Microbial Pathogenesis Research Laboratory
The Barger Lab
Our lab research sits at the nexus of microbial pathogenesis and aquatic animal health. The primary focus is the pathogenesis and control of infectious diseases in aquatic organisms, with a special emphasis on hypervirulent Aeromonas hydrophila.
Current Research
Investigating the virulence mechanisms of hypervirulent Aeromonas hydrophila and working to develop effective countermeasures against this pathogen. With the overarching goal of controlling virulent motile aeromonad septicemia (vMAS) in channel catfish, a disease with devastating impacts on the aquaculture industry, our lab usestranscriptomics, proteomics, and other molecular genetic techniques to discover what makes vAh transition from a member of the aquatic microbial consortia to primary pathogen.
Our lab is also exploring the differential gene expression of vAh in planktonic versus biofilm-associated states, a line of inquiry with significant implications for disease management in aquaculture.
Another key aspect of our research involves the innovative application of molecular techniques, including the construction of chromosomally integrated near-infrared fluorescent protein (iRFP) expression systems in A. hydrophila pathotypes. These methodologies allow real-time visualization of infection dynamics and provide valuable insights into host-pathogen interactions and the potential efficacy of therapeutic interventions.
The Team
Dr. Barger was introduced to the magical world of microbes as an undergraduate at Auburn University. Her research journey began in the Bacterial Physiology lab of Dr. Tom Pitta, where she studied gliding motility and virulence in the fish pathogen Flavobacterium columnare. This early exposure to aquatic pathogens led to a position as a research assistant in a fish health lab at the USDA-ARS Catfish Genetics Research Unit, where she gained hands-on experience in catfish husbandry and developed a deep appreciation for the complex interplay between aquatic ecosystems and animal health. This interest in aquatic ecology guided her master’s thesis, which focused on the population structure of Oscillatoria agardhii, a hypolimnetic cyanobacterium that produces a toxic metabolite affecting the taste of pond-raised and wild fish, as well as drinking water. This research further fueled her fascination with environmental microbiology and the complexity and connectivity of the aquatic ecosystem to terrestrial and aquatic animal health. These foundational experiences set the stage for her doctoral research, where she investigated the pathogenic mechanisms of hypervirulent Aeromonas hydrophila (vAh) in channel catfish. Her dissertation provided critical insights into the role of these virulence factors and how ecological adaptation drives the expression of specific genes linked to pathogenicity.
Allison Wise Addison: Doctoral student. Allison grew up in Catfish Country in the Mississippi delta, where her father taught her how to hold a pipette and a fishing pole at an early age. Allison spent her formative years working in fish disease labs and on the banks of catfish ponds. Allison earned her B.S. in Molecular Biology with a minor in French from Texas Lutheran University, where she was a two-sport athlete, playing soccer, and tennis. After completing her B.S., Allison earned her M.S. in Fisheries at Auburn University in the lab of Dr. Tim Bruce where she studied the effects of multi-species bacterial infections on catfish mortality. Allison joined the Barger lab as the inaugural Doctoral Student. She has a deep respect for the catfish producers and a passion for bridging basic bacterial disease research to develop real world solutions for producers. She is working to develop immunostimulants to protect fish against vAh, and exploring pathogenesis using real-time imaging.