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Category: publications

Characterization of β-Carboline Derivatives Reveals a High Barrier to Resistance and Potent Activity against Ring-Stage and DHA-Induced Dormant Plasmodium falciparum

Donna Huber on October 17, 2025

graphical abstract

Malaria, caused by Plasmodium falciparum, remains a major global health challenge, with an estimated 263 million new infections and 597,000 deaths annually. Increasing resistance to current antimalarial drugs underscores the urgent need for new therapeutics that target novel pathways in the parasite. We previously reported a novel class of β-carboline antimalarials, exemplified by PRC1584, which demonstrated a favorable oral pharmacokinetic profile, in vivo efficacy in Plasmodium berghei-infected mice, and no cross-resistance with other antimalarials in various P. falciparum strains. In this study, we demonstrate that PRC1584 exhibits a high resistance barrier and retains potent activity against fresh Ugandan P. falciparum isolates. PRC1584, along with its more potent analog PRC1697, demonstrated strong in vitro potency against both actively proliferating ring stages and dihydroartemisinin-induced dormant stages. Additionally, our study demonstrated that PfKelch13-C580Y mutation was associated with an increased susceptibility to PRC1584, whereas PfKelch13-R549T and Pfcoronin-R100 K-E107V mutations were not associated with this effect. These findings underscore the therapeutic potential of this new “irresistible” compound class, support a possible novel mechanism of action, and suggest the future development of novel ACTs active against resistant parasites by targeting DHA dormancy, an essential survival mechanism of P. falciparum.

Reagan S Haney, Joshua H Butler, Lyric A Wardlaw, Emilio F Merino, Victoria Mendiola, Caitlin A Cooper, Jopaul Mathew, Patrick K Tumwebaze, Philip J Rosenthal, Roland A Cooper, Dennis E Kyle, Zaira Rizopoulos, Delphine Baud, Stephen Brand, Maxim Totrov, Paul R Carlier, Maria Belen Cassera. ACS Infect Dis. 2025 Oct 17. doi: 10.1021/acsinfecdis.5c00714.

Amplicon sequencing detects, identifies, and quantifies minority variants in mixed-species infections of Cryptosporidium parasites

Donna Huber on October 8, 2025

Fig 1 Cryptosporidium species identification using 18S amplicon sequencing.
Fig 1 Cryptosporidium species identification using 18S amplicon sequencing.

 

Cryptosporidium is a globally endemic parasite genus with over 40 recognized species. While C. hominis and C. parvum are responsible for most human infections, human cases involving other species have also been reported. Furthermore, there is increasing evidence of simultaneous infections with multiple species. Therefore, we devised a new means to identify various species of Cryptosporidium in mixed infections by sequencing a 431 bp amplicon of the 18S rRNA gene encompassing two variable regions. Using the DADA2 pipeline, amplicons were first identified to a genus using the SILVA 132 reference database; then Cryptosporidium amplicons to a species using a custom database. This approach demonstrated sensitivity, successfully detecting and accurately identifying as little as 0.001 ng of C. parvum DNA in a complex stool background. Notably, we differentiated mixed infections and demonstrated the ability to identify potentially novel species of Cryptosporidium both in situ and in vitro. Using this method, we identified Cryptosporidium parvum in Egyptian rabbits with three samples showing minor mixed infections. By contrast, no mixed infections were detected in Egyptian children, who were primarily infected with C. hominis. Thus, this pipeline provides a sensitive tool for Cryptosporidium species-level identification, allowing for the detection and accurate identification of minor variants and mixed infections.

IMPORTANCE Cryptosporidium is a eukaryotic parasite and a leading global cause of waterborne diarrhea, with over 40 recognized species infecting livestock, wildlife, and people. While we have effective tools for detecting Cryptosporidium in clinical and agricultural water samples, there is still a need for a method that can efficiently identify known species as well as infections with multiple Cryptosporidium species, which are increasingly being reported. In this study, we utilized sequencing of a specific region to develop a sensitive and accurate identification workflow for Cryptosporidium species based on high-throughput sequencing. This method can distinguish between all 40 recognized species and accurately detect mixed infections. Our approach provides a sensitive and reliable means to identify Cryptosporidium species in complex clinical and agricultural samples. This has important implications for clinical diagnostics, biosurveillance, and understanding disease transmission, ultimately benefiting clinicians and produce growers.

Randi Turner, Doaa Naguib, Elora Pierce, Alison Li, Matthew Valente, Travis C Glenn, Benjamin M Rosenthal, Jessica C Kissinger, Asis Khan. mBio. 2025 Oct 8;16(10):e0110925. doi: 10.1128/mbio.01109-25.

