Host Pathogen Research Articles

Machine Learning-based Host–Pathogen Protein–Protein Interaction Prediction

Machine Learning-based Host–Pathogen Protein–Protein Interaction Prediction

Knockin’ on Cell’s Door: Influenza A Virus Adsorption and Its Pharmacological Inhibition

Influenza A virus (IAV) is a widespread human respiratory pathogen that contributes significantly to morbidity and mortality worldwide. The adsorption of the virus into the cell surface is the earliest stage of its replication cycle. The key role of N-linked sialic acids (SIAs) as receptors for binding to IAV’s hemagglutinin (HA) has long been acknowledged. The molecular specificity of this interaction is a key factor in host range, pathogenicity, and transmissibility of various IAV subtypes. Along with this, a number of recent studies have introduced significant complexity into the picture of IAV adsorption and revealed a multitude of new molecules on host cell surfaces to serve as receptors and/or co-receptors for IAV attachment. For successful internalization of the adsorbed virus, downstream signal transduction is necessary to activate effector endocytosis mechanisms. In recent years, our understanding of the sophistication and variability of signal transduction pathways in the virus attachment site has significantly expanded, with the help of research techniques like fluorescence imaging of individual viruses in real-time, dominant-negative mutants, siRNA knockdowns, protein kinase selective inhibitors, phosphoproteome profiling, and others. These approaches deepen our knowledge of the molecules involved in the early stages of the IAV life cycle and also serve as the basis for the development of new effective antiviral drugs. In our review, we analyze recent publications on the mechanisms of IAV adsorption, newly discovered receptors for virus attachment, and signal transmission in the site of the adsorbed virion. Besides this, we consider new data on the development of selective inhibitors as antiviral drugs aimed at both viral and cellular factors of IAV adsorption.

Comparative transcriptomics reveal stage-dependent parasitic adaptations in the myxozoan Sphaerospora molnari

BackgroundParasitism as a life strategy has independently evolved multiple times within the eukaryotic tree of life. Each lineage has developed mechanisms to invade hosts, exploit resources, and ensure replication, but our knowledge of survival mechanisms in many parasitic taxa remain extremely limited. One such group is the Myxozoa, which are obligate, dixenous cnidarians. Evidence suggests that myxozoans evolved from free-living ancestors to endoparasites around 600 million years ago and are likely one of the first metazoan parasites on Earth. Some myxozoans pose significant threats to farmed and wild fish populations, negatively impacting aquaculture and fish stocks; one such example is Sphaerospora molnari, which forms spores in the gills of common carp (Cyprinus carpio), disrupting gill epithelia and causing somatic and respiratory failure. Sphaerospora molnari undergoes sequential development in different organs of its host, with large numbers of morphologically distinct stages occurring in the blood, liver, and gills of carp. We hypothesize that these parasite life-stages differ in regards to their host exploitation, pathogenicity, and host immune evasion strategies and mechanisms. We performed stage-specific transcriptomic profiling to identify differentially expressed key functional gene groups that relate to these functions and provide a fundamental understanding of the mechanisms S. molnari uses to optimize its parasitic lifestyle. We aimed to identify genes that are likely related to parasite pathogenicity and host cell exploitation mechanisms, and we hypothesize that genes unique to S. molnari might be indicative of evolutionary innovations and specific adaptations to host environments.ResultsWe used parasite isolation protocols and comparative transcriptomics to study early proliferative and spore-forming stages of S. molnari, unveiling variation in gene expression between each stage. We discovered several apparent innovations in the S. molnari transcriptome, including proteins that are likely to function in the uptake of previously unknown key nutrients, immune evasion factors that may contribute to long-term survival in hosts, and proteins that likely improve adhesion to host cells that may have arisen from horizontal gene transfer. Notably, we identified genes that are similar to known virulence factors in other parasitic organisms, particularly blood and intestinal parasites like Plasmodium, Trypanosoma, and Giardia. Many of these genes are absent in published cnidarian and myxozoan datasets and appear to be specific to S. molnari; they may therefore represent potential innovations enabling Sphaerospora to exploit the host’s blood system.ConclusionsIn order to address the threat posed by myxozoans to both cultured fish species and wild stocks, it is imperative to deepen our understanding of their genetics. Sphaerospora molnari offers an appealing model for stage-specific transcriptomic profiling and for identifying differentially expressed key functional gene groups related to parasite development. We identified genes that are thus far unique to S. molnari, which reveal their evolutionary novelty and likely role as adaptations to specific host niches. In addition, we describe the pathogenicity-associated genetic toolbox of S. molnari and discuss the implications of our discoveries for disease control by shedding light on specific targets for potential intervention strategies.

