As a group of infectious agents, viruses can cause different forms of disease, from the common cold to more severe illnesses such as HIV and COVID-19. Unfortunately, experts find it hard to develop antiviral therapies because viruses can rapidly mutate and develop drug resistance. One of the critical features of this pathogen is its membrane, a bubble-like structure that helps the virus infect its host cells.
A team of experts from New York University created a new generation of antiviral drugs that ignores the rapidly mutating proteins on the pathogen's surface and instead attacks their protective layers.
Challenges in Fighting Viral Infections
The outer surfaces of viruses are composed of various proteins, which are often the targets of drugs such as monoclonal antibodies and vaccines. However, this approach has limitations since the viruses can evolve quickly, and the changes in the properties of these proteins make the therapeutics less effective. These limitations significantly impacted the COVID-19 pandemic when the emerging SARS-CoV-2 variants evaded the drugs and the vaccines developed to fight the virus.
According to Kirshenbaum, there is an urgent need to create antiviral agents that can act in new ways to turn off viruses. Ideally, the new antiviral agents will not be particular to only one virus or protein, so they can be readily available when new viruses emerge. Developing such a kind of drug can be inspired by the mechanism of our immune system.
In humans, the body's immune system fights pathogens by creating antimicrobial peptides, which act as the first defense against microorganisms. Since most disease-causing viruses are covered in lipid-based membranes, the antimicrobial peptides work by disturbing or bursting these membranes.
Antimicrobial peptides can be synthesized in the laboratory. Still, they are rarely used in treating infectious diseases because they can easily break down and become toxic to healthy cells. Because of this challenge, scientists develop synthetic materials called peptoids. These biochemicals resemble the chemical framework of peptides but can effectively break through virus membranes and have less tendency to degrade.
How Do Peptoids Work?
Led by chemistry professor Kent Kirshenbaum, the researchers from New York University focused on the vulnerability of a virus' bubble-like membranes. They thought of mimicking natural peptides and developing a type of molecule with similar structural and functional features.
In this study, the researchers investigated seven peptoids affecting four viruses. The three of them - Rift Valley fever, Zika, and chikungunya - were enveloped in membranes, while the other one - coxsackievirus B3 - was not. The scientists mainly chose these viruses because they have no available treatment options.
The membranes that cover the viruses are made of molecules other than the virus itself. One of them is a lipid called phosphatidylserine which is isolated toward the interior of human cells. From the result of the study, it was found that the seven peptoids inactivated all three viruses enveloped in membranes, but they did not affect the only one without a membrane.
Since phosphatidylserine is found on the outer part of the virus, it can be a particular target for peptoids but does not play a role in recognizing the pathogen. As the virus acquires lipids from the host rather than encoding them from their genes, they demonstrate better potential in preventing antiviral resistance. This suggests the contribution of phosphatidylserine in reducing viral activity.
Kirshenbaum and his team continue to study the potential of peptoids in fighting viruses and their mechanism in developing drug resistance. They hope their approach can provide the key to treating a wide range of diseases caused by viruses with membranes that can be difficult to treat.
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