Large DNA Viruses That Parasitoid Wasps Transmit to Hosts

Donna Huber on October 7, 2025

Many types of viruses have been identified in parasitoid wasps and other Hymenoptera. Parasitoid wasps also transmit several viruses to hosts through the piercing ovipositors that females use to lay eggs. Most viruses that are known to be transmitted by parasitoids have large double-stranded DNA genomes. We summarize the range of interactions that have evolved between parasitoid wasps and the viruses they transmit. Some viruses are mechanically transmitted to hosts, which can reduce the fitness of wasp offspring. Others have evolved into beneficial symbionts or reproductive parasites that replicate in wasps and hosts. Some large dsDNA viruses have also been co-opted into domesticated endogenized viruses that are vertically transmitted to offspring but still produce virions or virus-like particles that wasps use to parasitize hosts. We conclude by discussing future directions and why parasitoid wasps likely transmit many more viruses than are currently known.

Michael R Strand, Kelsey A Coffman, Gaelen R Burke. Annu Rev Entomol. 2025 Oct 7. doi: 10.1146/annurev-ento-121423-013425.

Signals from the head and germinative region differentially regulate regeneration competence of the tapeworm Hymenolepis diminuta

Donna Huber on October 7, 2025

The germinative region regenerates after amputation.

Competence to regenerate lost tissues varies widely across species. The rat tapeworm, Hymenolepis diminuta, undergoes continual cycles of shedding and regenerating thousands of reproductive segments to propagate the species. Despite its prowess, H. diminuta can only regenerate posteriorly from a singular tissue: the neck or germinative region (GR). What cells and signaling pathways restrict regeneration competence to the GR? In this study, we show that the head regulates regeneration competence by promoting maintenance of the GR and inhibiting proglottid formation in a distance-dependent manner. Anterior-posterior (A-P) patterning within the GR provide local signals that contribute to these responses. βcat1 is necessary for stem cell maintenance, proliferation and proglottidization. On the other hand, sfrp is necessary for maintaining the GR at its proper length. Our study demonstrates that the head organizes a balance of pro- and anti-regeneration signals that must be integrated together and therefore control competence to regenerate.

Elise McCollough Nanista, Landon Elizabeth Poythress, Isabell Reese Skipper, Trevor Haskins, Marieher Felix Cora, Tania Rozario. Development. 2025 Oct 7:dev.204781. doi: 10.1242/dev.204781.

Insulin-like peptides activate egg formation in the Asian malaria mosquito Anopheles stephensi

Donna Huber on October 7, 2025

graphical abstract

Background: The mosquito family Culicidae diverged into the subfamilies Anophelinae and Culicinae approximately 179 million years ago. Most female mosquitoes are anautogenous and must blood-feed on a vertebrate to produce eggs. Regulation of egg-producing gonotrophic cycles is best understood in the culicine Aedes aegypti. Anopheline mosquitoes encode all of the hormones that regulate gonotrophic cycles in Ae. aegypti, but the processes regulating egg formation may not be fully similar. In this study, we conducted experiments that compared egg formation in Anopheles stephensi to prior findings reported for Ae. aegypti.

Methods: Assays for yolk deposition into oocytes, ovary ecdysteroidogenesis, vitellogenin expression, nutrient storage and oviposition were used to characterize gonotrophic cycles in An. stephensi females that were mated or unmated.

Results: Yolk deposition into oocytes depended on the release of hormones produced in the head. Two insulin-like peptides, An. stephensi insulin-like peptide hormone 3 (AsILP3) and AsILP4, stimulated the vitellogenic phase in An. stephensi, as measured by several different assays, whereas ovary ecdysteroidogenic hormone (OEH) showed no stimulatory activity. Nutrient stores were lower in An. stephensi than Ae. aegypti, which was associated with females also being unresponsive to AsILP3 stimulation in the absence of a blood meal. Anopheles stephensi males transferred ecdysteroids (ECDs) to females, which was associated with mated females producing and laying more eggs than unmated females. However, mated and unmated females did not show differences in ECD production by the ovaries or vitellogenin expression at the messenger RNA level by the fat body. Most females that mated before consuming a first blood meal oviposited while most unmated females did not. Mating after consuming a first blood meal did not rescue oviposition. However, females that reabsorbed eggs and consumed a second blood meal did oviposit.

Conclusions: Regulation of gonotrophic cycles in An. stephensi shares some features with Ae. aegypti but also exhibits differences.

Benjamin L Phipps, Mark R Brown, Michael R Strand. Parasit Vectors. 2025 Oct 7;18(1):399. doi: 10.1186/s13071-025-07036-y.

