Is apoptosis then required for IAV direct cell to cell spread? Well, not only do IAVs frequently undergo direct cell to cell spread, but this can almost be completely prevented with the inhibition of apoptosis! N/10

💡we found that whilst apoptosis alone had no effect, TLS induction by IAVs required both virus replication and the onset of apoptosis. Overall, our data reveals that apoptosis induced through IAV replication is responsible for the triggering of TLSs. N/9

🔍Clue 3: the induction of TLSs correlated with the onset of apoptosis. Furthermore, inhibition of apoptosis prevented the ability of IAVs to induce TLSs. However, induction of apoptosis with drugs, independent of infection, did not induce TLS formation. N/9

🔎Clue 2: induction of TLSs was consistent between IAV strains having either filamentous or spherical virion morphologies. This was in despite of several curious similarities between TLSs and budding IAV filaments. N/8

🔎Clue 1: the induction of TLSs did not occur through the release of paracrine innate immune signals, but did require intracellualr IAV replication. N/7

Firstly, we wanted to see if these structures formed at the natural site of IAV infection. We collaborated with the wonderful Ed Roberts lab and we could see, for the first time, evidence of TNT-like structures (TLSs) forming from infected cells within the lungs of mice. N/5

One mechanism of IAV direct cell to cell spread in vitro is through the formation of long, thin and fragile membrane connections known as Tunnelling Nanotubes (TNTs). Impressively, IAVs trigger the formation of TNTs but it was unknown how they were doing this. N/4

Direct cell to cell spread of IAVs describes the mechanisms that deliver viral genomes to new cells, independent of a cell free virus particle. This can allow infection spread even in the presence of antiviral drugs and neutralising anitbodies. N/3

Thanks to everyone who came along to the Virus-Host interactions forum today at Microsoc 2025! A privilege and pleasure to present my PhD work with @socialinfluenza.bsky.social @cvrinfo.bsky.social. A story, which has grown and taken me on a crazy Flu ride that I hope is just starting!