Profiles

Research in Johnson laboratory is focused on the molecular and cellular biology of the unicellular parasite Trichomonas vaginalis. This eukaryotic microbe is responsible for the most prevalent, non-viral, sexually transmitted infection worldwide and is the most common parasite found in the US population. An estimated 275 million people worldwide have the parasite, including about 3.7 million in the United States. In 2014 the Center for Disease Control and Prevention identified trichomoniasis, the infection caused by T. vaginalis, as a Neglected Parasitic Infection in the United States. Beyond its medical importance, T. vaginalis is a fascinating organism for conducting research on the evolution of key biological processes present in all eukaryotes: from microbes to humans. Molecular data reveal T. vaginalis as one of the most divergent eukaryotes studied to date, making it an excellent system for exploring both biological diversity and extreme conservation. These basic science studies dovetail readily with medically important aspects of T. vaginalis, as its divergent, atypical properties offer possible chemotherapeutic targets and vaccine candidates. Our laboratory has focused on five aspects of trichomonad biology: organelle biogenesis & evolution, regulation of gene expression, drug resistance, host:parasite interactions and genomics. Our interdisciplinary research program merges several disciplines, including structural & cell biology, biochemistry, post-genomic bioinformatics, evolution and medical sciences. In recent years, we have primarily focused on defining and elucidating critical pathogenic mechanisms that allow T. vaginalis to establish and maintain an infection. Studies include identifying both parasite and host cell surface molecules that play critical roles in host:parasite interactions. The roles of small vesicles, called exosomes, that are secreted by the parasite, and mediate cellular communication and assist in colonization and infectivity of the host, are also being characterized. How a bacterial symbiont frequently identified in clinical isolates of T. vaginalis affects infection and a novel mechanism (called trogocytosis) human neutrophils use to kill the parasite are also being investigated.