Most of the efforts to fight coronavirus have focused on public health measures and the race to develop vaccines. However, a team from Columbia University, Cornell University and others have developed something new: a nasal spray can directly attack the virus. In a new published study, the mixture was effective in neutralizing the new coronavirus before it could infect cells.
Like all viruses, SARS-CoV-2 (the causative agent COVID-19) needs to enter cells to reproduce. The virus injects its RNA genome and takes control of cell machinery to make copies of itself, eventually killing the cell and spreading new viral particles to infect other cells. To gain access to a cell requires a “key” that matches the protein lock on the cell surface. In the case of SARS-CoV-2, we call it the spike protein, and that’s where the new nasal spray blocker hits.
Protein spikes “decompress” when it meets a cell, exposing two amino acid chains (the building blocks of proteins). The spray contains lipoprotein, which has an additional chain of amino acids linked to a cholesterol particle. Lipoprotein inserts itself into the mutant protein, sticking to one of the chains that otherwise binds to the receptor and allows the virus to infect the cell. With that lipoprotein, the virus is inactivated.
This work is still in its early days, and there are no human trials yet. The study was based on experimentation with a small number of ferrets, some being sprayed with real lipoproteins and some given a placebo. The animals were used because they were susceptible to a variety of human respiratory infections that were subsequently intentionally exposed to coronavirus. The animals receiving the drug were not infected with COVID-19, but the controls did.
The study, to date only available on the pre-printed bioRxiv server, showed that lipoprotein spraying completely prevented virus infection in laboratory animals. The team believes the aerosol will stay around the nasal and lung cells for about 24 hours.
It will take a lot of extra work to confirm the mixture is safe before any human testing can begin, but this could be worth it. Unlike similar attempts to prevent SARS-CoV-2 from relying on antibodies and other complex proteins, lipoproteins do not have any special storage requirements. It can be transported in dry powder form and stored at room temperature. This could make it ideal for slowing the spread of COVID-19 in poor countries with limited access to medical care.
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