Researchers from the US National Institutes of Health identified unusual antibodies that interact with neuraminidase, a distinctive enzyme on the surface of influenza viruses. These antibodies target a less-explored region near the hemagglutinin area, a site that plays a key role in how the virus attaches to and enters human cells. The findings were published in Immunity, a respected scientific journal, adding a new perspective on how the immune system can recognize and potentially stop flu infections.
Current influenza vaccines primarily focus on hemagglutinin, the sugar-shaped protein responsible for binding viruses to human cells. Hemagglutinin can change rapidly from season to season, which is why vaccines are reformulated annually to match circulating strains.
Experts note that the so-called dark side of neuraminidase mutates more slowly and tends to remain more consistent across different influenza strains. This relative stability makes it an appealing target for broad protection against diverse flu viruses.
In the study, scientists analyzed blood samples from two individuals infected with the H3N2 subtype of influenza A, a strain that spreads each season and undergoes rapid mutations. From these samples, the researchers identified six antibodies that bind to the conserved region near neuraminidase. Laboratory tests showed that these antibodies attached to a range of H3N2 viruses and slowed the viruses’ replication. Notably, the antibodies also demonstrated activity against another influenza A strain, H2N2, suggesting cross-strain effectiveness.
In mouse experiments, the antibodies provided strong protection against a lethal dose of H3N2. This outcome implies potential for these antibodies to help prevent or treat influenza in humans. Protection was observed whether the antibodies were given before exposure to the virus or after infection, indicating both preventive and therapeutic potential.
Further testing revealed that the antibodies maintained their protective effect against certain drug-resistant flu strains. This resilience suggests that such antibodies could offer an additional line of defense when antiviral drugs are less effective due to resistance.
The research underscores the importance of exploring conserved, slower-changing targets on influenza viruses. By focusing on stable regions that remain more constant across different strains, scientists may develop therapies or vaccines capable of providing broader protection than current formulations.
Overall, the study demonstrates that antibodies targeting conserved sites near neuraminidase and hemagglutinin can curb viral spread in laboratory settings and provide meaningful protection in animal models. While further work is needed to translate these findings into human vaccines or treatments, the results represent a promising step toward more universal strategies for preventing seasonal flu infections and mitigating outbreaks.
These discoveries add to the growing body of evidence that the immune system can be steered toward recognizing conserved viral features. Such an approach could complement existing vaccines and antiviral drugs, potentially reducing the impact of flu seasons and improving preparedness for future influenza pandemics.