Ghosts of symbionts past: The hidden history of the dynamic association between filarial nematodes and their Wolbachia endosymbionts

Donna Huber on October 1, 2025

graphical abstract

Many, but not all, parasitic filarial nematodes (Onchocercidae) carry intracellular, maternally-transmitted, alphaproteobacterial Wolbachia symbionts. The association between filarial nematodes and Wolbachia is often portrayed as mutualist, where the nematode is reliant on Wolbachia for an essential but unknown service. Wolbachia are targets for anti-filarial chemotherapeutic interventions for human disease. Wolbachia of Onchocercidae derive from four of the major supergroups (C, D, F and J) defined within the genus. We explored the evolutionary history of the filarial nematode-Wolbachia symbiosis in twenty-two nematode species, sixteen of which have current Wolbachia infections, by screening the nematode nuclear genome sequences for nuclear Wolbachia transfers, fragments of the Wolbachia genome that have been inserted into the nuclear genome. We identified Wolbachia insertions in five of the six species that have no current Wolbachia infection, showing they have previously had and have now lost Wolbachia infections. In currently-infected species we found a diversity of origins of the insertions, including many cases where they derived from a different supergroup to the current live infection. Mapping the origins of the insertions onto the filarial nematode phylogeny we derive a complex model of evolution of Wolbachia symbiosis. The history of association between Wolbachia and onchocercid nematodes includes not only cospeciation, as would be expected from a mutualist symbiosis, but also loss (in the five Wolbachia-free species), frequent symbiont replacement, and dual infection. This dynamic pattern is challenging to models that assume host-symbiont mutualism.

Emmelien Vancaester, Guy R Oldrieve, Alex Reid, Georgios Koutsovoulos, Dominik R Laetsch, Benjamin L Makepeace, Vincent Tanya, Sven Poppert, Jürgen Krücken, Adrian Wolstenholme, Mark Blaxter. G3 (Bethesda). 2025 Oct 1:jkaf226. doi: 10.1093/g3journal/jkaf226.

Pharmacokinetic Analysis of Sustained-Release Buprenorphine Formulations in Owl Monkeys (Aotus spp.)

Donna Huber on September 24, 2025

Buprenorphine is an opioid used for pain management in veterinary medicine but which requires frequent dosing to maintain therapeutic levels. Sustained-release buprenorphine (BSR) formulations can overcome this limitation, but genera- or species-specific studies that determine the time profiles of buprenorphine after dosing are sparse for NHPs. The objective of this study was to determine the plasma buprenorphine concentrations for 72 hours after a single subcutaneous administration of 0.2 mg/kg BSR or Ethiqa XR (EXR), an FDA-indexed, extended-release buprenorphine formulation, in owl monkeys. Blood samples were taken before and at 1, 4, 8, 24, 48, and 72 hours after administering either formulation to determine plasma buprenorphine concentrations. Clinical observations were also performed. A single 0.2 mg/kg dose of BSR and EXR raised plasma buprenorphine concentrations above the hypothesized therapeutic threshold for NHPs of 0.1 ng/mL within 1 hour of administration and maintained these levels for at least 72 hours. However, this dose did not sustain buprenorphine concentrations above the human efficacy threshold of 0.5 ng/mL for 72 hours. A subsequent study evaluated a single dose of 0.3 mg/kg EXR to determine whether this dose sustained plasma buprenorphine levels >0.5 ng/mL for 72 hours. Most owl monkeys reached this threshold and maintained plasma buprenorphine concentrations >0.5 ng/mL with this dose, albeit with increased side effects, including sedation and ptyalism. Injection site reactions were not observed in any animals during any study. In sum, this work indicates that a single subcutaneous dose of 0.2 mg/kg BSR or EXR can maintain buprenorphine above the hypothesized therapeutic threshold for NHPs of 0.1 ng/mL for 72 hours, but the EXR dose must be increased to reach the human efficacy threshold for 72 hours in owl monkeys.

Taylor A Sheridan, Celia L Saney, Amadis Vivas, Magdalena A Argomaniz, Wayne T Cheng, Tia S Freeman, David J Anderson, Saniya S Sabnis, Sarah Gayle Roberson, Cheryl Paladino, Matthew Doster, Anna Santos, Christopher A Reilly, Joseph E Rower, Gina A Kim, Mary Ann McCrackin, Chester J Joyner. J Am Assoc Lab Anim Sci. 2025 Sep 1:1-7. doi: 10.30802/AALAS-JAALAS-25-059.

Recent insights in the development and functions of insect hemocytes

Donna Huber on September 15, 2025

Figure 1. Cellular defense responses, humoral effector molecules and regulators of hemocyte functions in insects. In the center of the figure is a stylized image of an insect hemocyte. The arrow to the left points to the four major cellular defenses that are mediated by hemocytes. The arrow to the right points to five of the most important humoral effector molecules hemocytes produce. The upper arrow points to key receptors with functions in regulating hemocyte-mediated cellular defenses, while the lower arrow points to cytokines that regulate hemocyte functions or communication between hemocytes and other tissues. Small case statements below some headings provide brief explanations of terms while additional details are presented in the main text.
Figure 1. Cellular defense responses, humoral effector molecules and regulators of hemocyte functions in insects.