Host Jumps and Pathogenicity of Botryosphaeriaceae Species on Grapevines (Vitis vinifera) in Chile

Botryosphaeria dieback disease is a significant grapevine trunk disease (GTD) caused by species of Botryosphaeriaceae in Chile and worldwide. Moreover, Botryosphaeriaceae have been described attacking fruit and nut crops in Chile. However, it remains unknown whether fungal isolates from tree hosts have the potential to infect grapevines in Chile. The aggressiveness and potential cross infection of species of Botryosphaeriaceae collected from crops (grapevines, apples, blueberries, and walnuts), was assessed on grapevines. Plant materials, including nursery cuttings, lignified canes, and green shoots of grapevine cultivars (Cabernet Sauvignon, Syrah, Sauvignon Blanc, Malbec, Aspirant Bouschet, and Merlot), were inoculated with Diplodia mutila, D. seriata, Dothiorella sarmentorum, Lasiodiplodia theobromae, Neofusicoccum arbuti, and N. parvum, under greenhouse and vineyard conditions. Regardless of the origin of the isolates, most species of Botryosphaeriaceae were pathogenic on plant materials, causing necrotic lesions of mean lengths from 11.9 to 86.2 mm using mycelial suspension and from 24.8 to 253.7 mm with mycelial plugs. Notably, Neofusicoccum species were the most aggressive, regardless of host origin. Other less aggressive species included L. theobromae, D. mutila, and D. seriata isolated from apple and walnut. This study highlights the potential of species of Botryosphaeriaceae from alternative fruit hosts as inoculum sources for grapevines in Chile.

Synthetic Biology-Based Approaches to Investigate Host–Pathogen Interactions

The increasing prevalence of multi-drug-resistant (MDR) bacterial pathogens presents a critical global health threat, highlighting the urgent need for innovative approaches to understanding bacterial pathogenesis and developing effective therapies. This review underscores the potential of synthetic biology in elucidating host–pathogen interactions and facilitating the creation of advanced diagnostic tools and targeted therapies to combat MDR infections. We first explore CRISPR-based strategies that modulate essential gene expression, providing insights into the molecular mechanisms underlying host–pathogen interactions. Next, we discuss engineered microbial synthetic circuits for rapid pathogen detection by identifying molecular signatures involved in interspecies communication and facilitating swift pathogen elimination. Additionally, we explore phage therapy (PT), which leverages bacteriophages to selectively target and eliminate specific bacterial pathogens, presenting a targeted and promising approach to combat MDR infections. Finally, we review the application of organ-on-a-chip (OOAC) technology, which overcomes the limitations of animal models in predicting human immune responses by using microfluidic devices that simulate organ-level physiology and pathophysiology, thereby enabling more accurate disease modeling, drug testing, and the development of personalized medicine. Collectively, these synthetic biology tools provide transformative insights into the molecular mechanisms of host–pathogen interactions, advancing the development of precise diagnostic and therapeutic strategies against MDR infections.

Prior heat waves improve survival of field but not domesticated populations of tobacco hornworm exposed to repeated bacterial infections

Abstract In insects and other invertebrates, prior pathogen exposures can improve immune responses and survival to subsequent infections through immune priming. Alternatively, stress and metabolic costs of multiple infections can impair host immunity and survival. The effects of high‐temperature extremes on host–pathogen interactions are not well understood despite the increasing occurrence of heat waves caused by climate change. The response of insects to heat waves and pathogens depends on recent evolutionary history with selective pressures. Domestication of insect pests has occurred in lab colonies of model species, reducing selective pressures for immune and heat stress responses. Lab strains are often used in immunological or heat stress experiments to represent wild field strains, but the efficacy of this approach is seldom evaluated. Using the tobacco hornworm (Manduca sexta), we tested the impact of a heat wave during initial pathogen exposure on survival of a secondary infection with Bacillus thuringiensis bacteria. We used a domesticated lab population and a naturally occurring field population of M. sexta to evaluate the impacts of recent domestication on immune and thermal responses. A heat wave during initial infection significantly increased survival of the secondary B. thuringiensis infection in the field, but not the lab population of M. sexta. In the field population, survival of the repeated infection was temperature dependent: exposure to an initial infection event reduced survival of the secondary infection at the control temperature regime, consistent with a stress effect. However, a heat wave during the initial infection event increased survival of the secondary infection, consistent with immune priming effects. The results of this study demonstrate that (a) insect response to thermal stress and pathogens can depend on recent domestication and (b) responses of hosts to repeat pathogen exposures can be temperature‐dependent, suggesting that cross‐talk between the heat stress and immune memory pathways may have important consequences for host–pathogen outcomes under heat wave events. Read the free Plain Language Summary for this article on the Journal blog.

