Patricia J. Johnson, Ph.D.

Distinguished Professor


4610C MSB, 148906


Professor, Microbiology, Immunology & Molecular Genetics
Member, Immunity, Microbes & Molecular Pathogenesis GPB Home Area

Research Interests

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. 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, 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:
T.vaginalis is the most common non-viral sexually transmitted infection affecting ~275 million people/yr worldwide and 3.7 million in the US. In 2014 the CDC identified trichomoniasis, the infection caused by T. vaginalis, as one of the Neglected Parasitic Infections (NPIs) in the United States.

About T.vaginalis Infection:

  • Infections are often asymptomatic but those that are symptomatic often result in vaginitis, urethritis, or prostatitis 
  • Infection increases risk of HIV transmission
  • Long-term infections lead to severe consequences such as increased risk of cervical cancer, prostate cancer, pre-term birth, and infertility
For more info, visit the CDC Trichomoniasis Fact Sheet
About the parasite:
  • T.vaginalis is a flagellated, extracellular protozoan parasite
  • Attachment and cytolysis are important in pathogenesis
  • Surface and secreted proteins are implicated in host-pathogen interactions