Most efforts to combat the coronavirus have focused on public health measures and the race to develop a vaccine. However, a team from Columbia University, Cornell University, and others has developed something new: a nasal spray that attacks the virus directly. In a newly released study, the concoction was effective at deactivating the novel coronavirus before it could infect cells.
Like all viruses, SARS-CoV-2 (the causative agent of COVID-19) needs to enter a cell to reproduce. The virus injects its RNA genome and hijacks cellular machinery to make copies of itself, eventually killing the cell and spreading new virus particles to infect other cells. Gaining access to a cell requires a “key” that fits into a protein lock on the cell surface. In the case of SARS-CoV-2, we call that the spike protein, and that’s where the new nasal spray blocker attacks.
The spike protein “unzips” when it meets up with a cell, exposing two chains of amino acids (the building blocks of proteins). The spray contains a lipoprotein, which has a complementary strand of amino acids linked with a cholesterol particle. The lipoprotein inserts itself into the spike protein, sticking to one of the chains that would otherwise bind to a receptor and allow the virus to infect the cell. With that lipoprotein in the way, the virus is inactivated.
This work is still in the very early days, and there have been no human trials. The study is based on testing with a handful of ferrets, several of which received the real lipoprotein spray and several who were given a placebo. The animals, which were used because they are susceptible to many human respiratory infections, were then deliberately exposed to the coronavirus. The medicated animals didn’t contract COVID-19, but the controls did.
The study, which is so far only available on the preprint bioRxiv server, shows that the lipoprotein spray completely stopped viral infection in the experimental animals. The team believes the spray will linger around the cells of the nose and lungs for approximately 24 hours.
It will take additional work to confirm the mixture is safe before any human trials can begin, but this could be worth the time. Unlike similar attempts to block SARS-CoV-2 that rely on antibodies and other complex proteins, a lipoprotein doesn’t have any special storage requirements. It can be shipped in dry powdered 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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