Unraveling the biology of human pathogens is fundamental toward understanding mechanisms of pathogenesis and identifying genes essential for survival in the host. This application focuses on the protozoan parasite Trypanosoma brucei, which causes devastating diseases in humans and animals in sub-Saharan Africa. There are no vaccines, and therapeutic drugs have serious side effects and decreasing efficacy. T. brucei undergoes a complex life cycle between the mammalian host and the blood-feeding tsetse fly vector (Diptera: Glossinidae), which among others involves changes in cell morphology, metabolism, signaling pathways and gene expression. Consequently, these parasites have evolved adaptations to allow for their survival in both the gut and salivary glands of the tsetse fly, as well as in the bloodstream of their mammalian host. Upon feeding on an infected host, the tsetse fly takes up slender, intermediate and stumpy bloodstream forms. In the fly midgut stumpy forms differentiate into non-infectious procyclic forms. Reacquisition of infectivity is achieved through a complex developmental program that culminates in the tsetse salivary glands with the generation of infectious metacyclics. Although the intricate nature of trypanosome development in the fly has been recognized for more than a century, the molecular mechanisms are still mysterious, due in part to the experimental challenges posed by the tsetse fly. We found that overexpression of the T. brucei RNA-binding protein RBP6 in cultured non-infectious procyclic forms initiates differentiation into the developmental stages found in tsetse flies and culminates with the generation of infective metacyclics expressing the variant surface glycoprotein (VSG) coat. Our first goal will be to delineate the mechanism of action of RBP6. As RBP6 appears to be a """"""""master regulator"""""""" triggering a cascade of events, it will be critical to identify the primary mRNA targets of RBP6. This will provide crucial information about gene products involved in the early stages of differentiation and for formulating a testable hypothesis about the cellular adaptations occurring in the transition from procyclic to epimastigotes forms. Our second goal will be to provide a transcriptomic and proteomic map of epimastigotes and metacyclics and to decode the biology of metacyclogenesis. Finally, the discovery of novel genes, besides VSG, required for metacyclic differentiation will be a major breakthrough toward deciphering how the process of acquisition of infectivity is brought about. Taken together our research plan provides unique opportunities to illuminate the differentiation program from procyclic to metacyclic and reveal the mode of action of an important RNA binding protein.

Public Health Relevance

Parasitic protozoa are a major cause of global infectious diseases and thus, represent one of the most serious threats to public health. Among these are African trypanosomes, the causative agents of African trypanosomiasis or sleeping sickness in humans and a wasting and fatal disease (Nagana) in cattle, domestic pigs and other farm animals causing a profound effect on the economy of much of the continent. Our proposed studies will provide an insight into the developmental program that leads to the establishment of infectious trypanosomes, which has the potential to expose new strategies to combat the diseases caused by these deadly parasites.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Special Emphasis Panel (ZRG1-IDM-M (02))
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Mcgugan, Glen C
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Yale University
Public Health & Prev Medicine
Schools of Medicine
New Haven
United States
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Shi, Huafang; Butler, Kiantra; Tschudi, Christian (2018) A single-point mutation in the RNA-binding protein 6 generates Trypanosoma brucei metacyclics that are able to progress to bloodstream forms in vitro. Mol Biochem Parasitol 224:50-56
Kolev, Nikolay G; Ramsdell, Trisha K; Tschudi, Christian (2018) Temperature shift activates bloodstream VSG expression site promoters in Trypanosoma brucei. Mol Biochem Parasitol 226:20-23
Shi, Huafang; Butler, Kiantra; Tschudi, Christian (2018) Differential expression analysis of transcriptome data of Trypanosoma brucei RBP6 induction in procyclics leading to infectious metacyclics and bloodstream forms in vitro. Data Brief 20:978-980
Srivastava, Ankita; Badjatia, Nitika; Lee, Ju Huck et al. (2018) An RNA polymerase II-associated TFIIF-like complex is indispensable for SL RNA gene transcription in Trypanosoma brucei. Nucleic Acids Res 46:1695-1709
Damasceno, Jeziel D; Silva, Gabriel LA; Tschudi, Christian et al. (2017) Evidence for regulated expression of Telomeric Repeat-containing RNAs (TERRA) in parasitic trypanosomatids. Mem Inst Oswaldo Cruz 112:572-576
Kolev, Nikolay G; G├╝nzl, Arthur; Tschudi, Christian (2017) Metacyclic VSG expression site promoters are recognized by the same general transcription factor that is required for RNA polymerase I transcription of bloodstream expression sites. Mol Biochem Parasitol 216:52-55
Christiano, Romain; Kolev, Nikolay G; Shi, Huafang et al. (2017) The proteome and transcriptome of the infectious metacyclic form of Trypanosoma brucei define quiescent cells primed for mammalian invasion. Mol Microbiol 106:74-92
Savage, Amy F; Kolev, Nikolay G; Franklin, Joseph B et al. (2016) Transcriptome Profiling of Trypanosoma brucei Development in the Tsetse Fly Vector Glossina morsitans. PLoS One 11:e0168877
Ramey-Butler, Kiantra; Ullu, Elisabetta; Kolev, Nikolay G et al. (2015) Synchronous expression of individual metacyclic variant surface glycoprotein genes in Trypanosoma brucei. Mol Biochem Parasitol 200:1-4