publications Archives - Center for Tropical and Emerging Global Diseases

The importance of persistence and dormancy in Trypanosoma cruzi infection and Chagas disease

Donna Huber on June 5, 2025

Dormant and metabolically active T. cruzi amastigotes.

Trypanosoma cruzi typically establishes a life-long infection in its mammalian hosts, causing the destruction of muscle tissues and ultimately resulting in potentially fatal Chagas disease. In this review, we consider the array of avoidance mechanisms that allow for T. cruzi persistence, many of which are unconventional among protozoan pathogens but which collectively are highly effective in the face of otherwise potent host immune responses. We also reflect on the phenomenon of dormancy in T. cruzi amastigotes, which is likely not involved in the long-term persistence of infection. Lastly, we consider how these phenomena of persistence and dormancy complicate the effectiveness of potential therapeutic interventions to prevent Chagas disease.

Molly E Bunkofske, Fernando J Sanchez-Valdez, Rick L Tarleton. Curr Opin Microbiol. 2025 Jun 5:86:102615. doi: 10.1016/j.mib.2025.102615.

Chemical and Genetic Validation of an Essential Calcium Entry Channel of Trypanosoma brucei as a Therapeutic Target

Donna Huber on June 3, 2025

The Trypanosoma brucei group of parasites causes Nagana in cattle and human African trypanosomiasis, or sleeping sickness, in humans. Current drugs against these parasites have severe toxicity, vaccines are not available, and development of drug resistance makes finding new chemotherapeutic targets imperative. Ion channels, which are involved in several biological processes, are targets of many therapeutically useful agents, and they remain significantly underexplored as therapeutic targets in parasites. Here, we report the presence of a voltage gated Ca²⁺ channel (VGCC, TbCa_v), which is localized in the flagellar plasma membrane (PM) of T. brucei and is essential for proliferation of both bloodstream (BSF) and procyclic forms (PCF) of the parasite. TbCa_V is a single subunit channel capable of transporting Ca²⁺ when expressed in mutant yeast lacking PM Ca²⁺ channels or in HEK293T cells. Through the virtual screening of a commercial chemical library using dynamic ensembles of various conformations of TbCa_v and associated docking analyses, several inhibitors of TbCa_v were discovered. As pharmacological validation of the essential roles of TbCa_v, these compounds were shown to inhibit T. brucei growth with the most potent agent, N-(7-nitro-2,1,3-benzoxadiazol-4-yl) acetamide (NBD-A), exhibiting an EC₅₀ of 25 ± 3 nM and no cytotoxicity in Vero cells possessing related channels. Thus, such studies constitute pharmacological validation of TbCa_v as a viable therapeutic target of T. brucei.

Guozhong Huang, Harmanpreet Singh, Priti Singh, Rohit Kumar Varshnaya, Donald Hamelberg, Binghe Wang, Roberto Docampo. ACS Infect Dis. 2025 Jun 3. doi: 10.1021/acsinfecdis.5c00329.

HaloPROTAC3 does not trigger the degradation of the halotagged parasitophorous vacuole membrane protein UIS4 during Plasmodium liver stage development

Donna Huber on May 26, 2025

FIgure 1 Host-driven targeted degradation of a Plasmodium liver stage PVM protein using HaloTag technology. — Host-driven targeted degradation of a Plasmodium liver stage PVM protein using HaloTag technology.

Targeted protein degradation (TPD) is a novel strategy for developing therapeutics against pathogens. Prior to causing malaria, Plasmodium parasites replicate within hepatocytes as liver stages, surrounded by a parasitophorous vacuole membrane (PVM). We hypothesized that TPD can be employed to trigger host-driven degradation of essential liver stage PVM proteins and lead to parasite death. To explore this, we took advantage of the proteolysis-targeting-chimera HaloPROTAC3, a molecule that recruits the host von Hippel-Lindau (VHL) E3 ligase to the HaloTag (HT). Parasites expressing HT fused to the host cytosol-exposed domain of the PVM protein UIS4 (UIS4-HT) were generated in Plasmodium berghei and Plasmodium cynomolgi, but only P. berghei UIS4-HT enabled productive liver stage infection experiments in vitro. Although HaloPROTAC3 triggered the degradation of HT proteins in host cells, it had no impact on the survival of P. berghei UIS4-HT liver stages. Furthermore, HaloPROTAC3 bound to P. berghei UIS4-HT but did not recruit VHL or trigger ubiquitination of the PVM. Overall, although this study did not establish whether host-driven TPD can degrade Plasmodium PVM proteins, it highlights the challenges of developing TPD approaches against novel targets and offers insights for advancing this therapeutic strategy against pathogens.

