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Most efforts to fight 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 have developed something new: a nasal spray that directly attacks the virus. In a recently published study, the concoction was effective in deactivating the new coronavirus before it could infect cells.
Like all viruses, SARS-CoV-2 (the causative agent of COVID-19) must enter a cell to reproduce. The virus injects its RNA genome and hijacks the cellular machinery to make copies of itself, ultimately killing the cell and shedding new viral particles to infect other cells. To access a cell, you need a “key” that fits into a protein lock on the cell’s surface. In the case of SARS-CoV-2, we call this the spike protein, and this is where the new nasal spray blocker attacks.
The spike protein “decompresses” when it encounters 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 bound to a cholesterol particle. The lipoprotein fits 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 this lipoprotein on the way, the virus is inactivated.
This work is still in its very early stages and there has been no human testing. The study is based on tests with a handful of ferrets, several of which received the real lipoprotein spray and several that received a placebo. The animals, which were used because they were susceptible to many human respiratory infections, were then deliberately exposed to the coronavirus. The medicated animals did not contract COVID-19, but witnesses did.
The SARS-CoV-2 spike protein. Credit: NIH
The study, which has so far only been available on the bioRxiv preprint server, shows that the lipoprotein spray completely stopped the viral infection in laboratory animals. The team believe the spray will persist around cells in the nose and lungs for about 24 hours.
It will take additional work to confirm the mixture is safe before any human testing can begin, but it could be worth it. Unlike similar attempts to block SARS-CoV-2 which rely on antibodies and other complex proteins, a lipoprotein does not have special storage requirements. It can be shipped as a dry powder 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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