Megan T. Baldridge, MD, PhD

Associate Professor
Internal Medicine
Infectious Diseases
Molecular Microbiology

Molecular Microbiology and Microbial Pathogenesis Program
Molecular Genetics and Genomics Program
Immunology Program
Computational and Systems Biology Program

  • 314-273-1212

  • 314-273-1220

  • 832-236-4899

  • Room 4204, McKinley Research Building, 4515 McKinley McKinley Ave, St. Louis, MO 63110



  • microbiota, infection, pathogen, microbiome, virus, interferon, immunity

  • Defining the mechanisms behind and effects of the interactions between commensal bacteria, pathogens and innate immunity

Research Abstract:

The Baldridge lab is broadly interested in the complicated interplay between three important factors: commensal microbes, the host immune system, and viral and bacterial pathogens. Previous work has involved characterization of the intestinal commensal microbiota and interrogation of its role in regulation of both enteric viral infection and the host immune system. The coordination of next-generation sequencing efforts with in vivo infections and treatments in mouse models and organoids makes the exploration of transkingdom interactions possible. There are several main areas the Baldridge lab is currently pursuing:

1. Determine how the microbial exposome (both the commensal microbiome and pathogen exposures) influence the immune system, subsequent infectious or environmental challenges, and hematopoiesis.

2. Define specific commensal bacteria necessary and sufficient to regulate viral infection in the intestine.

3. Explore viral adaptation strategies to take advantage of commensal microbes and to infect at alternate host sites.

4. Understand how interactions between bacteria and bacteriophage may contribute to microbiota development and disease.

Mentorship and Commitment to Diversity Statement:
As a principal investigator, I strive to make my laboratory a welcoming and supportive environment for individuals of diverse cultural, racial, and ethnic backgrounds, and inclusive for members with a diversity of professional experience, religious and political beliefs, sexual orientations and ages. With an intentional focus on recruiting talented staff and trainees with varying backgrounds, I have been fortunate to bring together individuals with an array of different perspectives, opinions, and ideas, allowing us as a team to find innovative solutions to complex biological problems. While as a mentor, I am always seeking how to best support and motivate individual trainees, I have come to recognize that careful listening and providing as much empathetic understanding as I can is often the key to helping trainees feel included and encouraged. Serving as a mentor for trainees from underrepresented groups has offered me important opportunities to grow, including assessing my own implicit biases and assessing what I have to offer and where students would benefit from other sources of support or mentorship. I have previously and continue to seek out educational opportunities related to both mentoring and diversity and inclusion considerations, and have participated in formal mentoring workshops in 2019 and 2021, as well as in a four-part course offered by Washington University entitled “Diversity & Inclusion: Awareness, Understanding, Commitment, Action” in 2019.

Beyond my activities to improve my mentorship of individuals within my laboratory, I also seek to build a diverse and inclusive community at Washington University. As part of the Admissions Committee and now as a Co-Director for the Molecular Microbiology and Microbial Pathogenesis program, I have sought to both recruit a diverse range of students to our program as well as strongly support them during their training, and continue to work with various committees throughout the university to achieve a diverse and inclusive community of trainees. I recognize the importance of focused efforts at the individual, laboratory, and university levels to continue to enhance access to educational opportunities and supportive mentoring for our trainees from underrepresented backgrounds, and will continue to prioritize activities related to this ultimate goal.

Selected Publications:

Yan H, Walker FC, Ali A, Han H, Tan L, Veillon L, Lorenzi PL, Baldridge MT#, King KY#. The bacterial microbiota regulates normal hematopoiesis via metabolite-induced type 1 interferon signaling. Blood Advances 2022. 6(6):1754-1765. #co-corresponding

Van Winkle JA, Peterson ST, Kennedy EA, Wheadon MJ, Ingle H, Desai C, Rodgers R, Constant DA, Wright AP, Li L, Artyomov MN, Lee S, Baldridge MT#, Nice TJ#. Homeostatic interferon-lambda response to bacterial microbiota stimulates preemptive antiviral defense within discrete pockets of intestinal epithelium. Elife 2022. 11:e74072. #co-corresponding

Lawrence D, Campbell DE, Schriefer LA, Rodgers R, Walker FC, Turkin M, Droit L, Parkes M, Handley SA, Baldridge MT. Single-cell genomics for resolution of conserved bacterial genes and mobile genetic elements of the human intestinal microbiota using flow cytometry. Gut Microbes 2022. 14(1):2029673.

