Biology subjects

Do, T.

Publications and source records attributed to Do, T..

At least 19 recordsLinked to original sources

bioRxiv2026

Tonotopic mapping in children shows an overrepresentation of high frequencies in autism

Altered sensitivity to sounds despite normal peripheral hearing is common in neurodevelopmental disorders but the underlying mechanisms remain poorly understood. Here we investigate tonotopic organization in 86 children (6-11 years) with autism spectrum and related neurodevelopmental disorders as well as typically developing (TD) peers, using a child-friendly, passive listening, functional magnetic resonance imaging design. In TD children, tonotopic maps in primary auditory cortex resembled the typical high-low-high frequency gradients previously reported in adults, while children with autism showed an overrepresentation of high frequencies consistent with what has been observed in animal models of autism. Higher frequency tuning further correlated with greater caregiver-reported sound but not touch sensitivities. Importantly, tonotopy is a core organizational feature of auditory cortex that develops early in life and remains relatively stable after the critical period of heightened plasticity ends. Thus, these results suggest that atypical auditory processing in autism may result from early disruption to tonotopic map formation. Longitudinal neuroimaging studies are needed to understand the genetic and environmental causes of altered auditory cortex topology and its long-term consequences for higher-level auditory, language, and social communication development.

neuroscience↗

bioRxiv2026

Cryptic Evolution of Heteroresistance as Adaptation to Treatment Interruptions

The evolution of antibiotic resistance is traditionally understood as a selective sweep to fixation, yielding easily detectable, population-wide resistance. Many clinical isolates, however, exhibit a subtle phenotype in which resistance remains hidden within a susceptible majority despite a clonal genetic background: a phenomenon clinically recognized as heteroresistance (HR). Treatment failure driven by HR has been widely reported across bacterial and fungal infections and in cancer therapy. To understand when and how HR evolves, and why it is selected over classical population-wide resistance, we conducted de novo evolution experiments starting from susceptible Escherichia coli and analyzed the genetic changes and fitness effects in the evolved strains. Prolonged gaps in antibiotic exposure are required for HR to evolve, implicating treatment interruptions as a key driver. HR emerges rapidly and reproducibly with minimal antibiotic use, yet its emergence is not readily detected by routine susceptibility testing. Unlike classical resistance, an evolved HR population partitions at the single-cell level into multiple phenotypes with distinct growth-resistance trade-offs. Their relative abundance shifts dynamically with antibiotic exposure, enabling robust population survival while avoiding the constitutive fitness burden associated with classical resistance. Despite this phenotypic flexibility, stable single mutations including a missense substitution and a short in-frame deletion are sufficient to generate HR, indicating a low evolutionary barrier. Additionally, we found that clinical isolates exhibit genetic and fitness signatures resembling those of our lab-evolved strains, suggesting that clinical HR emerges through the selective mechanism uncovered in our experiments. Together, our results establish HR as a readily evolvable adaptive strategy under treatment interruptions that leverages phenotypic flexibility to maintain resistance at minimal fitness cost, providing mechanistic insight into its emergence and prevalence.

evolutionary biology↗

bioRxiv2026

A method to synthesize analytical rhodoquinone standards for quantitative analysis in tissue specimen

Rhodoquinone (RQ) is a recently discovered component of the mammalian electron transport chain (ETC) with a high degree of tissue-specificity. Currently, a lack of pure analytical standards limits efforts to precisely quantify its levels using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and interrogate its biochemical functions within mammalian ETC complexes. Here, rhodoquinone-9 (RQ-9) and rhodoquinone-10 (RQ-10), and their isomeric by-products isorhodoquinone-9 (isoRQ-9) and isorhodoquinone-10 (isoRQ-10), were synthesized from ubiquinone-9 and ubiquinone-10 starting materials. Isomers were separated and purified by flash chromatography and structurally confirmed with nuclear magnetic resonance (NMR) spectroscopy. The chromatographic and fragmentation patterns of both the oxidized and reduced forms of these electron carriers were further characterized by LC-MS/MS, establishing signatures for their confident identification in lipidomics studies. LC-MS/MS analysis of murine kidney tissue with RQ-9 analytical standard spike-in corroborate the identity of the endogenous murine RQ-9 and enable absolute quantification of its levels. Thus, we synthesized and purified RQ-9 and RQ-10 analytical standards that will enable absolute quantification in mammalian tissues and in vitro reconstitution studies on RQ-9 and RQ-10 in the mammalian ETC.