Melanie Lam, Alexandra Probst, Laura Torres, Ashley A Lantigua, Matthew E Fishbaugher, Jyothsna R Kumar, Manuel Saldivia, Allison Torres, Shreeya Hegde, Maya Aleshnick, Charlie Jennison, Sarah G H Roberson, Chester J Joyner, Ashley M Vaughan, Brandon K Wilder, Carole Manneville, Erika L Flannery, David Marcellin, Beat Nyfeler, Zacharias Thiel, Sebastian A Mikolajczak, Anke Harupa, Gabriel Mitchell. Sci Rep. 2025 May 26;15(1):18323. doi: 10.1038/s41598-025-98257-9.

Protocol for detecting peptide hormones in mosquito tissues

Donna Huber on May 24, 2025

Peptide hormones in insects are primarily expressed in specialized brain, ventral nerve chord, and midgut cells. When released, peptide hormones play crucial roles in regulating physiology, reproduction, and behavior. Here, we present a protocol for detecting peptide hormones in mosquito tissues such as the brain, midgut, and hemolymph. We describe steps for tissue preparation, immunocytochemistry, fluorescent quantification, and enzyme-linked immunoassay (EIA). This protocol offers a versatile and effective approach for studying peptide hormone expression and abundance in insects. For complete details on the use and execution of this protocol, please refer to Dou et al.¹.

Xiaoyi Dou, Kangkang Chen, Mark R Brown, Michael R Strand. STAR Protoc. 2025 May 24;6(2):103850. doi: 10.1016/j.xpro.2025.103850.

A symbiotic gene stimulates aggressive behavior favoring the survival of parasitized caterpillars

Donna Huber on April 28, 2025

Animals often exhibit increased aggression in response to starvation, while parasites often manipulate host behavior. In contrast, underlying molecular mechanisms for these behavioral changes are mostly unknown. The diamondback moth, Plutella xylostella, is an agricultural pest that feeds on cruciferous plants as larvae, while Cotesia vestalis is a parasitoid wasp that parasitizes diamondback moth larvae. In this study, we determined that unparasitized diamondback moth larvae exhibit increased aggression and cannibalism when starved, while starved larvae parasitized by C. vestalis were more aggressive than unparasitized larvae. C. vestalis harbors a domesticated endogenized virus named Cotesia vestalis bracovirus (CvBV) that wasps inject into parasitized hosts. Starvation increased octopamine (OA) levels in the central nervous system (CNS) of diamondback moth larvae while a series of experiments identified a CvBV-encoded gene product named Assailant that further increased aggression in starved diamondback moth larvae. We determined that Assailant increases OA levels by activating tyramine beta-hydroxylase (PxTβh), which is a key enzyme in the OA biosynthesis pathway. Ectopic expression of assailant in Drosophila melanogaster likewise upregulated expression of DmTβh and OA, which increased aggressive behavior in male flies as measured by a well-established assay. While parasitized hosts are often thought to be at a competitive disadvantage to nonparasitized individuals, our results uncover how a parasitoid uses an endogenized virus to increase host aggression and enhance survival of offspring when competing against unparasitized hosts.

Zhiwei Wu, Xiaotong Wu, Zhizhi Wang, Xiqian Ye, Lan Pang, Yanping Wang, Yuenan Zhou, Ting Chen, Sicong Zhou, Zehua Wang, Yifeng Sheng, Qichao Zhang, Jiani Chen, Pu Tang, Xingxing Shen, Jianhua Huang, Jean-Michel Drezen, Michael R Strand, Xuexin Chen. Proc Natl Acad Sci U S A. 2025 May 6;122(18):e2422935122. doi: 10.1073/pnas.2422935122.

