EMBO Postdoctoral Fellowship for Bernhard Kramer

Viruses are tiny infectious agents that invade the cells of our bodies and can make us sick. When a virus infects a cell, it can hijack the cell’s machinery to copy itself extensively. This invasion can trigger our immune system’s defenses, but viruses are masters at evading detection. One way this happens is when two different strains of a virus infect the same cell. During this process, the two strains can swap parts of their genetic material, creating new virus strains with different characteristics. These novel strains are sometimes more infectious and can be harder to detect and to fight off by the immune system. Despite the advantage of exchanging genetic material in facilitating evolution, viruses make it difficult for each other to successfully infect the same cell. In fact, once one virus has infected a cell, infection by a second virus is actively inhibited. Researchers are curious about the coexistence of these events; they wonder how secondary infections are inhibited on one hand and how two virus strains manage to exchange genes on the other.

Observing the viruses’ every move

The EMBO Fellowship offers Kramer the opportunity to solve this paradox by using microscopy to visualize what happens when two viruses infect the same cell. He will expand on an existing microscopy technique to enable simultaneous visualization of two influenza viruses from the moment they enter the same cell all the way until they make new virus copies. Ongoing research by the Tanenbaum group showed that the duration of each step of a viral infection can vary. “Not every infection has the same dynamics. For example, one virus enters a cell and replicates its genetic material fast, but is slow in making new virus copies. While another virus enters a cell and starts with replication late, but can produce new copies as soon as it starts replicating,” Kramer explains. “How strongly the first virus can inhibit the second virus, could depend on these dynamics”. By following two viruses through each step of a viral infection, Kramer aims to unravel how the first infection influences the success rate of each step in the second infection.

Tracking viruses with barcodes

In the second part of his project, Kramer focuses on which infection dynamics allow two viruses to exchange parts of their genetic material and what type of new strains emerge from them. To answer these questions, he will develop an assay to trace the new virus strains back to the cell in which they were produced. Kramer: “With this barcoding assay we can determine which specific type of infection dynamics leads to highly virulent variants and which leads to slow or lazy variants that are not very efficient at infecting cells”. This project will give more insight into what happens when two influenza strains infect the same cell. Understanding how they evolve through exchanging genetic material is crucial for developing treatments and vaccines to combat infectious diseases like influenza.

About the EMBO Postdoctoral Fellowship

EMBO awards Postdoctoral Fellowships to excellent postdoctoral researchers throughout Europe and the world. The Fellowship supports the researcher for a period of up to two years. “In a way, the Fellowship offers intellectual freedom and acknowledgement that a specific idea is worth pursuing,” Kramer says.