Can the Flu and Other Viruses Cause Neurodegeneration?

https://www.the-scientist.com/features/can-the-flu-and-other-viruses-cause-neurodegeneration--65498


also highlights via Amy Proal on Twitter:
https://twitter.com/user/status/1104122023746318341

 

Interesting in that article how influenzavirus H1N1 (swine flu) was not able to cross the blood-brain barrier and infect the brain, but influenzavirus H5N1 (bird flu) was able to.

 

Evolutionary factors? Just guessing but, pigs being mammals, we might have developed similar protective systems and blood brain barriers whereas birds have a different set of protections which means our mammal bodies are not as well adapted to resist or limit the virus once it has managed to find a way in.
Also I imagine that novelty and rate of change are factors: most bird flu cannot infect a human. The ones that do are special, particularly virulent?

 

I don't know; it may just be a quirk of the influenzavirus subtype and viral genetic makeup that determines whether it can cross the blood-brain barrier. There are dozens of subtypes, so you'd have to test them all to see if there's any trend.



It's interesting that during the 1957 influenzavirus H2N2 (Asian flu) pandemic, Prof Gottfries in Sweden observed hundreds of cases of ME/CFS that appeared after getting the flu. If it was the H2N2 virus that caused these ME/CFS cases, perhaps it did so because the virus was able to cross the BBB?

But I have not seen any solid evidence that influenzavirus infection can lead to ME/CFS. It's true there were many ME/CFS cases in Sweden during the 1957 influenza epidemic, but it's possible there might have also been an enterovirus outbreak running at the same time, and enterovirus often causes a flu-like illness which may be mistaken for influenza, especially during an influenza epidemic.