Raphael H. Valdivia

My laboratory is interested in microbes that influence human health, both in the context of host-pathogen and host-commensal interactions. For many pathogens, and certainly for most commensal microbes, we have an incomplete molecular understanding of how host and microbial factors contribute to health and disease. My research group focuses on two experimental systems:

Chlamydia trachomatis infections are responsible for the bulk of sexually transmitted bacterial diseases and are the leading cause of infectious blindness (trachoma) in the world. Chlamydia  resides within a membrane bound compartment (“inclusion”). From this location, the pathogen manipulates the cytoskeleton, inhibits lysosomal recognition of the inclusion, activates signaling pathways, re-routes lipid transport, and prevents the onset of programmed cell death. Our laboratory focuses on identifying and characterizing the bacterial factors that are secreted into the host cell cytoplasm to manipulate eukaryotic cellular functions. We use a combination of cell biology, biochemistry, genetics, genomics, proteomics and molecular biology to determining the function of virulence factors that reveal novel facets of the host-pathogen interaction. Our goal is to understand how these obligate intracellular bacterial pathogens manipulate host cellular functions to replicate, disseminate and cause disease, and in the process develop strategies to ameliorate the damage caused by these infections to the female reproductive organs.

Akkermansia muciniphila is prevalent member of the gut microbiota that proliferates in the mucus layers of our lower gastrointestinal tract and contribute to nutrient homeostasis and human immunological health. My research group developed genetic tools to characterize these microbes to define the mechanisms used to colonize the human gut and identify the molecular and cellular pathways that underscore Akkermansia's impact on immune homeostasis.  In the process, we seek to engineer strains of Akkermansia that enhance their probiotic potential.