid-19 but it could be used to protect vulnerable people and carers or the general public pending the development of an effective vaccine.
I hardly need point out how this effort by science contrasts so markedly with the response of religions, which has as often as not seemed more designed to ensure as wide a spread of the virus as possible by refusing to close churches and places of worship, by preaching against lockdown and social distancing and even against wearing facemasks, turning places of worship into infection hot-spots and ensuring that the virus has killed believers disproportionately to non-believers.
The similarity of the research process to a process of evolution by natural selection hardly needs pointing out either.
Is science beginning to turn the tide against creationism's malevolent designer who allegedly intelligently [sic] designed this virus?
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