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 identified trichomoniasis, the infection cased by T. vaginalis, as one of Neglected Parasitic Infections (NPIs) 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 man. The precise evolutionary history of the trichomonad lineage is still debated; nevertheless, 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. Over the years, our laboratory has focused on five aspects of trichomonad biology: organelle biogenesis & evolution, regulation of gene expression, drug resistance, host:parasite interactions and genomics. Systems used to explore unique properties of this human pathogen range from in vitro studies of protein targeting and organelle biogenesis to the analysis of genetically manipulated parasites and their interaction with host-derived cell lines, to obtaining the complete sequence of the T. vaginalis genome. Our interdisciplinary research program has merged several disciplines, including structural & cell biology, biochemistry, genomics, proteomics, bioinformatics, evolution and medical sciences. In recent years, we have narrowed our focus to defining and explaining critical pathogenic mechanisms that allow T. vaginalis to establish and maintain an infection. These studies include identifying parasite cell surface molecules that play a critical role in adherence and cytotoxicity to human epithelial cells and identifying host proteins that interact with the parasite and those that are modulated as a result of host:parasite interactions. Small vesicles, called exosomes, secreted by the parasite that appear to mediate cellular communication and assist in colonization of the host are also being characterized. We are also investigating a possible link between infection with T. vaginalis and prostate cancer; for news story see: http://www.bbc.com/news/health-27466853