by Susanne Stöcker, Paul-Ehrlich-Institut – Bundesinstitut für Impfstoffe und biomedizinische Arzneimittel
This digitally-colorized transmission electron microscopic picture depicts the ultrastructural particulars of an influenza virus particle. Credit score: CDC, Frederick Murphy
Critical infections with influenza A viruses are characterised by an extreme immune response, often called cytokine storm. It was beforehand unclear why some virus strains set off these storms, whereas others don’t. Researchers on the Paul-Ehrlich-Institut investigated 11 totally different influenza A virus strains and their impact on totally different human immune cells.
The outcomes, printed in Rising Microbes & Infections, present that extremely pathogenic avian influenza viruses infect particular sorts of immune cells and thus stimulate the manufacturing of sort I interferon. This might clarify why these viruses are notably harmful.
“Our research results show that not only the immune cells that have always been the focus of attention regarding type I interferon production, but also other immune system cells could be decisive in whether an influenza infection triggers an excessive immune system response. This knowledge is important in order to be able to better assess the risk of dangerous virus variants,” summarizes Professor Zoe Waibler, Vice President (appearing) of the Paul-Ehrlich-Institut.
Influenza viruses are a number of the most important respiratory illness pathogens worldwide. Whereas most infections are comparatively delicate, sure virus strains could cause extreme pneumonia, resulting in acute respiratory failure. Extremely pathogenic influenza viruses are notably harmful. They typically unfold from birds to people and are related to considerably greater mortality charges.
The immune system performs a vital function on this hazard: some virus strains trigger the physique to launch an extreme quantity of messenger substances often called cytokines. If a cytokine storm happens, the immune response will find yourself damaging the physique’s tissue greater than the virus itself.
Predominantly extremely pathogenic IAV an infection present productive an infection however lowered viability in immune cells aside from pDC. Credit score: Rising Microbes & Infections (2025). DOI: 10.1080/22221751.2025.2556718
However why do some influenza viruses set off such extreme reactions, whereas others solely trigger infections with delicate development? The analysis group, led by Dr. Martina Anzaghe, Analysis Immunology Part, sought to raised perceive this response.
Working along with the Virology Division on the College Hospital Freiburg, the group investigated 11 totally different influenza A virus strains—each frequent seasonal influenza viruses and extremely pathogenic avian influenza viruses. They examined how the flu viruses infect totally different immune cells and stimulate the discharge of messenger substances.
The intention of their analysis is to decipher the mechanisms behind delicate and extreme illness development and to develop long-term approaches for higher safety and therapy choices.
Key function performed by sure immune cells in extreme influenza
The investigations confirmed {that a} sure sort of immune cell, so-called plasmacytoid dendritic cells, produce giant quantities of the necessary antiviral messenger interferon-α (IFN-α) upon an infection with influenza—whatever the virus pressure. Because of this these immune cells typically reply strongly to influenza viruses with out the necessity for the virus to productively infect them.
If that is so, why don’t all viruses trigger the identical severity of the illness? The analysis group discovered that different immune cells, specifically myeloid dendritic cells and several types of macrophages, are contaminated with extremely pathogenic influenza viruses and produce giant quantities of IFN-α. Viral replication in these immune cells seems to be an necessary issue within the manufacturing of sort I interferon and the event of an extreme immune response (cytokine storm).
These outcomes present a proof of why some influenza viruses might be a lot extra harmful than others: it may be their capability to copy in sure immune cells and thereby set off a particularly robust immune response that results in extreme irritation and hurt to well being. This data may also help to develop focused therapies and higher determine threat teams.
Extra info:
Marc A. Niles et al, Influenza A virus induced interferon-alpha manufacturing by myeloid dendritic cells and macrophages requires productive an infection, Rising Microbes & Infections (2025). DOI: 10.1080/22221751.2025.2556718
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