Antitussive spray
Lipopeptide prevents coronavirus transmission among ferrets
Irina Konova, PCR.news
Scientists from the Netherlands and the USA have developed a dimeric lipopeptide that blocks the fusion of SARS-CoV-2 membranes and host cells, and tested it on ferrets. Intranasal administration of lipopeptide has been shown to prevent the transmission of coronavirus between animals. In animals that received lipopeptide intranasally as a preventive measure, a productive infection did not develop even after they spent a day in the same cage with an infected animal.
The work is published in the bioRxiv database (de Vries et al., Intranasal fusion inhibitory lipopeptide prevents direct contact SARS-CoV-2 transmission in ferrets) and sent for examination to the journal Science.
The fusion of viral and cell membranes is necessary for the penetration of SARS-CoV-2 into the cell. This process is mediated by the coronavirus S-protein, the refolding of which is necessary for successful infection. It has previously been shown that membrane refolding and fusion can be prevented with the help of so-called HRC peptides corresponding to the highly conserved S-protein domain with heptadic repeats. The authors of the new work proposed conjugating inhibitory HRC peptides with lipids and using the resulting lipopeptide as an intranasal drug against SARS-CoV-2. This strategy has already been tested on measles viruses, NPCs and human parainfluenza.
As a basis for SARS-CoV-2-specific lipopeptide, scientists took HRC-a peptide that reproduces an S-protein motif with a length of 36 amino acids. The inhibitory ability of several lipopeptide variants was tested using a cell membrane fusion analysis based on the complementation of β-galactosidase (β-gal). Cells expressing human ACE2 and the N-terminal fragment of β-gal were mixed with cells carrying the coronavirus S-protein and the C-terminal fragment of β-gal. During the fusion of two types of cells mediated by S-protein, two fragments of β-gal combine to form a catalytically active molecule. The fact that the fusion has occurred can be judged by the fluorescent signal that is formed when the substrate is cleaved by β-galactosidase. Membrane fusion was most effectively inhibited when cells were treated with dimerized HRC-peptide bound to cholesterol via a polyethylene glycol linker ([SARS HRC-PEG4]2-chol). At the same time, the lipopeptide was not toxic to cells.
The next step was to check the action of ([SARS HRC-PEG4]2-chol against live SARS-CoV-2. It has been shown that lipopeptide pretreatment of VeroE6 cells expressing TMPRSS2 protease prevents their infection with coronavirus. The efficacy has also been confirmed for ([SARS HRC-PEG4]2-chol in sucrose solution — such a formula is potentially suitable for human treatment.
For testing ([SARS HRC-PEG4]2-chol in vivo, scientists chose ferrets, since these animals successfully transmit SARS-CoV-2 to each other by air and by direct contact. During the experiment, uninfected ferrets were dripped with a solution ([SARS HRC-PEG4]2-chol in DMSO or 2% DMSO (control) for two days, and then one ferret infected with coronavirus was placed with them. After 24 hours, the ferrets were divided into groups (infected donor, group ([SARS HRC-PEG4]2-chol and control group), each group was kept separately. Recipient ferrets received an additional dose ([SARS HRC-PEG4]2-chol on the 3rd and 4th day of the experiment.
According to the results of PCR analysis of smears from the nose and throat of animals, ([SARS HRC-PEG4]2-chol gave a pronounced effect: 6 out of 6 ferrets who received the drug did not develop a viral infection. A blood test revealed the presence of antibodies to coronavirus in ferrets — donors of infection and in the control group. In animals treated with lipopeptide, antibodies were not detected, and there were no side effects associated with treatment.
Thus, prophylactic intranasal administration of lipopeptide ([SARS HRC-PEG4]2-chol prevents transmission from an infected animal to an uninfected one even after 24 hours of close contact. The authors believe that lipopeptide inhibitors can be easily adapted for the prevention of COVID-19 in the human population.
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