Q Fever Vaccines: Unveiling the Historical Journey and Contemporary Innovations in Vaccine Development

Q fever is a zoonotic disease caused by the obligate intracellular bacterium Coxiella burnetii that presents significant challenges for global public health control. Current prevention relies primarily on the whole-cell vaccine “Q-VAX”, which despite its effectiveness, faces important limitations including pre-screening requirements and reactogenicity issues in previously sensitized individuals. This comprehensive review examines the complex interplay between pathogen characteristics, host immune responses, and vaccine development strategies. We analyze recent advances in understanding C. burnetii’s molecular pathogenesis and host–pathogen interactions that have informed vaccine design. The evolution of vaccine approaches is evaluated, from traditional whole-cell preparations to modern subunit, DNA, and multi-epitope designs. Particular attention is given to innovative technologies, including reverse vaccinology and immunoinformatics, that have enabled the identification of novel antigenic targets. Recent clinical data demonstrating the safety and immunogenicity of next-generation vaccine candidates are presented, alongside manufacturing and implementation considerations. While significant progress has been made in overcoming the limitations of first-generation vaccines, challenges remain in optimizing immunogenicity while ensuring safety across diverse populations. This review provides a critical analysis of current evidence and future directions in Q fever vaccine development, highlighting promising strategies for achieving more effective and broadly applicable vaccines.

Extended receptor repertoire of an adenovirus associated with human obesity.

Human adenovirus type 36 (HAdV-D36) has been putatively linked to obesity in animals and has been associated with obesity in humans in some but not all studies. Despite extensive epidemiological research there is limited information about its receptor profile. We investigated the receptor portfolio of HAdV-D36 using a combined structural biology and virology approach. The HAdV-D36 fiber knob domain (FK), which mediates the primary attachment of many HAdVs to host cells, has a significantly elongated DG loop that alters known binding interfaces for established adenovirus receptors such as the coxsackie- and adenovirus receptor (CAR) and CD46. Our data suggest that HAdV-D36 attaches to host cells using a versatile receptor pool comprising sialic acid-containing glycans and CAR. Sialic acids are recognized at the same binding site used by other HAdVs of species D such as HAdV-D37. Using glycan microarrays, we demonstrate that HAdV-D36 displays a binding preference for glycans containing a rare sialic acid variant, 4-O,5-N-diacetylneuraminic acid, over the more common 5-N-acetylneuraminic acid. To date, this sialic acid variant has not been detected in humans, although it can be synthesized by various animal species, including a range of domestic and livestock animals. Taken together, our results indicate that HAdV-D36 has evolved to recognize a specialized set of primary attachment receptors that are different from known HAdV types and coincides with a unique host range and pathogenicity profile.

How hosts and pathogens choose the strengths of defense and counterdefense: a game-theoretical view

Host–pathogen interactions consist of an attack by the pathogen, frequently a defense by the host and possibly a counterdefense by the pathogen. Here, we present a game-theoretical approach to describe such interactions. We consider a game where the host and pathogen are players and can choose between the strategies of defense (or counterdefense) and no response. Specifically, they may or may not produce a toxin and an enzyme degrading the toxin, respectively. We consider that the host and pathogen must also incur a cost for toxin or enzyme production. We highlight both the sequential and non-sequential versions of the game and determine the Nash equilibria. Furthermore, we resolve a paradox occurring in that interplay. If the inactivating enzyme is very efficient, producing the toxin becomes useless, leading to the enzyme being no longer required. Then, the production of the defense becomes useful again. In game theory, such situations can be described by a generalized matching pennies game. As a novel result, we find under which conditions the defense cycle leads to a steady state or an oscillation. We obtain, for saturating dose–response kinetics and considering monotonic cost functions, “partial (counter)defense” strategies as pure Nash equilibria. This implies that producing a moderate amount of toxin and enzyme is the stable situation in this game.

