New Jersey Scientists Warn That New Omicron Subvariants Like KP.3.1.1, XDK.1 Are More Cytopathic and Lethal in Coinfections
Nikhil Prasad Fact checked by:Thailand Medical News Team Jun 29, 2025 5 hours, 7 minutes ago
Medical News: Deadly New Omicron Subvariants Show Extreme Immune Evasion and Infectivity in Coinfections
Scientists at the Center for Discovery and Innovation at Hackensack Meridian Health in New Jersey have just sounded the alarm over a new wave of SARS-CoV-2 Omicron subvariants that appear far more dangerous than previously thought. These subvariants not only dodge immune responses from past infections and existing treatments but also become significantly more harmful when combined with other respiratory viruses like influenza and RSV.
In this
Medical News report, researchers discovered that the latest Omicron strains, especially the KP.3.1.1 subvariant, have evolved with new spike protein mutations that make them highly resistant to neutralizing antibodies. Neither commercial monoclonal antibodies nor plasma from unvaccinated individuals who recovered from earlier infections showed strong protection against these subvariants. Alarmingly, when these new subvariants infect lung cells alongside viruses like flu or RSV, the damage to lung tissue becomes significantly worse.
Omicron KP.3.1.1 Causes Severe Damage on Its Own
The team used an advanced laboratory model that mimics human bronchial airway cells to study both single infections and coinfections. The KP.3.1.1 subvariant showed more aggressive effects on lung cells than earlier strains like the original Washington strain (WA1/2020) or the earlier Omicron JN.1. It caused clear damage to the bronchial lining, more cell death, and a much stronger cytopathic effect, which is a scientific term for the visible destruction of infected cells.
More strikingly, when KP.3.1.1 was introduced together with Influenza A H1N1 or Respiratory Syncytial Virus (RSV), the severity of the infection increased. The coinfections did not reduce the strength of the SARS-CoV-2 variant—on the contrary, they made it more infectious and damaging.
Antibodies and Natural Immunity No Longer Work Well
The researchers tested several monoclonal antibodies that are either approved for use or commercially available, including bebtelovimab and casirivimab. While these antibodies worked well on earlier strains, their ability to neutralize newer Omicron subvariants like KP.3.1.1 had dropped significantly, with some showing less than 20 percent effectiveness.
Plasma taken from unvaccinated individuals who recovered from COVID-19 in 2020 also failed to stop the new variants. This means both natural immunity and antibody treatments might now be ineffective against these newer viral versions.
Spike Protein Mutations Behind the Dangerous Evolution
Genetic analysis showed that newer subvariants like KP.3.1.1 and XDK.1 have picked up new mutations in their spike proteins—parts of the virus that help it enter human cells. Some of these changes, such as Q183H, F456L, Q493E, and V1104L, make the virus better at avoiding detection by the immune system.
Interestingly, it is not the number of mutations but the specific locations and types that are enabling this dangerous shift in behavior. This suggests the virus is becoming smarter in how it mutates, focusing on areas that weaken the body’s defenses.
Higher Levels of Harmful Cytokines Detected
During infection
s, especially in coinfected cells, researchers noticed a sharp rise in harmful inflammatory proteins like IL-6, IFN-β, and IL-10. These are cytokines—chemical messengers used by the immune system. While they are necessary to fight infections, excessive levels can lead to inflammation and tissue damage. This may explain why coinfections involving the KP.3.1.1 subvariant lead to more severe respiratory issues.
Conclusion
The study paints a worrying picture of where SARS-CoV-2 evolution is heading. The emergence of KP.3.1.1 and related subvariants shows that the virus is not just surviving but thriving by outsmarting antibodies and exploiting coinfections to wreak even more havoc on the lungs. This development demands urgent updates to current vaccines, antibody treatments, and public health policies. More importantly, it reinforces the need for global monitoring of viral coinfections as these combinations could create health emergencies worse than COVID-19’s early days.
The study findings were published in the peer reviewed journal: Viruses.
https://www.mdpi.com/1999-4915/17/7/918
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