In Vitro Efficacy of Next Generation Dihydrotriazines and Biguanides Against Babesiosis and Malaria Parasites

Vydyam, P.; Chand, M.; Gihaz, S.; Renard, I.; Heffernan, G. D.; Jacobus, L. R.; Jacobus, D. P.; Saionz, K. W.; Shah, R.; Shieh, H.-M.; Terpinski, J.; Zhao, W.; Cornillot, E.; Ben Mamoun, C.

doi:10.1101/2024.03.20.585986

bioRxiv · 10.1101/2024.03.20.585986

In Vitro Efficacy of Next Generation Dihydrotriazines and Biguanides Against Babesiosis and Malaria Parasites

Vydyam, P.·Chand, M.·Gihaz, S.·Renard, I.·Heffernan, G. D.·Jacobus, L. R.·Jacobus, D. P.·Saionz, K. W.·Shah, R.·Shieh, H.-M.·Terpinski, J.·Zhao, W.·Cornillot, E.·Ben Mamoun, C.

View original source ↗Export metadata ↓

Abstract

Babesia and Plasmodium pathogens, the causative agents of babesiosis and malaria, are vector-borne intraerythrocytic protozoan parasites, posing significant threats to both human and animal health. The widespread resistance exhibited by these pathogens to various classes of antiparasitic drugs underscores the need for the development of novel and more effective therapeutics strategies. Antifolates have long been recognized as attractive antiparasitic drugs as they target the folate pathway, which is essential for the biosynthesis of purines and pyrimidines, and thus are vital for the survival and proliferation of protozoan parasites. More efficacious and safer analogs within this class are needed to overcome challenges due to resistance to commonly used antifolates such as the aminopyrimidine, pyrimethamine, and to address liabilities associated with the dihydrotriazines, WR99210 and JPC-2067. Here we utilized an in vitro culture condition suitable for continuous propagation of B. duncani, B. divergens, B. MO1 and P. falciparum in human erythrocytes to screen a library of 51 dihydrotriazines and 28 biguanides for their efficacy in vitro and to compare their potency and therapeutic indices across different species and isolates. We identified nine analogs that inhibit the growth of all species, including the P. falciparum pyrimethamine-resistant strain HB3 with IC50 values below 10 nM and demonstrated excellent therapeutic indices. These compounds hold substantial promise as lead antifolates for further development as broad-spectrum antiparasitic drugs.

Source connections

Published article ↗

Explore related subjects

microbiology Preprint

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Vydyam, P., Chand, M., Gihaz, S., Renard, I., Heffernan, G. D., Jacobus, L. R., Jacobus, D. P., Saionz, K. W., Shah, R., Shieh, H.-M., Terpinski, J., Zhao, W., Cornillot, E., Ben Mamoun, C.. 2024-03-21. In Vitro Efficacy of Next Generation Dihydrotriazines and Biguanides Against Babesiosis and Malaria Parasites. https://doi.org/10.1101/2024.03.20.585986

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Extreme temperature exposure has negative demographic consequences for Sulfolobus acidocaldarius

Microorganisms inhabiting geothermal springs and volcanic systems experience fluctuating temperatures that can periodically exceed their upper thermal limits, but the demographic consequences of such exposure remain poorly understood. Here, we investigated demographic responses of the thermophilic archaeon Sulfolobus acidocaldarius to an extreme temperature (94.1{degrees}C) under two regimes: sustained exposure varying in duration, and episodic exposure interspersed with recovery at a permissive temperature (75{degrees}C). Under sustained exposure, populations showed no detectable loss of viability after 15 min but declined thereafter, decreasing by approximately five orders of magnitude after 120 min. Under episodic exposure, populations remained viable across nine exposure-recovery cycles but declined in density with successive cycles. Similar responses were observed for three strains, including a DNA mismatch repair knockout ({Delta}nucS), indicating that mismatch repair deficiency did not affect viability or recovery. Together, these results demonstrate that S. acidocaldarius can withstand brief and repeated exposure to near-boiling temperatures, with mortality determined primarily by cumulative exposure duration rather than a fixed thermal threshold.

microbiology↗

bioRxiv2026

Bacteriophage and Antibiotic Resistance Are Positively Associated across a Phylogenetically Diverse Set of Clinical Pseudomonas aeruginosa Isolates

Co-administration of phages and antibiotics has been proposed as a therapeutic approach against antibiotic-resistant bacteria. The relationship, however, between antibiotic resistance and phage resistance in clinical isolates is unclear. Here, we examine associations between phage and antibiotic resistance profiles across a panel of Pseudomonas aeruginosa clinical isolates from the Centers for Disease Control (CDC) and Food and Drug Administration (FDA) Antimicrobial Resistance Isolate (ARI) Bank comprising 55 clinical strains with full genome sequences and antibiotic susceptibility testing (AST) data for 11 clinically relevant antibiotics. As phages in this study, we use three well-characterized, morphologically distinct phages, OMKO1, Luz19, and PAML31-1. We screen for phage resistance using a growth suppression assay, then conduct statistical analysis against antibiotic MIC (Minimum Inhibitory Concentration) data provided by the CDC to define association patterns across this dataset. We find multiple significant susceptibility correlations between pairs of antibiotics and phages, and a positive overall association between average phage resistance and antibiotic resistance across the 55 strains, even controlling for phylogenetic associations (=0.358, p<0.005). We conclude that phage and antibiotic resistance are positively associated across this clinical isolate collection, suggesting that the two resistance phenotypes are not independent in P. aeruginosa. These findings have implications for the development of phage-antibiotic cocktails.

microbiology↗

bioRxiv2026

The Estuary Effect: Variations in Temperature and Salinity Alter msh Promoter Activity in Vibrio cholerae

Vibrio cholerae, the facultative pathogen underlying cholera, naturally inhabits warm aquatic estuaries. Environmental persistence is enhanced by the ability of V. cholerae to colonize host reservoirs and form multicellular biofilms, causing seasonally endemic outbreaks in many tropical regions. Most toxigenic strains utilize the type IVa mannose-sensitive hemagglutinin (MSHA) pilus for host reservoir colonization and biofilm formation. Temperature and salinity can alter V. cholerae biofilm formation, yet their impact on MSHA production specifically remains largely unknown. Here, we utilized transcriptional reporters of predicted msh promoters (msh-P1/msh-P2/msh-P3) and functional assays, to determine temperature and salinity impacts on msh expression and pilus biogenesis. Under standard laboratory conditions (30{degrees}C, 1% NaCl) only msh-P1/P2 are active and inversely-coordinated with one another. Both msh-P1/P2 activity were elevated by high temperature (37{degrees}C) and low salinity (0.25%/0.5% NaCl), and reduced by low temperature (20{degrees}C/25{degrees}C) and high salinity (2%/3% NaCl). Temperature-mediated alterations in promoter activity were not immediately reflected in changes to cell-surface MSHA levels, whereas high salinity led to decreased MSHA production. Combining high temperature (37{degrees}C) and high salinity (2%/3% NaCl), attenuated the salinity-mediated reduction of msh-P1/P2 activity. Biofilm biomass levels were only substantially heightened at 25{degrees}C and 20{degrees}C, likely a result of no temperature-dependent changes in cell-surface MSHA, and additional temperature-controlled biofilm regulation previously described. We also found msh-P1/P2 promoter activity and MSHA production varies widely across toxigenic O1 and O139 serogroups despite complete sequence homology. These results shed new light on how key signals regulate MSHA pilus production to support V. cholerae persistence in aquatic environments.

microbiology↗