biochemistry↗

bioRxiv2026

Toxic metals increase root hair density by reducing epidermal cell length

Root hair cells, which are instrumental in water and nutrient uptake, grow polarly from the epidermal cell layer of the root. Furthermore, plants growing in challenging climates and complex soil environments acclimatize their root hair phenotypes, either by altering root hair length or density. Toxic metal stress is one of the major environmental stresses faced by plant roots. In this study, we demonstrate that toxic metals, such as chromium and arsenite, increase root hair density as an adaptive response. Using the model plant Arabidopsis thaliana and other crops plants, like Zea mays and Triticum aestivum, we further discovered that increased root hair density is caused by shorter epidermal cell length rather than alteration of epidermal cell fate. This study highlights the adaptive cellular and anatomical features of roots during toxic metal stress in evolutionary diverse plant species.

plant biology↗

bioRxiv2025

'The ship is going down and we are powerless'- The Impact of Federal Funding Changes on Researchers Training the Next Generation of Scientists

IntroductionHistorically, federal grant terminations have been rare and almost exclusively used in cases of misconduct. Under the current presidential administration, however, grant terminations have been common, with thousands of grants terminated across federal agencies such as the National Institutes of Health (NIH) and the National Science Foundation. Although there have been scattered reports of the impact of these terminations on individual researchers, there has not yet been a systematic investigation of the impact on the overall scientific community. MethodsAs part of a survey for a larger study, we asked researchers involved in T32 training programs how likely they would be to go into science if they were a graduate student now (Likert-type item) and how federal funding changes have affected them and their labs (open-ended). We report mean and standard deviation for the Likert-type item (1=Not at all likely, 5=Extremely likely), and we performed inductive thematic analysis to analyze the open-ended responses. Two independent raters coded responses, developed a codebook, and applied the codebook to all responses. The interrater reliability was high, {kappa}=0.84. ResultsOf the 490 researchers invited to participate in the survey, 277 (response rate 56.5%) completed it in full. Participants were relatively unlikely to choose to pursue science again, with only about one-third being somewhat or more likely to do so. Two hundred twenty-three people responded to the open-ended item about how federal funding changes have affected them. Coding resulted in 48 unique codes which fell into four themes: Impact on Finances, Impact on Trainees, Impact on Science, and Well-being. Participants described instability in their labs, concern for trainees well-being and careers, concern about the future of the entire scientific enterprise, and negative impacts on their and others well-being. DiscussionOur data demonstrates the significant, overwhelmingly negative impact of the changes in federal funding on researchers involved in training the next generation of scientists. Not only are they concerned about how they can continue to do the work they have dedicated their lives to, but they are also worried about the future of science in the United States. This latter concern stems not only from the decreasing availability and reliability of federal funding but also due to the impact all this is having on trainees ability to do their research and find jobs where they can do science. These data are a call to action to our federal agencies, institutions, other agencies, and donors who understand the value of science to support researchers through these uncertain times. Otherwise, what has taken decades to build will be eliminated by a few anti-scientific decisions.

scientific communication and education↗

bioRxiv2025

A Co-Evolutionary Multi-Objective Framework for Joint Topology and Parameter Discovery in Gene Regulatory Networks

