@phdthesis{Zimmermann2020, author = {Zimmermann, Henriette}, title = {Antigenic variation and stumpy development in \(Trypanosoma\) \(brucei\)}, doi = {10.25972/OPUS-14690}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-146902}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2020}, abstract = {The eukaryotic parasite Trypanosoma brucei has evolved sophisticated strategies to persist within its mammalian host. Trypanosomes evade the hosts' immune system by antigenic variation of their surface coat, consisting of variant surface glycoproteins (VSGs). Out of a repertoire of thousands of VSG genes, only one is expressed at any given time from one of the 15 telomeric expression sites (ES). The VSG is stochastically exchanged either by a transcriptional switch of the active ES (in situ switch) or by a recombinational exchange of the VSG within the active ES. However, for infections to persist, the parasite burden has to be limited. The slender (sl) bloodstream form secretes the stumpy induction factor (SIF), which accumulates with rising parasitemia. SIF induces the irreversible developmental transition from the proliferative sl to the cell cycle-arrested but fly-infective stumpy (st) stage once a concentration threshold is reached. Thus, antigenic variation and st development ensure persistent infections and transmissibility. A previous study in monomorphic cells indicated that the attenuation of the active ES could be relevant for the development of trypanosomes. The present thesis investigated this hypothesis using the inducible overexpression of an ectopic VSG in pleomorphic trypanosomes, which possess full developmental competence. These studies revealed a surprising phenotypic plasticity: while the endogenous VSG was always down-regulated upon induction, the ESactivity determined whether the VSG overexpressors arrested in growth or kept proliferating. Full ES-attenuation induced the differentiation of bona fide st parasites independent of the cell density and thus represents the sole natural SIF-independent differentiation trigger to date. A milder decrease of the ES-activity did not induce phenotypic changes, but appeared to prime the parasites for SIF-induced differentiation. These results demonstrate that antigenic variation and development are linked and indicated that the ES and the VSG are independently regulated. Therefore, I investigated in the second part of my thesis how ES-attenuation and VSG-silencing can be mediated. Integration of reporters with a functional or defective VSG 3'UTR into different genomic loci showed that the maintenance of the active state of the ES depends on a conserved motif within the VSG 3'UTR. In situ switching was only triggered when the telomere-proximal motif was partially deleted, suggesting that it serves as a DNA-binding motif for a telomere-associated protein. The VSG levels seem to be additionally regulated in trans based on the VSG 3'UTR independent of the genomic context, which was reinforced by the regulation of a constitutively expressed reporter with VSG 3' UTR upon ectopic VSG overexpression.}, subject = {Trypanosoma brucei}, language = {en} } @article{SchusterLisackSubotaetal.2021, author = {Schuster, Sarah and Lisack, Jaime and Subota, Ines and Zimmermann, Henriette and Reuter, Christian and Mueller, Tobias and Morriswood, Brooke and Engstler, Markus}, title = {Unexpected plasiticty in the life cycle of Trypanosoma brucei}, series = {eLife}, volume = {10}, journal = {eLife}, doi = {10.7554/eLife.66028.sa2}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-261744}, year = {2021}, abstract = {African trypanosomes cause sleeping sickness in humans and nagana in cattle. These unicellular parasites are transmitted by the bloodsucking tsetse fly. In the mammalian host's circulation, proliferating slender stage cells differentiate into cell cycle-arrested stumpy stage cells when they reach high population densities. This stage transition is thought