In Lisbon, a team of scientists has uncovered a more intricate truth about how SARS-CoV-2 enters the human cell — not through a single forced intrusion, but through a coordinated two-step mechanism embedded in the virus's spike protein. The discovery, published in the Journal of Virology, reveals that two distinct fusion peptides work in sequence, the first establishing contact and the second destabilizing the membrane from within. In mapping this molecular choreography, researchers have not only deepened our understanding of one virus, but may have illuminated a shared vulnerability across an
Scientists identify two 'molecular keys' SARS-CoV-2 uses to breach cell membranes
The virus has a more complex fusion mechanism than expected
Mark
So they found two keys instead of one. What changes about how we think about stopping the virus?
Mimi
It means there are now two distinct targets instead of one. If you can block either key, you might prevent the virus from entering the cell. Before, we thought of it as a simpler lock-and-key problem. Now we know the virus has a more complex strategy.
Luke
But has anyone actually tested whether blocking one key or the other would work? The study identifies the keys—does it show they can be disabled?
Mimi
The paper identifies the mechanism and demonstrates their role in fusion. Testing whether blocking them is therapeutically viable would be the next step.
Mark
And the fact that this might apply to other coronaviruses—how confident are they about that?
Mimi
They found that the peptide sequences are conserved across various coronaviruses. If the structure is similar, the mechanism likely is too. But that's an inference based on genetic similarity, not yet proven experimentally.
Luke
Right. So it's a promising lead for future research, but not yet a solution.
Mimi
Exactly. This is foundational work. It answers the question of how the virus gets in. The next question is how to stop it.
Mark
How long until we might see a drug based on this?
Mimi
That's impossible to say. Drug development from a basic discovery like this typically takes years, sometimes a decade or more.
Luke
And there's no guarantee it will work. Viruses are clever at finding workarounds.
Mimi
True. But understanding the mechanism is the first step. You can't block what you don't understand.
Il Polso
- Scientists had long assumed a single mechanism drove SARS-CoV-2 into human cells — that assumption has now been overturned by evidence of a two-peptide entry system far more sophisticated than expected.
- The virus operates like a lockpick with two teeth: the first peptide anchors to the host cell membrane, and the second drives deeper to destabilize it, triggering the fusion that allows infection to begin.
- A multi-institutional team in Lisbon combined computational modeling, biophysical analysis, and virology to see what no single discipline could have revealed on its own.
- The discovery opens a therapeutic window — drugs targeting these fusion peptides could potentially neutralize not just SARS-CoV-2 but other coronaviruses that share the same molecular architecture, reshaping how broad-spectrum antivirals are designed.
In Lisbon, a team of scientists has uncovered a more intricate truth about how SARS-CoV-2 enters the human cell — not through a single forced intrusion, but through a coordinated two-step mechanism embedded in the virus's spike protein. The discovery, published in the Journal of Virology, reveals that two distinct fusion peptides work in sequence, the first establishing contact and the second destabilizing the membrane from within. In mapping this molecular choreography, researchers have not only deepened our understanding of one virus, but may have illuminated a shared vulnerability across an entire family of pathogens — offering humanity a more precise set of tools with which to prepare for what comes next.
Researchers at ITQB NOVA in Lisbon have mapped a previously misunderstood mechanism at the heart of coronavirus infection: SARS-CoV-2 does not force its way into human cells through a single molecular action, but through two distinct fusion peptides embedded in its spike protein, working in deliberate sequence.
The first peptide makes initial contact with the host cell membrane, securing a foothold. The second then inserts itself deeper into the membrane's structure, destabilizing it from within — and it is this destabilization that triggers the actual fusion between viral and cellular membranes, allowing the virus to cross inside. Lead author Carolina Buga describes it not as a battering ram but as a two-toothed lockpick, each tooth essential for the lock to turn.
The discovery was made possible by combining computational modeling, biophysical analysis, and virological investigation across four institutions, including the Faculty of Medicine at the University of Lisbon and the Gulbenkian Institute for Molecular Medicine. Study leader Diana Lousa credits this convergence of disciplines for revealing what no single approach could have uncovered alone.
The implications reach well beyond SARS-CoV-2. If this two-key fusion model is shared by other coronaviruses with similar peptide sequences, it could serve as a blueprint for understanding an entire pathogen family — and for developing broad-spectrum antiviral treatments capable of defending against future coronavirus threats, including those not yet known to infect humans.
A team of researchers at ITQB NOVA in Lisbon has mapped out precisely how the coronavirus breaches the walls of our cells—and the answer is more intricate than scientists had previously understood. The virus does not rely on a single mechanism to force its way in. Instead, it deploys two distinct molecular tools, both embedded in the spike protein that crowns the virus's surface, working in tandem to pry open the cell membrane and slip inside.
When SARS-CoV-2 approaches a target cell, its outer membrane must fuse with the cell's own membrane to allow the virus to enter. This fusion does not happen by accident or brute force. It requires precision. The spike protein contains what researchers call fusion peptides—molecular keys that unlock the cell's defenses. Carolina Buga, the lead author of the study published in the Journal of Virology, explains that the virus carries not one key but two. One sits at the N-terminal end of the spike protein; the other is positioned deeper within the protein's structure. Both are essential. Both must function in concert.
The choreography is elegant and deliberate. The first peptide makes initial contact with the host cell membrane, establishing a foothold. Once that contact is secured, the second peptide moves into position, inserting itself deeper into the membrane and destabilizing its structure from within. This destabilization is the critical moment—it is what triggers the actual fusion between the two membranes and allows the virus to cross the threshold into the cell. The discovery reveals that the virus has evolved a more sophisticated entry mechanism than researchers had previously credited it with. It is not a battering ram but a lockpick with two teeth, each one necessary for the lock to turn.
The research emerged from a collaboration that brought together computational modeling, biophysical analysis, and virological investigation. Diana Lousa, who led the study, notes that it was precisely this combination of approaches—different ways of seeing the same problem—that made the discovery possible. The team included researchers from ITQB NOVA, the Faculty of Medicine at the University of Lisbon, the Gulbenkian Institute for Molecular Medicine, and the Católica Biomedical Research Center. Each discipline contributed its own lens, and together they revealed something that no single perspective could have uncovered alone.
The implications extend beyond understanding how one virus works. If this two-key fusion model is common to other coronaviruses that share the same peptide sequences, then this discovery becomes a blueprint for understanding an entire family of pathogens. That possibility carries weight in the context of pandemic preparedness. A therapeutic strategy that targets these fusion peptides might not work only against SARS-CoV-2 but could potentially be effective against future coronavirus threats. The researchers believe this finding could inform the development of broad-spectrum antiviral treatments and shape how public health systems prepare for and respond to emerging coronavirus variants and novel coronaviruses yet to jump from animals to humans.
Citazioni salienti
The two keys act together and are necessary to promote membrane fusion during the virus's entry into the cell— Carolina Buga, first author of the study, ITQB NOVA
It was the combination of these different perspectives that allowed us to identify the two peptides and demonstrate the role they play in membrane fusion— Diana Lousa, researcher who led the study
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