Bird flu viruses are a serious concern for human health, and recent research has uncovered a worrying truth. These viruses can replicate at temperatures higher than a typical fever, a natural defense mechanism of our bodies. This discovery, led by scientists from the universities of Cambridge and Glasgow, sheds light on why bird flu poses such a significant pandemic threat.
The study, published in Science, identified a gene that determines a virus's temperature sensitivity. During the deadly pandemics of 1957 and 1968, this gene transferred into human flu viruses, leading to severe infections.
Human flu viruses, known as influenza A viruses, typically thrive in the upper respiratory tract, where temperatures are around 33°C. However, avian influenza viruses tend to infect the lower respiratory tract or even the gut, where temperatures can reach 40-42°C.
Fever, which can raise our body temperature to 41°C, is one of our body's ways to combat viruses. But here's where it gets controversial: avian flu viruses seem resistant to these fever temperatures.
The research team used mice infected with influenza viruses to understand how fever protects us and why it might not be effective against bird flu. They found that while fever stops human-origin flu viruses from replicating, it is less effective against avian flu.
And this is the part most people miss: the PB1 gene of the virus plays a crucial role in its temperature sensitivity. Viruses with an avian-like PB1 gene can withstand fever temperatures, causing severe illness. This gene swapping between human and bird flu viruses is a potential source of threat, as seen in previous pandemics.
Matt Turnbull, the study's first author, emphasizes the importance of monitoring bird flu strains and testing their resistance to fever. Sam Wilson, the senior author, highlights the high fatality rates of bird flu in humans and the need for understanding these viruses for pandemic preparedness.
The findings also raise questions about the treatment of infections. While fever is often treated with antipyretic medication, clinical evidence suggests that treating fever may not always benefit patients and could even promote the transmission of influenza A viruses.
This research provides valuable insights into the complex world of viruses and their interactions with our bodies. It underscores the need for continued research and surveillance to stay ahead of potential pandemic threats.
