(2) Mitosis causes vRNPs to be distributed over two separate sister cells. Therefore, these sister-cells often end up having incomplete sets of genome segments. We termed this “viral aneuploidy”, akin to chromosome segregation errors occurring during host cell division.

We wondered why so many infections fail to progress through all life-cycle stages. We combined our live-cell imaging technologies with multiplexed smFISH and found that many viruses fail to transcribe one or multiple genes.

To capture the late-stage event of new virions budding off, we developed a second, orthogonal technique that visualizes the build-up of HA-protein on the cell surface of infected cells and even labels budding virions.

Further we can follow IAV over time and observed vRNPs replicating and later getting exported from the nucleus to allow assembly of new virions.

Using this technology we show for the first time the moment that virions fuse with the endosomal membrane and release vRNPs step-by-step into the host cell

The NP nanobody recognizes a broad range of IAV strains, including swine, avian, and human strains, and even viruses directly isolated from patient samples! Since there is no need to genetically modify the viruses, it is very easy to do experiments with new strains and isolates.

Influenza viruses are segmented, negative-sense RNA viruses that, like other (-)RNA viruses, have their genomes encapsidated by nucleoproteins (NP). We exploited this characteristic to visualize single, unmodified IAV genomes by expressing a fluorescently labelled nanobody that binds to NP.

Very happy to share our preprint on visualizing the life cycle of Influenza viruses using single-molecule imaging! 🥳 We developed two techniques to visualize infections of unmodified influenza viruses in live cells from endosomal release to budding of new viruses. For more details&videos see below ⬇️