The Department of Bioengineering is honoured to welcome Dr Calvin Tiengwe, Assistant Professor in Imperial’s Department of Life Sciences , for our first Black History Month Department Seminar. This is a special addition to our Department Seminar series and an opportunity to hear from an exceptional Imperial researcher working at the intersection of molecular parasitology, host–pathogen biology and global health. Refreshments and networking will take place after this seminar in RSM 3.24 How does a cell count to one? Mechanisms of immune evasion in African trypanosomes Abstract: A fundamental problem in infection biology is how a parasite selects one member of a gene family from thousands of possibilities. Another is how changes to the expressed surface protein enable the parasite to alter its recognition by host antibodies. We seek to understand how trypanosome parasites orchestrate these two processes to evade host immunity. Each parasite must express one variant surface glycoprotein (VSG) at a time from a repertoire of over 2,500 genes to form a dense protective surface coat. Switching the VSG coat allows trypanosomes to sustain chronic infections. However, the molecular basis for enforcing the singular VSG choice is not completely understood. I will describe two recent discoveries in this area. First, I will discuss the identification of ESBX, a key molecule required for full activation of the active VSG expression site and repression of silent sites, providing insight into how this singular gene choice is enforced. Next, I will describe a second source of variation at the trypanosome surface: the modification of VSGs with a simple set of sugar molecules that generate diversity in antibody epitopes. We identified ESAG3, the long-sought enzyme responsible for adding these sugars, and determined its cryo-electron microscopy structure, revealing an unusual 18-subunit molecular machine. I will also show how the sugars it adds influence antibody recognition. Together,

Description supplied by the event organiser.