Inferring gene regulatory networks (GRN) poses a complex discrete-continuous, multi-objective optimization problem that requires the simultaneous discovery of both network topology and kinetic parameters. Current methods are often limited because they address these two challenges separately. We propose a novel co-evolutionary multi-objective framework that evolves topology and parameter populations in tandem to optimize three competing objectives: dynamic fidelity, network simplicity, and robustness. This algorithm utilizes biologically-inspired operators and is grounded in theoretical results on Pareto optimality for mixed discrete-continuous spaces. In computational experiments on synthetic benchmarks, our approach showed superior performance, attaining the lowest mean squared error in three of four test cases against single-objective and topology-fixed methods. The framework successfully discovers multiple functionally equivalent network configurations, a finding that highlights the degeneracy inherent in biological systems and offers practical insights for synthetic biology, where function is often prioritized over precise structural accuracy.

systems biology↗

bioRxiv2025

Forecasting Urban Wastewater Microbiome Dynamics Using a Digital Twin Framework

Urban wastewater microbiomes are complex and temporally dynamic, offering valuable insight into community-scale microbial ecology and potential public health trends. However, existing wastewater-based studies often remain descriptive, lacking tools for predictive modeling. In this study, we introduce a digital twin framework that forecasts microbial abundance trajectories in urban wastewater using an interpretable generative model, Q-net. Trained on a 30-week longitudinal metagenomic dataset from seven wastewater treatment plants, the model captures temporal microbial dynamics with high fidelity (R2 > 0.97 for key taxa; R2 = 0.998 at the final timepoint). Beyond accurate forecasting, Q-net provides transparent model structure through conditional inference trees and enables simulation of realistic microbial trends under hypothetical scenarios. This work demonstrates the potential of digital twins to move wastewater microbiome studies from static snapshots to dynamic, predictive systems, with broad implications for environmental monitoring and microbial ecosystem modeling.

bioinformatics↗

bioRxiv2025

Impact of serum versus anticoagulant-containing plasma on influenza virusneuraminidase-based serological assays

The influenza virus neuraminidase (NA) is a promising target for next-generation influenza vaccines but standardized protocols for NA-based serological assays are lacking. Previous studies have demonstrated discordant results from haemagglutination inhibition and live virus microneutralization assays when comparing matched serum and plasma samples. It is therefore important to consider is the choice of serum or plasma samples in assays measuring influenza virus NA-specific antibodies. Here, we compared antibody titres against influenza A and B virus NAs in matched serum and different types of plasma using an enzyme-linked lectin assay (ELLA) and an enzyme-linked immunosorbent assay (ELISA). We observed good correlations between titres determined in serum and different types of plasma. However, there was variable and often poor agreement in the nominal titre values obtained from serum and different kinds of plasma in both ELLA and ELISA, with plasma samples often resulting in lower titres compared to serum samples. We also found differences in NA-specific responses to seasonal influenza vaccination assessed in serum versus plasma. Overall, our data demonstrate discrepancies between NA-specific antibody measurements in serum and plasma. We recommend the consistent use of serum as an important part of standardising NA-based serological assays.

immunology↗

bioRxiv2025

VN1K: a genome graph-based and function-driven multi-omics and phenomics resource for the Vietnamese population

Vietnam, the 16th most populated nation, remains profoundly underrepresented in global genomic databases. Here, we present VN1K, a first-ever comprehensive and well-curated resource of multi-omics data with a wide-range of phenotypic information of 1,011 unrelated Vietnamese individuals. High-depth short-read whole-genome sequencing data were generated for all samples along with various - omic data, including microarray, long-read whole-genome sequencing, and RNA sequencing. Using a high-sensitivity variant detection pipeline, which included a pangenome graph reference and a deep-learning framework, we identified nearly 40 million variants of which 8.5 million are novel with nearly 900 thousand short insertions/deletions and 39 thousand structural variants. Specifically, VN1K featured a first-ever whole-genome methylation profile based on long read sequencing. A genotype imputation panel was also created with the highest accuracy on the Vietnamese population. Variants with significantly different allele frequencies in the Vietnamese population compared to others were found to be functionally significant, especially in genes associated with immune diseases (HLA-B, KIR3DL3, KIR2DL1, KIR2DL4) or drug responses (CYP2C19, CYP2D6, VKORC1, CYP2B6). We were also able to map various loci related to hepatitis B virus infection as well as six disease traits, including triglyceride levels, LDL-C, serum glucose levels, HbA1c, and levels of two liver enzymes (ALT and AST). VN1K dataset is accessible via genome.vinbigdata.org, an integrated platform with both linear and graph-based genome browser for facilitating data exploration, research, and applications in precision medicine.