P-2237. Mortality and Causative Pathogens of Sepsis Differ by Molecular Phenotype in a Secondary Analysis of MARS

Abstract Background Heterogeneity of host response has been a barrier to identifying novel therapies in sepsis. Two molecular phenotypes of critical illness, called the Hyperinflammatory and Hypoinflammatory, have been identified in multiple cohorts of sepsis and ARDS ( >12,000 patients), with divergent biology, clinical course, and responses to therapy1. We evaluated whether these phenotypes were identifiable in MARS-- a large observational cohort of critically ill patients-- and whether the pathogens present in each phenotype differed. Methods MARS recruited critically ill patients from two Dutch ICUs. Only patients meeting sepsis or ARDS diagnostic criteria were included for this analysis. We applied latent class analysis (LCA) to vital signs, clinical laboratory values, and protein biomarkers from Day 1 of ICU admission in 1,485 patients. LCA models with 1-5 classes were fitted. We assigned class membership using the best fitting model and compared characteristics between classes. The present classes’ overlap with prior phenotypes was evaluated by comparison to an extensively validated parsimonious model,2 trained previously to classify molecular phenotypes. Results A two-class model best fit the cohort (VLMR p< .001), and the parsimonious model and multivariate profiles suggested high overlap (AUC=.929) with previously described ‘Hypoinflammatory’ (Class 1; n=895) and ‘Hyperinflammatory’ (Class 2; n=590) phenotypes (Figure 1). Bacteremia was more prevalent in the Hyperinflammatory phenotype (27.2% vs 7.8%; p< .001), with Enterobacteriaceae as the most prevalent species. For primary infection sites, lower respiratory tract was more common in the Hypoinflammatory (56% vs 36%) and abdomen more common in the Hyperinflammatory phenotype (26% vs 9%). Mortality was significantly higher in the Hyperinflammatory phenotype at both 30 days (OR=2.54, CI95%= 2.003—3.235 ) and 90 days (OR=2.41, CI95% = 1.925—3.016; both p< .001). Conclusion In MARS, we identified the previously described Hypo- and Hyperinflammatory phenotypes with divergent host response, pathogen profiles, and outcomes. These findings suggest that host phenotype signatures in part may be driven by sites of infection and pathogen species. Disclosures Lieuwe D.J. Bos, MD-PhD, Astra Zeneca: Advisor/Consultant|CSL Behring: Advisor/Consultant|Impentri: Advisor/Consultant|Novartis: Advisor/Consultant|Scailyte: Advisor/Consultant|Sobi: Advisor/Consultant Pratik Sinha, MBChB/PhD, AstraZeneca: Advisor/Consultant|Prenosis Inc: Board Member Carolyn S. Calfee, MD, Cellenkos: Advisor/Consultant|Gen1e Life Sciences: Advisor/Consultant|Janssen: Advisor/Consultant|NGMBio: Advisor/Consultant|Santhera: Advisor/Consultant|Vasomune: Advisor/Consultant

A Comparative Analysis of Sialic Acid Binding Proteins for Better Understanding of their Role in Host Pathogen Interaction and Human Health: A Bioinformatics Perspective

Sialic acids, especially N-acetylneuraminic acid, serve as pivotal molecular interfaces between host tissues and invading pathogens by modulating attachment, immune evasion, and metabolic processes. In this study, we performed a comprehensive bioinformatics analysis of sialic acid binding proteins (SABPs) to unravel their structural diversity, evolutionary distribution, and functional roles across bacteria and viruses. A curated dataset of 209 SABPs was retrieved from the UniProt database, with inclusion criteria emphasizing annotated sialic acid binding activity and sequence completeness. Notably, 208 proteins in this collection are backed by experimentally determined 3D structures, enabling in-depth examination of their binding sites and catalytic domains. Gene Ontology (GO) analyses revealed that these proteins are predominantly involved in critical biological processes related to host-pathogen interaction, such as virion attachment to host cells, membrane fusion, and carbohydrate metabolism. Molecular function terms were dominated by host cell surface receptor binding, carbohydrate binding, and hydrolase activities targeting glycosyl bonds. Cellular component annotations highlighted membrane localization and extracellular secretions, consistent with roles in mediating initial host contact and pathogen dissemination. Taxonomic assessments showed a strong representation of Orthomyxoviridae, underlining the importance of hemagglutinin and neuraminidase in influenza viruses, while bacterial families such as Clostridiaceae and Staphylococcaceae contributed SABPs involved in sialic acid catabolism and toxin-mediated virulence. Family-level clustering pinpointed hemagglutinins, neuraminidases (glycosyl hydrolases GH33 and GH34), and immunoglobulin superfamily members—further emphasizing the widespread evolutionary adoption of sialic acid recognition. These findings collectively underscore the centrality of SABPs in host-pathogen interactions and offer a valuable resource for future research aimed at leveraging sialic acid biology for therapeutic and diagnostic advancements.

