(Speaker Term: 7/1/12 - 6/30/14)
Department of Microbiology and Immunology (MC 790)
University of Illinois at Chicago
835 S. Wolcott Avenue
Chicago, IL 60612
Speaker's URL: http://www.uic.edu/depts/mcmi/faculty/freitag/index.htm
LECTURE TOPICS AND DESCRIPTIONS
The Listeria monocytogenes Transition from Environmental Bacterium to Human Pathogen
Many organisms inhabit soil and water, yet a relatively small percentage of these organisms have developed the capacity to cause human disease. L. monocytogenes, long used as a model for understanding innate and adaptive immune responses and various aspects of cell biology, also serves as a model for deciphering how a bacterium transitions from life in the soil to life within the cytosol. The Freitag Lab has been working to define how a key transcriptional regulator known as PrfA functions as the molecular switch that balances L. monocytogenes life as a saprophyte with life as an intracellular parasite.
Listeria monocytogenes Cardiac Infections: Acquisition of Novel Bacterial Replication Niches
L. monocytogenes has been associated with invasive infections that target the central nervous system or the placenta. The Freitag Lab has recently found that sub-populations of L. monocytogenes are capable of targeting heart cells, resulting in invasive cardiac disease. Ongoing work seeks to define the mechanisms by which pathogens such as L. monocytogenes develop the capacity to exploit novel host niches.
Listeria monocytogenes as a Model for Exploration of Gram-positive Virulence Factor Secretion
While extensive focus has been given to the processes of virulence factor secretion by Gram-negative bacteria, much less is known regarding how Gram-positive bacteria regulate the stability and activity of virulence factors once those factors have been translocated across bacterial cell membranes. The Freitag Lab has recently described a post-translocation secretion chaperone in L. monocytogenes known as PrsA2, located at the bacterial membrane-cell wall interface, that is essential for L. monocytogenes virulence. PrsA2 appears to have been specifically adapted to regulate the stability and activity of virulence factors whose secretion is induced following L. monocytogenes entry into the host cell cytosol. PrsA family members are found in many Gram-positive bacteria, and the study of PrsA2 function in L. monocytogenes provides an exceptional opportunity for understanding how Gram-positive bacteria regulate virulence factor secretion while maintaining cell membrane integrity.
How Anesthetics Increase Host Susceptibility to Bacterial Infection
Peri- and post-operative infections remain a critical problem that negatively impacts patient health. While it has been recognized that anesthetics can influence host immunity, the pathways of molecular cross-talk existing between the host central nervous system and immunity have not been well defined. Dr. Freitag is using L. monocytogenes as a model pathogen for the exploration of how propofol, a commonly used surgical anesthetic, increases host susceptibility to infection. L. monocytogenes has served for decades as a model organism for defining numerous aspects of the host immune response, thus the bacterium is an ideal tool for deciphering how CNS drugs can negatively impact host immunity in the context of microbial infection.
Chitinases as Bacterial Virulence Factors
A number of environmental bacteria express chitinases and chitin binding proteins, and these proteins facilitate the hydrolysis of chitin as an energy source and/or bacterial attachment to organisms such as insects, plankton, and shellfish. Although mammals do not synthesize chitin, it has recently been recognized for several environmental pathogens that chitinases can promote bacterial attachment and colonization of host epithelial surfaces. The Freitag Lab has found that a Listeria monocytogenes chitinase, ChiA, functions to suppress specific aspects of host innate immune responses and, thus, the enzyme functions to enhance bacterial persistence within infected tissues. These studies represent the first demonstration of a bacterial chitinase as a modulator of host innate immunity.
BIOGRAPHICAL SKETCH - Nancy E. Freitag, Ph.D.
Dr. Freitag has been continuously funded for her research on different aspects of Listeria monocytogenes pathogenesis for over 15 years. She is internationally recognized for her work on microbe-host interactions, and she has published more than 50 papers and book chapters while also serving as a member of journal editorial boards that include Infection and Immunity and Molecular Microbiology. Dr. Freitag has been a member or ad hoc member on numerous NIH study section panels, and she has served as an ad hoc reviewer for international foundations such as the Wellcome Trust. Dr. Freitag has been an invited speaker at more than 80 conferences, seminars, and colloquia, and has participated in a number of Science Career forums organized by various foundations, community colleges, and universities. She maintains an active interest in science education, and has been actively engaged in high school teacher and student science research mentoring programs. In addition, she has served for five years as an ASM judge for the Intel International Science and Engineering Fair.
CV is available by request from firstname.lastname@example.org at ASM Headquarters
ASM MEMBERSHIP AFFILIATION - Nancy E. Freitag, Ph.D.
Primary Division: B (Microbial Pathogens)
Secondary Division: D (Microbe-Host Interactions)