genomics↗

bioRxiv2024

Cysimiditides: RiPPs with a Zn-tetracysteine motif and aspartimidylation

Aspartimidylation is a post-translational modification found in multiple families of ribosomally synthesized and post-translationally modified peptides (RiPPs). We recently reported on the imiditides, a new RiPP family in which aspartimidylation is the class-defining modification. Imiditide biosynthetic gene clusters encode a precursor protein and a methyltransferase that methylates a specific Asp residue, converting it to aspartimide. A subset of imiditides harbor a tetracysteine motif, so we have named these molecules cysimiditides. Here, using genome mining we show that there are 56 putative cysimiditides predicted in publicly available genome sequences, all within actinomycetota. We successfully heterologously expressed two examples of cysimiditides and showed that the major products are aspartimidylated and that the tetracysteine motif is necessary for expression. Cysimiditides bind a Zn2+ ion, presumably at the tetracysteine motif. Using in vitro reconstitution of the aspartimidylation reaction, we show that Zn2+ is required for methylation and subsequent aspartimidylation of the precursor protein. An AlphaFold 3 model of the cysimiditide from Thermobifida cellulosilytica shows a hairpin structure anchored by the Zn2+-tetracysteine motif with the aspartimide site in the hairpin loop. An AlphaFold 3 model of this cysimiditide in complex with its cognate methyltransferase suggests that the methyltransferase recognizes the Zn2+-tetracysteine motif to correctly dock the precursor protein. Cysimiditides expand the set of experimentally-confirmed RiPPs harboring aspartimides, and represent the first RiPP class that has an obligate metal ion. Table of Contents Figure O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=104 SRC="FIGDIR/small/616296v1_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@2879corg.highwire.dtl.DTLVardef@152b63org.highwire.dtl.DTLVardef@1d3ad25org.highwire.dtl.DTLVardef@c8d63_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2023

CREID- A ChemoReceptor-Effector Interaction Database

The ChemoReceptor-Effector Interaction Database (CREID) is a collection of bacterial chemoreceptor and effector protein and interaction data to understand the process that chemoreceptors and effectors play in various environments. Our website includes terms associated with chemosensory pathways to educate users and those involved in collaborative research to help them understand this complex biological network. It includes 2,440 proteins involved in chemoreceptor and effector systems from 7 different bacterial families with 1,996 chemoeffector interactions. It is available at https://react-creid.bicbioeng.org. Key HighlightsO_LICREID links bacterial chemoreceptors with their associated effectors. C_LIO_LIResearchers interested in what attracts or repels bacteria can use CREID as a comprehensive source for information. C_LIO_LIBiosensor developers can leverage CREID to discover better interactions for their applications. C_LIO_LICREID reveals knowledge gaps in chemoreceptor-effector interactions for both model and non-model organisms. C_LI

bioengineering↗

bioRxiv2023

Genome Mining and Discovery of Imiditides, a Novel Family of RiPPs with a Class-defining Aspartimide Modification