Regulatory T cell memory: implications for malaria

Donna Huber on April 23, 2025

Figure 1.Hypothetical model of memory Treg development. Activated Tregs, which proliferate in the acute phase of malaria, leave a memory Treg pool in mice and humans.

Regulatory T cells (Tregs) can persist as memory cells (mTregs) in both infectious and non-infectious settings. However, their functional behavior, phenotypic stability, and suppressive properties upon antigen re-exposure remain poorly understood. Emerging evidence suggests that mTregs exhibit enhanced proliferation and suppressive capacity upon re-encountering the same antigen, a feature that may be critical in recurrent infections such as malaria. In malaria, Tregs are known to modulate immune responses and influence acute disease outcomes, suggesting that mTreg recall may play a significant role in long-term immunity. This review explores the biology of Treg memory, with a focus on malaria, and examines the immunological implications of maintaining a suppressive mTreg population in malaria immunity.

Nana Appiah Essel Charles-Chess, Samarchith P Kurup. J Immunol. 2025 Apr 23:vkaf067. doi: 10.1093/jimmun/vkaf067

Lysosome and plasma membrane Piezo channels of Trypanosoma cruzi are essential for proliferation, differentiation and infectivity

Donna Huber on April 23, 2025

Fig 1. Conditional knockout of TcPiezo1 and subcellular localization.

Trypanosoma cruzi, the causative agent of Chagas disease, is a parasitic protist that affects millions of people worldwide. Currently there are no fully effective drugs or vaccines available. Contact of T. cruzi infective forms with their host cells or with the extracellular matrix increases their intracellular Ca²⁺ concentration suggesting a mechano-transduction process. We report here that T. cruzi possesses two distinct mechanosensitive Piezo channels, named TcPiezo1 and TcPiezo2, with different subcellular localizations but similarly essential for normal proliferation, differentiation, and infectivity. While TcPiezo1 localizes to the plasma membrane, TcPiezo2 localizes to the lysosomes. Downregulation of TcPiezo1 expression by a novel ligand-regulated hammerhead ribozyme (HHR) significantly inhibited Ca²⁺ entry in cells expressing a genetically encoded Ca²⁺ indicator while downregulation of TcPiezo2 expression inhibited Ca²⁺ release from lysosomes, which are now identified as novel acidic Ca²⁺ stores in trypanosomes. The channels are activated by contact with extracellular matrix and by hypoosmotic stress. The results establish the essentiality of Piezo channels for the life cycle and Ca²⁺ homeostasis of T. cruzi and a novel lysosomal localization for a Piezo channel in eukaryotes.

Guozhong Huang, Mayara S Bertolini, Justin Wiedeman, Ronald D Etheridge, Teresa Cruz-Bustos, Roberto Docampo. PLoS Pathog. 2025 Apr 23;21(4):e1013105. doi: 10.1371/journal.ppat.1013105.

Serial ‘deep-sampling’ PCR of fragmented DNA reveals the wide range of Trypanosoma cruzi burden among chronically infected human, macaque, and canine hosts, and allows accurate monitoring of parasite load following treatment

Donna Huber on April 15, 2025

Figure 2 Monthly screening protocol for macaques. — Monthly screening protocol for macaques.

Infection with the protozoan parasite Trypanosoma cruzi is generally well-controlled by host immune responses, but appears to be rarely eliminated. The resulting persistent, low-level infection results in cumulative tissue damage with the greatest impact generally in the heart in the form of chagasic cardiomyopathy. The relative success in immune control of T. cruzi infection usually averts acute phase death but has the negative consequence that the low-level presence of T. cruzi in hosts is challenging to detect unequivocally. Thus, it is difficult to identify those who are actively infected and, as well, problematic to gauge the impact of treatment, particularly in the evaluation of the relative efficacy of new drugs. In this study, we employ DNA fragmentation and high numbers of replicate PCR reaction (‘deep-sampling’) and to extend the quantitative range of detecting T. cruzi in blood by at least three orders of magnitude relative to current protocols. When combined with sampling blood at multiple time points, deep sampling of fragmented DNA allowed for detection of T. cruzi in all infected hosts in multiple host species, including humans, macaques, and dogs. In addition, we provide evidence for a number of characteristics not previously rigorously quantified in the population of hosts with naturally acquired T. cruzi infection, including, a >6 log variation between chronically infected individuals in the stable parasite levels, a continuing decline in parasite load during the second and third years of infection in some hosts, and the potential for parasite load to change dramatically when health conditions change. Although requiring strict adherence to contamination-prevention protocols and significant resources, deep-sampling PCR provides an important new tool for assessing therapies and for addressing long-standing questions in T. cruzi infection and Chagas disease.

