Giardia lamblia is a ubiquitous intestinal protozoan parasite that one of the most commonly isolated enteric pathogens in children less than 2 years old, reaching up to 90% cumulative incidence in some populations. G. lamblia infections are syndemic with malnutrition, the latter of which is responsible for an estimated 1/3 of childhood deaths and 60% of deaths due to diarrhea. Field studies demonstrate that G. lamblia associates with persistent diarrhea, and in some populations there is correlation with childhood stunting and impaired development. This career development award will use a newly developed C57Bl/6 murine model of persistent giardiasis to investigate mechanisms that lead to impaired growth following G. lamblia infection. Recent work has identified that the C57Bl/6 strain is susceptible t persistent infection following challenge with G. lamblia Assemblage B (H3) purified cysts (Bartelt, et al. JCI, 2013). Infection accentuates malnutrition in protein-energy deficiency, and associates with villus blunting. Furthermore, protein-energy deficiency alters the small intestinal inflammatory response (blunted IL-4 and IL-5 mRNA and relative diminishment of B220+ cells), despite a similar parasite burden. Collectively, these findings have led to the hypothesis that in this novel murine model of giardiasis and malnutrition, G. lamblia -enteropathy leads to growth faltering through intestinal inflammation and impaired epithelial cell homeostasis. This project will evaluate in vivo (C57Bl/6;G. lamblia purified H3 cysts) the resultant nutrient deficiencies i giardiasis (serum free amino acids (HPLC), minerals, and vitamins), the nutritional factors that influence G. lamblia disease (using current interventions for diarrhea and malnutrition), and the important inflammatory mediators and T-cell responses that alter epithelial cell homeostasis and growth in giardiasis. The outlined career development plan in this proposal will enhance the success of this project by combining graduate level course work with technical training and seminars and conferences focusing on mucosal immunology and enteric parasitic infections. Excellent mentorship will provide experimental expertise and scientific guidance creating a successful environment for the development of an independent clinician-scientist.

Public Health Relevance

G. lamblia is a globally ubiquitous pathogen that associates with persistent diarrhea and is syndemic with malnutrition. This research will add insight into mechanisms whereby G. lamblia induces growth failure. The focus will be on the role of malnutrition to promote growth failure through small intestinal inflammation and enteropathy. The results will be useful for unraveling the mechanisms of disease due to this common but enigmatic pathogen, understanding the consequences of nutritional deficiencies on mucosal inflammation, and improving strategies for mucosal repair in malnourished children and enteric diseases in general.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Clinical Investigator Award (CIA) (K08)
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Microbiology and Infectious Diseases Research Committee (MID)
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Wali, Tonu M
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University of Virginia
Internal Medicine/Medicine
Schools of Medicine
United States
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Nel, Jeremy S; Bartelt, Luther A; van Duin, David et al. (2018) Endemic Mycoses in Solid Organ Transplant Recipients. Infect Dis Clin North Am 32:667-685
Bartelt, Luther A; Bolick, David T; Mayneris-Perxachs, Jordi et al. (2017) Cross-modulation of pathogen-specific pathways enhances malnutrition during enteric co-infection with Giardia lamblia and enteroaggregative Escherichia coli. PLoS Pathog 13:e1006471
Rogawski, Elizabeth T; Bartelt, Luther A; Platts-Mills, James A et al. (2017) Determinants and Impact of Giardia Infection in the First 2 Years of Life in the MAL-ED Birth Cohort. J Pediatric Infect Dis Soc 6:153-160
Bartelt, Luther A; Swann, Jonathan R; Guerrant, Richard L (2016) Decoding Hidden Messages: Can Fecal Host Transcriptomics Open Pathways to Understanding Environmental Enteropathy? Cell Mol Gastroenterol Hepatol 2:114-115
Donowitz, Jeffrey R; Alam, Masud; Kabir, Mamun et al. (2016) A Prospective Longitudinal Cohort to Investigate the Effects of Early Life Giardiasis on Growth and All Cause Diarrhea. Clin Infect Dis 63:792-7
Bartelt, Luther A; Platts-Mills, James A (2016) Giardia: a pathogen or commensal for children in high-prevalence settings? Curr Opin Infect Dis 29:502-7
Bartelt, Luther A; Bolick, David T; Kolling, Glynis L et al. (2016) Cryptosporidium Priming Is More Effective than Vaccine for Protection against Cryptosporidiosis in a Murine Protein Malnutrition Model. PLoS Negl Trop Dis 10:e0004820
Bartelt, Luther A; Sartor, R Balfour (2015) Advances in understanding Giardia: determinants and mechanisms of chronic sequelae. F1000Prime Rep 7:62