Ribosomally synthesized and post-translationally modified peptides (RiPPs) are a fascinating class of natural products of ribosomal origins. In the past decade, various sophisticated machine learning-based software packages have been established to discover novel RiPPs that do not resemble the known families. Instead, we argue that tailoring enzymes that cluster with various RiPP families can serve as effective bioinformatic seeds for novel RiPP discovery. Leveraging that O-methyltransferases homologous to protein isoaspartyl methyltransferases (PIMTs) are associated with lasso peptide, graspetide, and lanthipeptide biosynthetic gene clusters (BGCs), we utilized the C-terminal motif unique to RiPP-associated O-methyltransferases as the search query to discover a novel family of RiPPs, imiditides. Our genome-mining algorithm reveals a total of 670 imiditide BGCs, widely distributed in Gram-positive bacterial genomes. In addition, we demonstrate the heterologous production of the founding member of the imiditide family, mNmaAM, encoded in the genome of Nonomuraea maritima. In contrast to other RiPP associated PIMTs that recognize constrained peptides as substrates, the PIMT homolog in mNmaAM BGC, NmaM, methylates a specific Asp residue on the linear precursor peptide, NmaA. The methyl ester is then turned into an aspartimide spontaneously. The aspartimide moiety formed is unusually stable, leading to the accumulation of the aspartimidylated product in vivo. The substrate specificity is achieved by extensive charge-charge interactions between the precursor NmaA and the modifying enzyme NmaM suggested by both experimental validations as well as an AlphaFold model prediction. Our study suggests that PIMT-mediated aspartimide formation is an underappreciated backbone modification strategy in RiPP biosynthesis, compared to the well-studied backbone rigidification chemistries, such as thiazol(in)e and oxazol(in)e formations. Additionally, our findings suggest that aspartimide formation in Gram-positive bacterial proteomes are not limited to spontaneous protein aging and degradation. TOC Figure O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=110 SRC="FIGDIR/small/536058v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@a36867org.highwire.dtl.DTLVardef@1b6044org.highwire.dtl.DTLVardef@14d3036org.highwire.dtl.DTLVardef@98666a_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2022

A High-Throughput Screen Reveals the Structure-Activity Relationship of the Antimicrobial Lasso Peptide Ubonodin

The Burkholderia cepacia complex (Bcc) is a group of bacteria including several opportunistic human pathogens. Immunocompromised individuals and cystic fibrosis patients are especially vulnerable to serious infections by these bacteria, motivating the search for compounds with antimicrobial activity against the Bcc. The natural product ubonodin is a lasso peptide with promising activity against several Bcc species, working by inhibiting RNA polymerase in susceptible bacteria. In this study, we developed a high-throughput screen using next-generation sequencing to examine the fitness of a library of over 90,000 ubonodin variants, generating the most comprehensive dataset on lasso peptide activity so far. This screen revealed information regarding the structure-activity relationship of ubonodin over a large sequence space, indicating certain residues that can tolerate amino acid substitutions and still retain activity. Remarkably, the screen identified one variant with not only improved activity compared to wild-type ubonodin but also a sub-micromolar minimum inhibitory concentration (MIC) against a clinical isolate of the Bcc member Burkholderia cenocepacia. Ubonodin and several of the variants identified in this study had a lower MIC against certain Bcc strains than many clinically approved antibiotics. Finally, the large library size enabled us to develop DeepLasso, a deep learning model that can predict the RNAP inhibitory activity of an ubonodin variant.

biochemistry↗

bioRxiv2022

The Anti-Burkholderia Lasso Peptide Ubonodin Co-Opts the Siderophore Receptor PupB for Cellular Entry

New antibiotics are needed as bacterial infections continue to be a leading cause of death. Notorious among antibiotic-resistant bacteria is the Burkholderia cepacia complex (Bcc), which infects cystic fibrosis patients, causing lung function decline. We recently discovered a novel ribosomally synthesized and post-translationally modified peptide (RiPP), ubonodin, with potent activity against several Burkholderia pathogens. Ubonodin inhibits RNA polymerase, but only select Bcc strains were susceptible, indicating that having a conserved cellular target does not guarantee activity. Given the cytoplasmic target, we speculate that cellular uptake of ubonodin determines susceptibility. Here, we report a new outer membrane siderophore receptor, PupB, that is required for ubonodin uptake in B. cepacia. Loss of PupB renders B. cepacia resistant to ubonodin, whereas expressing PupB sensitizes a resistant strain. Thus, outer membrane transport is the major determinant of ubonodins spectrum of activity. We also show that PupB is activated by a TonB protein and examine a transcriptional pathway that further regulates PupB. Finally, we elucidate the complete cellular uptake pathway for ubonodin by also identifying its inner membrane transporter in B. cepacia. Our work unravels central steps in the mechanism of action of ubonodin and establishes a general framework for dissecting RiPP function.