Brooke E White, Carolyn L Hodo, Sarah Hamer, Ashley B Saunders, Susana A Laucella, Daniel B Hall, Rick L Tarleton. Elife. 2025 Apr 15:14:RP104547. doi: 10.7554/eLife.104547.

Discovery and optimization of a novel carboxamide scaffold with selective antimalarial activity

Donna Huber on March 28, 2025

Artemisinin combination therapies (ACTs) are critical components of malaria control worldwide. Alarmingly, ACTs have begun to fail, owing to the rise in artemisinin resistance. Thus, there is an urgent need for an expanded set of novel antimalarials to generate new combination therapies. Herein, we have identified a 1,2,4-triazole-containing carboxamide scaffold that, through scaffold hopping efforts, resulted in a nanomolar potent deuterated picolinamide (110). The lead compound of this class (110) displays moderate aqueous solubility (13.4 μM) and metabolic stability (CLintapp HLM 17.3 μL/min/mg) in vitro, as well as moderate oral bioavailability (%F 16.2) in invivo pharmacokinetic studies. Compound 110 also displayed activity against various P. falciparum isolates with different genetic backgrounds and a slow-to-moderate rate of killing (average parasite reduction ratio 2.4), making the series appealing for further development.

Alicia Wagner, Roger Trombley, Maris Podgurski, Anthony A Ruberto, Meng Cui, Caitlin A Cooper, William E Long, Gia-Bao Nguyen, Adriana A Marin, Sarah Lee Mai, Franco Lombardo, Steven P Maher, Dennis E Kyle, Roman Manetsch.Eur J Med Chem. 2025 Mar 28:291:117572. doi: 10.1016/j.ejmech.2025.117572.

Type I interferons induce guanylate-binding proteins and lysosomal defense in hepatocytes to control malaria

Donna Huber on March 25, 2025

Plasmodium parasites undergo development and replication within hepatocytes before infecting erythrocytes and initiating clinical malaria. Although type I interferons (IFNs) are known to hinder Plasmodium infection within the liver, the underlying mechanisms remain unclear. Here, we describe two IFN-I-driven hepatocyte antimicrobial programs controlling liver-stage malaria. First, oxidative defense by NADPH oxidases 2 and 4 triggers a pathway of lysosomal fusion with the parasitophorous vacuole (PV) to help clear Plasmodium. Second, guanylate-binding protein (GBP) 1-mediated disruption of the PV activates the caspase-1 inflammasome, inducing pyroptosis to remove infected host cells. Remarkably, both human and mouse hepatocytes enlist these cell-autonomous immune programs to eliminate Plasmodium, with their pharmacologic or genetic inhibition leading to profound malarial susceptibility in vivo. In addition to identifying IFN-I-mediated cell-autonomous immune circuits controlling Plasmodium infection in the hepatocytes, our study also extends the understanding of how non-immune cells are integral to protective immunity against malaria.

Camila Marques-da-Silva, Clyde Schmidt-Silva, Carson Bowers, Nana Appiah Essel Charles-Chess, Cristina Samuel, Justine C Shiau, Eui-Soon Park, Zhongyu Yuan, Bae-Hoon Kim, Dennis E Kyle, John T Harty, John D MacMicking, Samarchith P Kurup. Cell Host Microbe. 2025 Mar 25:S1931-3128(25)00091-5. doi: 10.1016/j.chom.2025.03.008.

Category: publications