Influenza A infects its host by latching onto sialic acid molecules on the surface of lung cells, a binding step that is essential to the virus entering and replicating inside cells. Rather than trying to block the virus directly, researchers at Rensselaer Polytechnic Institute and collaborating institutions in South Korea took a fundamentally different approach: they built a decoy. The result is a nanoparticle therapy that mimics the virus’s own target, trapping influenza A and triggering its self destruction. In immune compromised mice, the treatment reduced influenza A mortality from 100 percent to 25 percent over 14 days. The findings were published in Nature Nanotechnology.
How the Nanoparticle Therapy Works Against Influenza A
To enter a cell, influenza A must first bind to sialic acid on the cell surface using a protein called hemagglutinin, then sever that bond using an enzyme called neuraminidase in order to release itself and replicate. Current treatments, including neuraminidase inhibitors and annual vaccines, target either the neuraminidase enzyme or specific hemagglutinin variants. Both approaches are vulnerable to the continuous antigenic evolution of the virus, which can render a given year’s vaccine ineffective or develop resistance to neuraminidase based drugs.
The nanoparticle therapy developed at Rensselaer exploits a feature of influenza A that does not change: all hemagglutinin variants must bind to human sialic acid. The team constructed a dendrimer, a spherical nanoparticle with branching arms extending from a central core, and coated the outermost branches with sialic acid ligands. When misted into the lungs, the dendrimer presents itself as an attractive target for the virus, drawing influenza A away from actual lung cells.
The Architecture That Makes Nanoparticle Therapy Effective
The geometry of the nanoparticle is critical to its function. Hemagglutinin occurs on the surface of influenza A in clusters of three, known as trimers. Through careful design and testing, the researchers found that a spacing of three nanometers between the sialic acid ligands on the dendrimer surface produced the strongest possible binding to these trimers. Once the virus binds to the tightly packed dendrimer, the neuraminidase enzyme cannot reach the attachment point to sever the connection, leaving the virus permanently trapped.
Once bound to the dendrimer, the virus faces a fatal problem. With millions of hemagglutinin trimers on its surface all attempting to bind to any available sialic acid, only a small number of links to the nanoparticle are needed to trigger the virus to discharge its genetic cargo prematurely. Unable to deliver that cargo into a host cell, the virus effectively self destructs.
A previous attempt using a less structured nanoparticle had failed because the particle proved toxic and could be inactivated by neuraminidase. The dendrimer architecture resolves both problems by providing a precisely engineered binding surface that neuraminidase cannot overcome.
Why Nanoparticle Therapy Could Work Beyond Influenza A
The implications of this nanoparticle therapy extend well beyond influenza. The sialic acid binding mechanism exploited by influenza A is also used by other viruses to gain entry into human cells, including Zika, HIV, and the parasite responsible for malaria. The same decoy strategy used here could in principle be adapted to target any pathogen that relies on sialic acid binding for infection, making this platform potentially applicable to a broad range of infectious diseases.
According to lead researcher Robert Linhardt, a glycoprotein expert and professor at Rensselaer, the therapy is particularly valuable in scenarios where conventional vaccines are not an option, such as exposure to an unanticipated influenza strain or treatment of immune compromised patients who cannot mount an adequate vaccine response. For these populations, a mechanism based approach that does not depend on immune system activation represents a meaningful clinical advance.
What Comes Next for Nanoparticle Therapy Research
The current study was conducted in immune compromised mice, and further research in additional animal models and eventually human trials will be required before this nanoparticle therapy can reach clinical use. The research team anticipates that refinements in dendrimer design and ligand spacing could further improve binding affinity and antiviral efficacy across multiple pathogen targets.
The broader principle demonstrated here, that mimicking a virus’s intended target rather than blocking its surface proteins can serve as an effective antiviral strategy, represents a meaningful conceptual shift in how infectious disease researchers approach treatment design.
To read more about infectious disease and antiviral research, visit the FOMAT blog. FOMAT conducts infectious disease clinical trials at sites across the United States. To learn more about active studies, visit FOMAT’s patient studies page.
For the full source, see the original article at DDDmag.com.