microbiology↗

bioRxiv2022

Metal cofactor stabilization by a partner protein is a widespread strategy employed for amidase activation

Construction and remodeling of the bacterial peptidoglycan (PG) cell wall must be carefully coordinated with cell growth and division. Central to cell wall construction are hydrolases that cleave bonds in peptidoglycan. These enzymes also represent potential new antibiotic targets. One such hydrolase, the amidase LytH in Staphylococcus aureus, acts to remove stem peptides from PG, controlling where substrates are available for insertion of new PG strands and consequently regulating cell size. When it is absent, cells grow excessively large and have division defects. For activity, LytH requires a protein partner, ActH, that consists of an intracellular domain, a large rhomboid protease domain, and three extracellular tetratricopeptide repeats (TPRs). Here we demonstrate that the amidase-activating function of ActH is entirely contained in its extracellular TPRs. We show that ActH binding stabilizes metals in the LytH active site, and that LytH metal binding in turn is needed for stable complexation with ActH. We further present a structure of a complex of the extracellular domains of LytH and ActH. Our findings suggest that metal cofactor stabilization is a general strategy used by amidase activators and that ActH houses multiple functions within a single protein. SIGNIFICANCE STATEMENTThe Gram-positive pathogen Staphylococcus aureus is a leading cause of antibiotic resistance-associated death in the United States. Many antibiotics used to treat S. aureus, including the beta-lactams, target biogenesis of the essential peptidoglycan (PG) cell wall. Some hydrolases play important roles in cell wall construction and are potential antibiotic targets. The amidase LytH, which requires a protein partner, ActH, for activity, is one such hydrolase. Here, we uncover how the extracellular domain of ActH binds to LytH to stabilize metals in the active site for catalysis. This work advances our understanding of how hydrolase activity is controlled to contribute productively to cell wall synthesis.

microbiology↗

bioRxiv2021

The C. albicans virulence factor Candidalysin polymerizes in solution to form membrane pores and damage epithelial cells.

The pathogenic fungus Candida albicans causes severe invasive candidiasis. C. albicans infection requires the action of the virulence factor Candidalysin (CL), which damages the plasma membrane of the target human cells. However, the molecular mechanism that CL uses to permeabilize membranes is poorly understood. We employed complementary biophysical, modeling, microscopy, and cell biology methods to reveal that CL forms membrane pores using a unique molecular mechanism. Unexpectedly, it was observed that CL readily assembles into linear polymers in solution. The basic structural unit in polymer formation is a CL 8-mer, which is sequentially added into a string configuration. Finally, the linear polymers can close into a loop. Our data indicate that CL loops spontaneously insert into the membrane to become membrane pores. We identified a CL mutation (G4W) that inhibited the formation of polymers in solution and prevented formation of pores in different synthetic lipid membranes systems. Studies in epithelial cells showed that G4W CL failed to activate the danger response signaling pathway, a hallmark of the pathogenic effect of CL. These results indicate that CL polymerization in solution is a necessary step for the damage of cellular membranes. Analysis of thousands of CL pores by atomic force microscopy revealed the co-existence of simple depressions and complex pores decorated with protrusions. Imaging and modeling indicate that the two types of pores are formed by CL molecules assembled into alternate orientations. We propose that this structural rearrangement represents a maturation mechanism that might stabilize pore formation to achieve more robust cellular damage. Taken together, the data show that CL uses a previously unknown mechanism to damage membranes, whereby pre-assembly of CL loops in solution directly leads to formation of membrane pores. Our investigation not only unravels a new paradigm for the formation of membrane pores, but additionally identifies CL polymerization as a novel therapeutic target to treat candidiasis.

