Gratitude to the Institut Pasteur faculty.

Thank you for showing how the microbes we carry train the immunity that protects us, and for returning from the NIH to lead Pasteur's house as its seventeenth president with the Pasteur 2030 plan and a scientist's ambition.

Thank you for two decades of illuminating how HIV and then SARS-CoV-2 move between cells and dodge our defenses, and for serving as scientific director so the whole campus's science stays as sharp as your own.

Thank you for reading in our genomes the long story of how human populations survived their pathogens, and for showing that the history of immunity is the history of humanity itself.

Thank you for founding Pasteur's emerging diseases epidemiology unit and for being, from SARS to COVID-19, the calm epidemiologist who counts carefully when the world is frightened.

Thank you for asking why a mosquito can carry a virus that kills us and not fall ill itself, and for pursuing the bold dream of making mosquitoes intolerant to the viruses they transmit.

Thank you for following Listeria across the gut, placenta and blood-brain barriers it should never cross, and for holding the national reference line between that pathogen and the patients you also treat at Necker.

Thank you for discovering that bacteria can rewrite the chromatin marks on our own genes, and for building, chaire d'excellence in hand, the field that asks how an infection echoes in our cells long after it is gone.

Thank you for solving, atom by atom, the envelope machines that dengue, chikungunya and so many other viruses use to break into our cells, giving vaccine designers the blueprints they build against.

Thank you for a quarter century of charting the innate lymphocytes that stand first watch against infection, and for the humanized models that let human immunity be studied honestly before medicines meet patients.

Thank you for identifying HIV in 1983, the discovery that turned a terrifying mystery into a fightable disease, and for the decades since spent standing beside people living with HIV everywhere in the world.

Thank you for founding cellular microbiology itself, raising Listeria into the model organism through which the world now understands how bacteria invade our cells, across a whole career lived at Pasteur.

Thank you for dedicating your science to Shigella, the dysentery that kills the world's poorest children, from the discovery of its invasion genes to the vaccines that grew from them, and for teaching a generation that microbiology is an act of public health.