An invasive pathogen generally contracts species to their niche cores, not margins

Quantifying how species' distributions contract in response to threats can reveal pathways of decline and the role of environmental conditions in moderating threat impacts. Two general patterns of niche contraction have been described: ecological marginalization, where species contract away from threat impacts to peripheral, sub‐optimal areas of their niche, and; contraction to the core, where species contract toward their niche center where their fitness and capacity to withstand threat impacts is highest. Recent work has described widespread ecological marginalization in declining mammal species, for which land use change and overexploitation are key threats. Different threatening processes could result in contrasting patterns of niche contraction, although this has not been well‐studied. Here, we examine patterns of realized niche contraction in Australian frog species impacted by the emergence of chytrid fungus Batrachochytrium dendrobatidis, a pathogen that has driven catastrophic amphibian declines globally. We quantified changes in species' environmental niche space following chytrid emergence and documented a pattern of contraction toward the niche core in declining species. We develop and apply a novel approach to show that these niche contractions are driven by losses in a subset of niche space, suggesting population extinctions due to chytrid are driven by factors shaping both pathogen fitness (threat impact) and host fitness (threat tolerance). Species declines have been concentrated in high elevation areas with cooler temperatures, which are more physiologically suitable for the pathogen and constrain the resilience of frog hosts at both individual and population levels. Given the contrast between our results and widespread ecological marginalization in mammals, we propose that while a given threat may result in common patterns of decline among affected species, patterns of decline may vary considerably between threatening processes and among taxa.

Fungal Metabolomics: A Comprehensive Approach to Understanding Pathogenesis in Humans and Identifying Potential Therapeutics

Metabolomics has emerged as a transformative tool in the study of microbes, including pathogenic fungi, facilitating the identification of unique metabolic profiles that elucidate their pathogenic mechanisms, host interactions, and treatment resistance. This review highlights key applications of metabolomics in understanding fungal metabolites essential for human virulence, such as mycotoxins produced by various fungal species, including Aspergillus fumigatus (gliotoxin, fumagillins) and Candida species (phenylethyl alcohol, TCA cycle metabolites), and secondary metabolites that contribute to pathogenicity. It also explores the metabolic adaptations of fungi in relation to drug resistance and biofilm formation, revealing alterations in key metabolic pathways during infection, as seen in C. albicans and C. auris. Furthermore, metabolomics aids in deciphering host–pathogen interactions, showcasing how fungi like Cryptococcus neoformans and Candida modify host metabolism to promote survival and evade immune responses. The study of antifungal resistance mechanisms has also benefited from metabolomic approaches, identifying specific metabolite patterns that signify resistance, such as in Candida albicans and Candidozyma (Candida) auris, and informing new therapeutic strategies. The integration of metabolomics with other omics technologies is paving the way for a comprehensive understanding of fungal biology and pathogenesis. Such multi-omics approaches are crucial for discovering new therapeutic targets and developing innovative antifungal treatments. Thus, the purpose of this review is to provide an overview of how metabolomics is revolutionizing our understanding of fungal pathogenesis, drug resistance, and host interactions, and to highlight its potential for identifying new therapeutic targets and improving antifungal strategies.

Immunological findings of West Caucasian bat virus in an accidental host.

