7 July 2020 – In 2008, EMBO Member Luis Teixeira was screening fruit flies for genetic mutations that could make them more vulnerable to viral infection. But his postdoc project was not going to plan. “I was looking for innate immunity genes that might be antiviral, but it was clear something was terribly wrong – my control flies were dying faster than my mutant strains,” explains Teixeira, whose group studies host-microbe interactions at the Instituto Gulbenkian Ciência in Lisbon, Portugal.
After weeks fretting over his project, it occurred to Teixeira that although he had treated his flies with antibiotics to combat any interference from bacteria, that batch of mutant strains was not treated. He had read about a remarkable intracellular bacterium called Wolbachia and wondered now if the antibiotics in his control had killed off a key line of defence. “Wolbachia is exceptionally common in insect species: sometimes it’s pathogenic, sometimes it’s beneficial, but it did not seem to have strong effects in Drosophila melanogaster,” he explains. He decided to find out. “It was the difference between living and dying of viral infection.”
Wolbachia, it turned out, gives protection against viral foes not only to fruit flies, but also mosquitos. The work has informed studies led by others looking to spread Wolbachia in mosquitos to tackle vector-borne diseases such as dengue and yellow fever. Now, Teixeira continues to explore the mysteries of how hosts such as Drosophila interact on a functional and evolutionary level with microorganisms in nature – pathogenic or mutualistic. “Under every stone we turn there is something new,” he says. “It’s very exciting.”