Nikhil Prasad Fact checked by:Thailand Medical News Team Dec 24, 2024 15 hours, 30 minutes ago
Medical News: Amid rising concerns over the potential pandemic threat posed by the highly pathogenic avian influenza (HPAI) virus subtype H5N1, researchers have conducted a groundbreaking study to better understand immune responses to this virus. The study, led by scientists from the La Jolla Institute for Immunology, Erasmus University Medical Centre, and the Icahn School of Medicine at Mount Sinai, analyzed the similarities between human immune responses to seasonal influenza viruses and H5N1. By leveraging data from the Immune Epitope Database (IEDB), they sought to determine whether pre-existing immune memory could offer protection against H5N1 infections.
Conserved Human T Cell Responses to H5N1 Influenza
Frequent spillovers of H5N1 into poultry, mammals, and even humans have raised alarms. Unlike seasonal influenza, which causes mild to moderate symptoms in most cases, H5N1 infections are often severe, with a case fatality rate exceeding 50%. Concerns have heightened due to reports of transmission among mammals, which could signal an increased risk of human-to-human transmission. This
Medical News report explores the study’s findings on the extent of T-cell cross-reactivity between seasonal and avian influenza viruses and what they mean for pandemic preparedness.
Understanding T Cell Cross-Reactivity
T cells play a critical role in the immune response by targeting and destroying virus-infected cells. For influenza, both CD4 and CD8 T cells are essential. The researchers focused on identifying conserved epitopes - specific parts of a virus that the immune system recognizes - across seasonal and avian influenza strains. This conservation is key to determining whether the immune system can respond effectively to a novel strain like H5N1.
Using data from over 2,000 immune assays, the study analyzed 486 epitopes, focusing on their conservation and immunodominance. This analysis revealed that many epitopes recognized by human T cells in seasonal influenza strains were also present in H5N1. Specifically, 57% of CD4 T-cell epitopes and 63% of CD8 T-cell epitopes were either identical or conserved to a degree associated with cross-reactivity. The findings suggest that pre-existing T-cell immunity could provide partial protection against H5N1, potentially blunting disease severity.
Experimental Validation of Cross-Reactivity
To validate these observations, the researchers synthesized dominant T-cell epitopes from both seasonal and H5N1 influenza strains. These epitopes were pooled into distinct groups for experimental testing. Blood samples from 20 healthy individuals were exposed to these epitope pools, and the immune responses were measured.
The results were striking. T cells from the participants responded similarly to both seasonal and H5N1 epitopes, indicating robust cross-reactivity. For CD4 T cells, markers of activation and cytokine production were comparable between the two groups of epitopes. Although CD8 T-cell responses were slightly less pronounced, they still demonstrated significant cross-reactivity.
I
mplications for Pandemic Preparedness
These findings offer a glimmer of hope in the face of a potential H5N1 pandemic. The study’s results suggest that previous exposure to seasonal influenza - whether through infection or vaccination - may provide some level of immunity to H5N1. This cross-reactivity could help mitigate disease severity, reducing hospitalization and mortality rates.
However, the researchers caution that cross-reactivity is not synonymous with complete protection. While T-cell responses can limit disease severity, they do not prevent infection. Vaccines specifically targeting H5N1 may still be necessary to achieve broader immunity.
Key Study Highlights
-Epitope Conservation:
57% of CD4 and 63% of CD8 T-cell epitopes from seasonal influenza are conserved in H5N1. This level of conservation suggests significant potential for cross-reactive immune responses.
-Experimental Findings:
T cells from healthy individuals responded robustly to both seasonal and H5N1 epitopes. CD4 T-cell responses were particularly strong, highlighting their role in cross-reactive immunity.
-Population Coverage:
The study’s analysis indicates that 84% of the global population has T cells capable of recognizing conserved H5N1 epitopes. This broad coverage underscores the potential for pre-existing immunity to mitigate a pandemic.
Conclusions and Future Directions
This study sheds light on the interplay between seasonal and avian influenza immunity, offering valuable insights for pandemic preparedness. The identification of conserved T-cell epitopes underscores the importance of monitoring and leveraging cross-reactive immune responses. It also highlights the need for further research into targeted vaccines that can enhance these protective effects.
Looking ahead, the researchers recommend strategies to focus immune responses on conserved and immunogenic regions of the virus. Such an approach could not only bolster defenses against H5N1 but also against other emerging influenza strains. By enhancing our understanding of immune cross-reactivity, we can better prepare for the next influenza pandemic.
The study findings were published in the peer-reviewed journal: mBio.
https://journals.asm.org/doi/10.1128/mbio.03479-24
For the latest H5N1 News, keep on logging to Thailand
Medical News.
Read Also:
https://www.thailandmedical.news/news/australian-scientist-claim-that-the-global-population-is-equipped-to-fight-h5n1-infections-via-cd8-t-cells
https://www.thailandmedical.news/news/reassorted-strain-of-h5n1-bird-flu-virus-discovered-in-cambodia
https://www.thailandmedical.news/articles/h5n1-avian-flu
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