Although all lyssaviruses cause fatal encephalomyelitis in mammals, they display a different host tropism and pathogenicity, with the ecology of Rabies virus (RABV) continually evolving and adapting to new host species. In 2020, West Caucasian bat virus (WCBV) was identified as the causative agent of rabies in a domestic cat in Italy. This event raised concerns about its public health consequences, due to the absence of biologicals against the infection. Our study investigates the host immune response triggered by WCBV in comparison with a pathogenic strain of RABV and the low pathogenic Duvenhage lyssavirus (DUVV), as a proxy to understand the mechanisms leading to lyssavirus spillover and pathogenicity. We overall confirm that previous evidence indicating an inverse relationship between lyssavirus pathogenicity and immune response is applicable for WCBV as well. Importantly, this work represents the first transcriptomic analysis of the WCBV interaction in the central nervous system with an accidental host.

A framework to predict zoonotic hosts under data uncertainty: A case study on betacoronaviruses

Abstract Modelling approaches aimed at identifying unknown hosts of zoonotic pathogens have the potential to make high‐impact contributions to global strategies for zoonotic risk surveillance. However, geographical and taxonomic biases in host–pathogen associations affect the reliability of models and their predictions. Here, we propose a methodological framework to mitigate the effect of biases in host–pathogen data and account for uncertainty in models' predictions. Our approach involves identifying ‘pseudo‐negative’ species and integrating sampling biases into the modelling pipeline. We present an application on the genus Betacoronavirus and provide estimates of mammal‐borne betacoronavirus hazard at a global scale. We show that the inclusion of pseudo‐negatives in the analysis improved the overall validation performance of our model when compared to a model that does not use pseudo‐negatives, especially reducing the rate of false positives. Results of our application unveil currently unrecognised hotspots of betacoronavirus hazard in subequatorial Africa and the Americas. Our approach addresses crucial limitations in host–pathogen association modelling, with important downstream implications for zoonotic risk assessments. The proposed framework is adaptable to different multi‐host disease systems and may be used to identify surveillance priorities as well as knowledge gaps in zoonotic pathogens' host‐range.

Self-Immobilizing Fluorogenic Probe for In Situ Labeling of Granzyme B Activity in Host Immune Response to Bacterial Infections.

Bacterial infections, particularly those caused by drug-resistant bacteria, represent a pressing global health challenge. During the interaction between pathogen infection and host defense, bacterial infections initiate the host's immune response, which involves the activation of proteases that play a critical role in antibacterial defense. Granzyme B (GzmB), a key immune-related biomarker associated with cytotoxic T lymphocytes (CTLs), plays a pivotal role in this process. Therefore, detecting the activity of GzmB is crucial for understanding the host immune response to bacterial infections and for developing therapeutic strategies to overcome bacterial virulence. In this study, we designed and synthesized three granzyme B-activated near-infrared molecular probes. Among them, the probe HCy-F demonstrates in situ imaging capability, enabling precise quantification of GzmB activity. This development offers a valuable tool for monitoring immune responses and optimizing immunotherapy approaches for combating drug-resistant pathogens.

Understanding Host–Pathogen Interactions in Congenital Chagas Disease Through Transcriptomic Approaches

Chagas disease, caused by Trypanosoma cruzi, is a parasitic zoonosis with significant health impacts, particularly in Latin America. While traditionally associated with vector-borne transmission, increased migration has expanded its reach into urban and non-endemic regions. Congenital transmission has become a critical route of infection, involving intricate maternal–fetal immune interactions that challenge diagnosis and treatment. This review synthesizes findings from three RNA-seq studies that explore the molecular underpinnings of congenital Chagas disease, emphasizing differentially expressed genes (DEGs) implicated in host–pathogen interactions. The DAVID tool analysis highlighted the overexpression of genes associated with the innate immune response, including pro-inflammatory cytokines that drive chemotaxis and neutrophil activation. Additionally, calcium-dependent pathways critical for parasite invasion were modulated. T. cruzi exploits the maternal–fetal immune axis to establish a tolerogenic environment conducive to congenital transmission. Alterations in placental angiogenesis, cellular regeneration, and metabolic processes further demonstrate the parasite’s ability to manipulate host responses for its survival and persistence. These findings underscore the complex interplay between the host and pathogen that facilitates disease progression. Future research integrating transcriptomic, proteomic, and metabolomic approaches is essential to unravel the molecular mechanisms underlying congenital Chagas disease, with a particular focus on the contributions of genetic diversity and non-coding RNAs in immune evasion and disease pathogenesis.

A TaqMan-MGB Probe Quantitative PCR Assay Detecting Hematodinium perezi.