to fulfil two main functions: first, it auto-regulates the parasite load in the host; second, the stumpy stage is regarded as the only stage capable of successful vector transmission. Here, we show that proliferating slender stage trypanosomes express the mRNA and protein of a known stumpy stage marker, complete the complex life cycle in the fly as successfully as the stumpy stage, and require only a single parasite for productive infection. These findings suggest a reassessment of the traditional view of the trypanosome life cycle. They may also provide a solution to a long-lasting paradox, namely the successful transmission of parasites in chronic infections, despite low parasitemia.}, language = {en} } @article{ZimmermannSubotaBatrametal.2017, author = {Zimmermann, Henriette and Subota, Ines and Batram, Christopher and Kramer, Susanne and Janzen, Christian J. and Jones, Nicola G. and Engstler, Markus}, title = {A quorum sensing-independent path to stumpy development in Trypanosoma brucei}, series = {PLoS Pathogens}, volume = {13}, journal = {PLoS Pathogens}, number = {4}, doi = {10.1371/journal.ppat.1006324}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-158230}, pages = {e1006324}, year = {2017}, abstract = {For persistent infections of the mammalian host, African trypanosomes limit their population size by quorum sensing of the parasite-excreted stumpy induction factor (SIF), which induces development to the tsetse-infective stumpy stage. We found that besides this cell density-dependent mechanism, there exists a second path to the stumpy stage that is linked to antigenic variation, the main instrument of parasite virulence. The expression of a second variant surface glycoprotein (VSG) leads to transcriptional attenuation of the VSG expression site (ES) and immediate development to tsetse fly infective stumpy parasites. This path is independent of SIF and solely controlled by the transcriptional status of the ES. In pleomorphic trypanosomes varying degrees of ES-attenuation result in phenotypic plasticity. While full ES-attenuation causes irreversible stumpy development, milder attenuation may open a time window for rescuing an unsuccessful antigenic switch, a scenario that so far has not been considered as important for parasite survival.}, language = {en} } @article{ElHelouBiegnerBodeetal.2019, author = {El-Helou, Sabine M. and Biegner, Anika-Kerstin and Bode, Sebastian and Ehl, Stephan R. and Heeg, Maximilian and Maccari, Maria E. and Ritterbusch, Henrike and Speckmann, Carsten and Rusch, Stephan and Scheible, Raphael and Warnatz, Klaus and Atschekzei, Faranaz and Beider, Renata and Ernst, Diana and Gerschmann, Stev and Jablonka, Alexandra and Mielke, Gudrun and Schmidt, Reinhold E. and Sch{\"u}rmann, Gesine and Sogkas, Georgios and Baumann, Ulrich H. and Klemann, Christian and Viemann, Dorothee and Bernuth, Horst von and Kr{\"u}ger, Renate and Hanitsch, Leif G. and Scheibenbogen, Carmen M. and Wittke, Kirsten and Albert, Michael H. and Eichinger, Anna and Hauck, Fabian and Klein, Christoph and Rack-Hoch, Anita and Sollinger, Franz M. and Avila, Anne and Borte, Michael and Borte, Stephan and Fasshauer, Maria and Hauenherm, Anja and Kellner, Nils and M{\"u}ller, Anna H. and {\"U}lzen, Anett and Bader, Peter and Bakhtiar, Shahrzad and Lee, Jae-Yun and Heß, Ursula and Schubert, Ralf and W{\"o}lke, Sandra and Zielen, Stefan and Ghosh, Sujal and Laws, Hans-Juergen and Neubert, Jennifer and Oommen, Prasad T. and H{\"o}nig, Manfred and Schulz, Ansgar and Steinmann, Sandra and Klaus, Schwarz and D{\"u}ckers, Gregor and Lamers, Beate and Langemeyer, Vanessa and Niehues, Tim and Shai, Sonu and Graf, Dagmar and M{\"u}glich, Carmen and Schmalzing, Marc T. and Schwaneck, Eva C. and Tony, Hans-Peter and Dirks, Johannes and Haase, Gabriele and Liese, Johannes G. and Morbach, Henner and Foell, Dirk and Hellige, Antje and Wittkowski, Helmut and Masjosthusmann, Katja and Mohr, Michael and Geberzahn, Linda