Lee S*, Kalugotla G*, Ingle H, Rodgers R, Wu C, Wang Y, Li Y, Yang X, Zhang J, Borella NR, Deng H, Droit L, Hill R, Peterson ST, Desai C, Lawrence D, Lu Q, Baldridge MT. Intestinal antiviral signaling is controlled by autophagy gene Epg5 independent of the microbiota. Autophagy 2021. *equal contribution

Ingle H, Hassan E, Gawron J, Mihi B, Li Y, Kennedy EA, Kalugotla G, Makimaa H, Lee S, Desai P, McDonald KG, Diamond MS, Newberry RD, Good M, Baldridge MT. Murine astrovirus tropism for goblet cells and enterocytes facilitates an IFN-λ response in vivo and in enteroid cultures. Mucosal Immunology 2021. 10.1038/s41385-021-00387-6.

Walker FC, Hassan E, Peterson ST, Rodgers R, Schriefer LA, Thompson CE, Li Y, Kalugotla G, Blum-Johnston C, Lawrence D, McCune BT, Graziano VR, Lushniak L, Lee S, Roth AN, Karst SM, Nice TJ, Miner JJ, Wilen CB#, Baldridge MT#. Norovirus evolution in immunodeficient mice reveals potentiated pathogenicity via a single nucleotide change in the viral capsid. PLOS Pathogens 2021: 17(3):e1009402. #co-corresponding

Grau KR, Zhu S, Peterson ST, Winesett E, Philip D, Philips M, Hernandez A, Turula H, Frasse P, Graziano VR, Wilen CB, Wobus CE, Baldridge MT#, Karst SM#. The intestinal regionalization of acute norovirus infection is regulated by the microbiota via bile acid-mediated priming of type III interferon. Nature Microbiology 2019: doi: 10.1038/s41564-019-0602-7. #co-corresponding

Ingle H*, Lee S*, Ai T, Orvedahl A, Rodgers R, Zhao G, Sullender M, Peterson ST, Locke M, Liu TC, Yokoyama CC, Sharp B, Schultz-Cherry S, Miner JJ, Baldridge MT. Viral complementation of immunodeficiency confers protection against enteric pathogens via interferon-λ. Nature Microbiology 2019: doi: 10.1038/s41564-019-0416-7. *equal contribution

Lee S, Wilen CB, Orvedahl A, McCune BT, Kim K, Orchard RC, Peterson ST, Nice TJ, Baldridge MT#, Virgin HW#. Norovirus Cell Tropism is Determined by Combinatorial Action of a Viral Non-structural Protein and Host Cytokine. Cell Host & Microbe 2017. 22(4):449-459. #co-corresponding

Moon C*, Baldridge MT*, Wallace MA, Burnham CD, Virgin HW, Stappenbeck TS. Vertically transmitted faecal IgA levels determine extra-chromosomal phenotypic variation. Nature 2015, 521(7550):90-3. * equal contribution

Baldridge MT, Nice TJ, McCune BT, Yokoyama C, Kambal A, Wheadon M, Lazear HM, Diamond MS, Ivanova Y, Artyomov M, Virgin HW. Commensal microbes and interferon-λ determine persistence off enteric murine norovirus infection. Science 2015, 347(6219):266-9.

Baldridge MT*, King KY*, Boles NC, Weksberg DC, and Goodell MA. Quiescent hematopoietic stem cells are activated by IFN-gamma in response to chronic infection. Nature 2010, 465: 793-797. * denotes equal contribution

Last Updated: 8/1/2022 1:18:34 PM

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