biophysics↗

bioRxiv2020

Single Cell and Spatial Transcriptomics Defines the Cellular Architecture of the Antimicrobial Response Network in Human Leprosy Granulomas

Granulomas are complex cellular structures comprised predominantly of macrophages and lymphocytes that function to contain and kill invading pathogens. Here, we investigated single cell phenotypes associated with antimicrobial responses in human leprosy granulomas by applying single cell and spatial sequencing to leprosy biopsy specimens. We focused on reversal reactions (RR), a dynamic process in which some patients with disseminated lepromatous leprosy (L-lep) transition towards self-limiting tuberculoid leprosy (T-lep), mounting effective antimicrobial responses. We identified a set of genes encoding proteins involved in antimicrobial responses that are differentially expressed in RR versus L-lep lesions, and regulated by IFN-{gamma} and IL-1{beta}. By integrating the spatial coordinates of the key cell types and antimicrobial gene expression in RR and T-lep lesions, we constructed a map revealing the organized architecture of granulomas depicting compositional and functional layers by which macrophages, T cells, keratinocytes and fibroblasts contribute to the antimicrobial response.

immunology↗

bioRxiv2020

Molecular detection of pathogens in ticks and fleas collected from companion dogs and cats in East and Southeast Asia

Ticks and fleas are considered amongst the most important arthropod vectors of medical and veterinary concern due to their ability to transmit pathogens to a range of animal species including dogs, cats and humans. By sharing a common environment with humans, companion animal-associated parasitic arthropods may potentially transmit zoonotic vector-borne pathogens (VBPs). This study aimed to molecularly detect pathogens from ticks (n = 392) and fleas (n = 248) collected from companion dogs and cats in East and Southeast Asia. Of the 392 ticks tested, 37 (9.4%) scored positive for at least one pathogen with Hepatozoon canis being the most prevalent (5.4%), followed by Ehrlichia canis (1.8%), Babesia vogeli (1%), Anaplasma platys (0.8%) and Rickettsia spp. (1%) [including Rickettsia sp. (0.5%), Rickettsia asembonensis (0.3%), Rickettsia felis (0.3%)]. Out of 248 fleas tested, 106 (42.7%) were harboring at least one pathogen with R. felis being the most common (19.4%), followed by Bartonella spp. (16.5%), Rickettsia asembonensis (10.9%) and Candidatus Rickettsia senegalensis (0.4%). Furthermore, 35 Rhipicephalus sanguineus sensu lato ticks were subjected to phylogenetic analysis, of which 34 ticks belonged to the tropical and only one belonged to the temperate lineage (Rh. sanguineus sensu stricto). Our data reveals the circulation of different VBPs in ticks and fleas of dogs and cats from Asia, including zoonotic agents, which may represent a potential risk to animal and human health. Author summaryTicks and fleas are among the most important vectors of pathogens infesting many animal species including humans worldwide. Although a number of vector-borne pathogens have been detected in dogs and cats from East and Southeast Asia, investigation in ticks and fleas collected from them are scant. In order to provide an overview of the pathogens circulating in ticks and fleas from companion dogs and cats in Asia, ticks (n = 392) and fleas (n = 248) were collected from privately-owned dogs and cats from China, Taiwan, Indonesia, Malaysia, Singapore, Thailand, Philippines and Vietnam and molecularly screened for the presence of pathogens. Overall, multiple pathogens were found in ticks (i.e., Babesia vogeli, Hepatozoon canis, Ehrlichia canis, Anaplasma platys and Rickettsia spp.) and fleas (i.e., Rickettsia spp. and Bartonella spp.) from the sampling areas. Of the ticks tested, 9.4% scored positive for at least one pathogen and of fleas 42.7% harbored at least one pathogen with Rickettsia felis being the most common (19.4%). Overall, of the detected pathogens, R. felis stood out as the most important due to its zoonotic potential. The result of this study should increase awareness among pet owners and veterinary practitioners regarding the importance of ticks and fleas, and their transmitted pathogens.

molecular biology↗