Dr. Ethel Bayer Santos is a FAPESP Young Investigator Fellow working at the Department of Microbiology at the University of Sao Paulo. She completed her PhD in 2013 under the supervision of Prof. Jose Franco da Silveira at the Federal University of Sao Paulo and Prof. Igor C. Almeida at the University of Texas at El Paso, studying the secretion pathways of the protozoan parasite Trypanosoma cruzi. She moved to Imperial College London to work as a postdoctoral fellow in the group of Prof. David W. Holden and identified the molecular mechanism of the Salmonella T3SS effector that suppresses T cell activation via MHCII downregulation. Ethel returned to Brazil and joined the group of Prof. Chuck Farah at the University of Sao Paulo where she characterized the function of Xanthomonas T6SS and Stenotrophomonas T4SS. In 2018, Dr. Bayer Santos became a FAPESP Young Investigator and joined the Laboratory of Protein Structure and Evolution (LEEP), led by Prof. Cristiane Rodrigues Guzzo Carvalho and Prof. Robson Francisco de Souza, to start her own research group, focused on understanding the fundamental mechanisms that allow pathogenic bacteria to subvert the function of innate immune cellsand survive within infected hosts.

Bacterial secretion systems are versatile structures that can secrete proteins into prokaryotic and eukaryotic cells. Many pathogenic bacteria rely on secretion systems to modulate host responses or to defend themselves against competing organisms and environmental predators. The type VI secretion system (T6SS) is evolutionarily related to the contractile bacteriophage tail and injects bacterial toxins into target cells. Serotypes of Salmonella entericacomprise facultative intracellular bacteria responsible for causing infections in several vertebrates. In humans, Salmonellacauses diseases ranging from gastroenteritis to typhoid fever. Salmonellosis is one of the most common zoonotic disease spreading between animals such as chicken/cattle and humans, with significant economic and health implications. Using a combination of microscopy, proteomics, cellular, molecular and structural biology, we plan to elucidate the molecular mechanisms by which proteins delivered across host membranes via T6SS contribute to subvert host cell responses and ultimately the pathology of infection. This fundamental research will increase our understanding of the mechanisms Salmonellaand other intracellular pathogens use to survive inside our first line of defenses and coordinate its dissemination inside infected hosts.