and Hedrich, Christian M. and M{\"u}ller, Christiane and R{\"o}sen-Wolff, Angela and Roesler, Joachim and Zimmermann, Antje and Behrends, Uta and Rieber, Nikolaus and Schauer, Uwe and Handgretinger, Rupert and Holzer, Ursula and Henes, J{\"o}rg and Kanz, Lothar and Boesecke, Christoph and Rockstroh, J{\"u}rgen K. and Schwarze-Zander, Carolynne and Wasmuth, Jan-Christian and Dilloo, Dagmar and H{\"u}lsmann, Brigitte and Sch{\"o}nberger, Stefan and Schreiber, Stefan and Zeuner, Rainald and Ankermann, Tobias and Bismarck, Philipp von and Huppertz, Hans-Iko and Kaiser-Labusch, Petra and Greil, Johann and Jakoby, Donate and Kulozik, Andreas E. and Metzler, Markus and Naumann-Bartsch, Nora and Sobik, Bettina and Graf, Norbert and Heine, Sabine and Kobbe, Robin and Lehmberg, Kai and M{\"u}ller, Ingo and Herrmann, Friedrich and Horneff, Gerd and Klein, Ariane and Peitz, Joachim and Schmidt, Nadine and Bielack, Stefan and Groß-Wieltsch, Ute and Classen, Carl F. and Klasen, Jessica and Deutz, Peter and Kamitz, Dirk and Lassy, Lisa and Tenbrock, Klaus and Wagner, Norbert and Bernbeck, Benedikt and Brummel, Bastian and Lara-Villacanas, Eusebia and M{\"u}nstermann, Esther and Schneider, Dominik T. and Tietsch, Nadine and Westkemper, Marco and Weiß, Michael and Kramm, Christof and K{\"u}hnle, Ingrid and Kullmann, Silke and Girschick, Hermann and Specker, Christof and Vinnemeier-Laubenthal, Elisabeth and Haenicke, Henriette and Schulz, Claudia and Schweigerer, Lothar and M{\"u}ller, Thomas G. and Stiefel, Martina and Belohradsky, Bernd H. and Soetedjo, Veronika and Kindle, Gerhard and Grimbacher, Bodo}, title = {The German national registry of primary immunodeficiencies (2012-2017)}, series = {Frontiers in Immunology}, volume = {10}, journal = {Frontiers in Immunology}, doi = {10.3389/fimmu.2019.01272}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-226629}, year = {2019}, abstract = {Introduction: The German PID-NET registry was founded in 2009, serving as the first national registry of patients with primary immunodeficiencies (PID) in Germany. It is part of the European Society for Immunodeficiencies (ESID) registry. The primary purpose of the registry is to gather data on the epidemiology, diagnostic delay, diagnosis, and treatment of PIDs. Methods: Clinical and laboratory data was collected from 2,453 patients from 36 German PID centres in an online registry. Data was analysed with the software Stata® and Excel. Results: The minimum prevalence of PID in Germany is 2.72 per 100,000 inhabitants. Among patients aged 1-25, there was a clear predominance of males. The median age of living patients ranged between 7 and 40 years, depending on the respective PID. Predominantly antibody disorders were the most prevalent group with 57\% of all 2,453 PID patients (including 728 CVID patients). A gene defect was identified in 36\% of patients. Familial cases were observed in 21\% of patients. The age of onset for presenting symptoms ranged from birth to late adulthood (range 0-88 years). Presenting symptoms comprised infections (74\%) and immune dysregulation (22\%). Ninety-three patients were diagnosed without prior clinical symptoms. Regarding the general and clinical diagnostic delay, no PID had undergone a slight decrease within the last decade. However, both, SCID and hyper IgE-syndrome showed a substantial improvement in shortening the time between onset of symptoms and genetic diagnosis. Regarding treatment, 49\% of all patients received immunoglobulin G (IgG) substitution (70\%-subcutaneous; 29\%-intravenous; 1\%-unknown). Three-hundred patients underwent at least one hematopoietic stem cell transplantation (HSCT). Five patients had gene therapy. Conclusion: The German PID-NET registry is a precious tool for physicians, researchers, the pharmaceutical industry, politicians, and ultimately the patients, for whom the outcomes will eventually lead to a more timely diagnosis and better treatment.}, language = {en} }