Hematodinium perezi, a pathogenic dinoflagellate, is one of major epidemiological agents that lead to severe losses of cultured marine crustaceans in China. This study aimed to develop a novel, sensitive and specific detection method qualified for early surveillance and control of the disease caused by H. perezi. The present study established a TaqMan-MGB probe quantitative PCR (qPCR) method, targeting the first internal transcribed spacer 1 (ITS 1) region of H. perezi by optimising reaction components. A high correlation coefficient (R2 = 0.9996) was obtained in a standard curve with a 103.4% efficiency. No amplification was observed for the host's genome and pathogens other than H. perezi in the TaqMan-MGB probe qPCR assays, showing high specificity to H. perezi. When using the plasmid standard DNA as templates, the detection limit of the qPCR method was determined to be 5.66 copies/reaction and 10 times more sensitive than the conventional PCR. The TaqMan-MGB probe qPCR assays exhibited high repeatability, and the intra- and inter-assay coefficients of variation (CV) ranged from 0.11% to 2.25% over a wide dynamic range of detection from 5.66 × 100 to 5.66 × 109 copies of targeting gene. The application was also validated on clinical samples, including those with low infection with H. perezi. This novel one-step TaqMan-MGB probe qPCR provides an option for surveillance and epidemiological investigations of H. perezi infection, with an advantage at the early infection stage.

SRNA113 regulates Pseudomonas plecoglossicida motility to affect immune response against infection in pearl gentian grouper.

Small RNAs (sRNAs) are a class of molecules capable of perceiving environmental changes and exerting post-transcriptional regulation over target gene expression, thereby influencing bacterial virulence and host immune responses. Pseudomonas plecoglossicida is a pathogenic bacterium that poses a significant threat to aquatic animal health. However, the regulatory mechanisms of sRNAs in P. plecoglossicida remain unclear. This study focused on sRNA113, previously identified as a potential regulator of the fliP gene, a key component of the lateral flagellar type III secretion system. To investigate the effects of sRNA113 on P. plecoglossicida virulence, as well as its role in regulating pathogenic processes and host immune responses, mutant strains lacking this sRNA were generated and analyzed. Deletion of sRNA113 resulted in the up-regulation of lateral flagellar type III secretion system-related genes in P. plecoglossicida, which enhanced bacterial swarming motility, biofilm formation, and chemotaxis ability in vitro. In vivo infection experiments with pearl gentian grouper revealed that sRNA113 deletion enhanced the pathogenicity of P. plecoglossicida. This heightened virulence was attributed to the up-regulation of genes associated with the lateral flagellar type III secretion system, resulting in higher bacterial loads within host tissues. This amplification of pathogenic activity intensified tissue damage, disrupted immune responses, and impaired the ability of the host to clear infection, ultimately leading to mortality. These findings underscore the critical role of sRNA113 in regulating the virulence of P. plecoglossicida and its interaction with host immune defenses. This study provides a foundation for further exploration of sRNA-mediated mechanisms in bacterial pathogenesis and host-pathogen interactions, contributing to a deeper understanding of virulence regulation and immune evasion in aquatic pathogens.

Use of Tick Cell Lines in Co-Infection Studies with a Preliminary Study of Co-Culture of Borrelia burgdorferi and Anaplasma phagocytophilum.

Ixodes ricinus is an important vector of infectious human and livestock diseases in Europe. Co-infections of pathogens in ticks and hosts have been reported. Tick cell lines offer a useful model system for study of co-infections. We present a review of the existing literature on co-infections in tick cell lines. Previous studies have demonstrated the usefulness of tick cell lines in studies on co-infection of different pathogens and their interaction with the tick microbiome. We also carried out a preliminary study to investigate the effects of co-culturing Borrelia burgdorferi and Anaplasma phagocytophilum on their growth and interactions with the Ixodes ricinus cell line IRE/CTVM19 over a 13-day period. Replication of both pathogens was quantified by real-time PCR. The presence of A. phagocytophilum appeared to have a slight inhibitory effect on the multiplication of B. burgdorferi, that were added subsequently. In contrast, the prior presence of B. burgdorferi appeared to have a stimulatory effect on A. phagocytophilum after 6 days in culture. We conclude that the IRE/CTVM19 tick cell line is suitable for simultaneous and continuous cultivation of both bacteria and can be applied in future research.