Nasal Antiviral Spray That Blocks Transmission of SARS-CoV-2 in Ferrets Could Halt Spread of COVID-19

The researchers had previously created similar lipopeptides - small proteins joined to a cholesterol or tocopherol molecule - to prevent infection of cells by other viruses, including measles, parainfluenza, and Nipah viruses. The lipopeptides work by preventing a virus from fusing with its host’s cell membrane, a necessary step that enveloped viruses, including SARS-CoV-2, use to infect cells. To fuse, the new coronavirus unfolds its spike protein before contracting into a compact bundle that drives the fusion. The compound designed by the researchers recognizes the SARS-CoV-2 spike, wedges itself into the unfolded region, and prevents the spike protein from adopting the compact shape necessary for fusion.

In the ferret experiments, the lipopeptide was delivered into the noses of six ferrets. Pairs of treated ferrets were then housed with two control ferrets that received a saline nasal spray and one ferret infected with SARS-CoV-2. After 24 hours of intense direct contact among the ferrets, tests revealed that none of the treated ferrets caught the virus from their infected cagemate and their viral load was precisely zero, while all of the control animals were highly infected.

The new nasal lipopeptide could be ideal for halting the spread of COVID-19. The antiviral lipopeptide is inexpensive to produce, has a long shelf life, and does not require refrigeration. These features make it stand out from other antiviral approaches under development, including monoclonal antibodies. The transportable and stable compound could be especially key in rural, low-income, and hard-to-reach populations. The researchers have proposed that these peptides could be used in any situation where an uninfected person would be exposed, whether in a household, school, health care setting, or community. The antiviral is easily administered and, based on the scientists’ experience with other respiratory viruses, protection would be immediate and last for at least 24 hours. The scientists hope to rapidly advance the preventative approach to human trials with the goal of containing transmission during this pandemic. People who cannot be vaccinated or do not develop immunity will particularly benefit from the spray.

“Even in an ideal scenario with large segments of the population vaccinated - and with full trust in and compliance with vaccination procedures - these antivirals will form an important complement to protect individuals and control transmission,” said the researchers.

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