Hemocytes mediate defense responses that are collectively referred to as cellular immunity. Here I highlight recent progress in the study of hemocyte ontogeny and function. Studies conducted primarily in D. melanogaster, mosquitoes and Lepidoptera identify a number of transcription factors and signaling pathways that regulate hemocyte differentiation and proliferation. Recent single cell RNA sequencing studies identify genes that distinguish transitional states in different hemocyte populations and changes that occur during immune responses. Several new studies expand understanding of the functions of sessile hemocytes. Recent results also enhance understanding of the signaling pathways that regulate hemocyte functions.

Michael R Strand. Curr Opin Insect Sci. 2025 Sep 15:101434. doi: 10.1016/j.cois.2025.101434.

O-fucosylation affects abundance but not localization of select nucleocytoplasmic proteins in Toxoplasma gondii

Donna Huber on September 1, 2025

Figure one from the paper
Analysis of epitope-tagged GPN1 in cells. A) Schematic of GPN1 protein indicating conserved domains.

 

Toxoplasma gondii is a highly successful intracellular mammalian and avian pathogen that must adapt to a wide range of intracellular and extracellular environments. A mechanism that may support this is the modification of hydroxyamino acid rich sequences of nucleocytoplasmic proteins with O-fucose. O-fucosylation of possibly hundreds of proteins is mediated by a single highly conserved nucleocytoplasmic enzyme. Deletion of the SPY O-fucosyltransferase gene is tolerated but inhibits parasite proliferation in fibroblasts and their accumulation in mouse brains. A prior ectopic expression study suggested that O-fucose is required to detect proteins considered essential. To distinguish whether the SPY requirement was specific to the method or for protein expression per se, GPN1, an RNA polymerase chaperone, was epitope-tagged at its endogenous locus in both normal and SPYΔ strains. GPN1 was shown to be substantially and quantitatively O-fucosylated and exhibited a modest 24% reduction in level in SPYΔ cells. Proteomic analysis of its interactome indicated that fucosylation did not affect its association with RNA polymerase subunits. GPN1 was mostly cytoplasmic based on super-resolution immunofluorescence microscopy, and this localization was not affected by O-Fuc. A fusion of its O-fucosylated serine-rich domain to yellow fluorescent protein behaved similarly. In comparison, the abundance of a Zn-finger containing protein also depended on SPY, whereas the abundance and localization of ERK7 were not affected nor were levels of two other proteins. Thus O-fucose directly but modestly promotes the accumulation of select targets, but it does not enforce their localization in nuclear assemblies that are highlighted by immunofluorescence studies.

Megna Tiwari, Elisabet Gas-Pascual, Janice Teal-Urquides, John Samuelson, Christopher M West. Glycobiology. 2025 Sep 1:cwaf051. doi: 10.1093/glycob/cwaf051.

Use of the Slow-Delivery Platform, VacSIM, Shapes the Host Immune Response to Increase Protection Against Influenza Infection

Donna Huber on August 30, 2025

Antigen-specific serum antibody titers of immunized mice at Days −1, 27, and 55.

Influenza virus is a leading cause of global morbidity and mortality due to acute lower respiratory infection, even with the widespread use of multiple licensed influenza vaccines. However, antigenic drift during influenza replication can cause vaccine-induced antibodies to poorly neutralize influenza virus, thereby reducing vaccine effectiveness. To help overcome this problem, we leveraged a hydrogel platform with influenza hemagglutinin (HA) protein to induce prolonged antigen exposure. The hydrogel platform, Vaccine Self-Assembling Immune Matrix (VacSIM®), in combination with recombinant influenza H1 or H3 HA protein antigens, increased antigen-specific antibody titers in vaccinated mice, which led to decreased disease severity after H1N1 infection for H1 HA-vaccinated mice and decreased lung viral titers after H3N2 challenge for H3 HA-vaccinated mice. Sera collected from mice immunized with VacSIM and HA also showed broader HAI activity, increasing by 1–3 log against a panel of influenza viruses. These results were consistent with the use of cocktail immunization, containing both an H1 and H3 HA, where mice immunized with VacSIM had an increase in antigen-specific antibody titers and decreased disease severity and lung viral titers against H1N1 and H3N2 influenza challenges, respectively. Finally, it was determined that a single immunization with VacSIM and H1 HA could provide protection against lethal H1N1 challenge compared to a group without VacSIM. In summary, we demonstrate that use of the slow-release platform VacSIM can improve the host immune response to vaccination and increase protection against influenza infection.

Anna L. McCormick, Ted M. Ross, Donald A. Harn and Jarrod J. Mousa. 2025. Viruses 17, no. 9: 1190. https://doi.org/10.3390/v17091190