Host Specificity Research Articles

A taxonomic monograph of the Eurasian holoparasitic plant genus Lathraea L. (Orobanchaceae)

A taxonomic monograph is presented for Lathraea L. (Orobanchaceae), a genus of holoparasitic plants distributed across Europe and Asia. Plants in this genus are characterised by their underground stems, achlorophyllous scales with internal gland-lined cavities, and, in some species, explosive seed dehiscence. Despite their conspicuousness, no taxonomic treatment of the genus has been written since 1930. Our work draws upon extensive international field data and a comprehensive survey of herbarium specimens. Detailed descriptions are provided for each species, along with full synonymy, distribution maps, and notes on habitat, host specificity, phenology, ecology, ethnobotany and threat risk. We present evidence to consolidate Lathraea into five species, resolving taxonomic confusion. The infrageneric classification is reviewed and a key to species is provided. Species are illustrated with photographs of living and dried material.

Host genotype and infection status interact to shape microbiomes in Daphnia magna.

Host–bacterial communities (microbiomes) are influenced by a wide range of factors including host genotype and parasite exposure. However, few studies disentangle temporal and host-genotype-specific variation in microbiome response to infection across several host tissues. We experimentally exposed the freshwater crustacean Daphnia magna to its fungal parasite Metschnikowia bicuspidata and characterized changes in host–bacterial communities associated with the parasite's development within the host. We used 16S rRNA gene sequencing to assess bacterial communities of the host (a) 24 h (‘initial parasite exposure’) and (b) 10 days (‘successful infection’) after exposure to a standard dose of M. bicuspidata spores, in host guts, body tissue (excluding guts) and whole individuals. We also investigated whether bacterial community responses to parasite exposure varied by host genotype.Parasite exposure did not immediately alter host gut bacterial communities, but drove host-genotype-specific changes in the bacterial community composition of whole individuals. We validated that these changes were not driven by shifts in bacterial communities of the culturing medium, due to the addition of the parasite spore solution. Successful infection (i.e. the proliferation of M. bicuspidata spores in the host body) reduced alpha diversity and shifted abundance of dominant bacterial orders in the gut. Moreover, it induced a host-genotype-specific changes in body bacterial community composition. Overall, bacterial community responses to parasite exposure and subsequent infection are complex: they occur in a host-genotype-dependent manner, differentially at distinct timepoints after parasite exposure, and in specific host tissue.

Molecular Detection and Genotyping of Chlamydia psittaci in Birds in Buenos Aires City, Argentina

Chlamydia psittaci is a bacterium that infects several species of birds and mammals. It is the causal agent of avian chlamydiosis and psittacosis in humans and it is globally distributed. Chlamydia psittaci is one of the main zoonotic pathogens transmitted by birds. In Argentina, there has been limited research on the prevalence and genetic variability of C. psittaci. The aim of this study was to detect and genotype C. psittaci using molecular techniques in birds living in Buenos Aires City, Argentina, during the period 2012–2015. A descriptive, observational, retrospective and cross-sectional study was carried out. A total of 983 bird samples submitted for diagnosis of avian chlamydiosis were analyzed. The frequency of C. psittaci was 12.54% and 7.89% in Psittaciformes and Columbiformes, respectively. A 348 bp region of the ompA gene was sequenced in positive samples. Molecular genotyping was performed through a Bayesian phylogenetic analysis. Of the 983 bird samples, 83 were positive for C. psittaci and 44 could be sequenced. The genotypes found were A, B, and E. Despite the high levels of host specificity, we found six psittacids with genotype B and one pigeon with genotype A, reflecting the affiliative interaction between Psittaciformes and Columbiformes. This study represents the first survey reporting the presence of C. psittaci in birds within the largest and most populous city in Argentina.

Abstract PR013: Highly accurate detection of early-stage colorectal cancer using tumor and immune extracellular vesicles biomarkers

Abstract Introduction: Colorectal cancer (CRC) is one of the most common cancers worldwide, and early detection is critical for successful treatment and improved survival rates. However, precancerous and early-stage CRC present significant diagnostic challenges due to the small size of lesions and the very low expression of tumor-specific biomarkers in the bloodstream. Current genomics-based diagnostic methods struggle to detect these lesions, making it imperative to develop more sensitive and specific approaches. Circulating extracellular vesicles (EVs) are emerging as a promising solution for early-stage CRC detection, since EVs are produced by tumor cells as well as the tumor microenviroment and host immune cells. Thus, EVs may offer the means to detect and monitor small early-stage tumors through both direct detection of tumor- associated biomarkers as well through tumor specific host response and tumor microenvironment biomarkers. Methods: To identify novel early-stage CRC specific biomarkers, we performed proteomics analysis on EVs purified from patient plasma using size exclusion chromatography and a proprietary buffer system that enhances EV and corona protein recovery. TrueDiscovery™ Data-independent acquisition (DIA) mass spectrometry (MS) analysis was conducted on 24 pre- cancer/stage 0 and 25 stage 1 CRC patients and 75 normal patient plasma samples. An in-house developed machine learning pipeline was used to identify differentially expressed proteins and model candidate multiplexes to identify those with extremely high diagnostic accuracy (> 0.99). Results: An average of ∼2,500 proteins were identified per sample and included in bioinformatics analysis. Comparative analysis between control patient EVs and either pre- cancerous/Stage 0, or Stage 1 colon cancer EVs using an in-house Machine Learning pipeline identified 336 and 493 differentially expressed proteins for each group (FDR adjusted p-value < 0.001). Of these, the best 17 pre/stage 0 proteins and 53 stage 1 proteins were trained and tested using Support Vector Machine to assess all potential 3-plexes in order to identify those with mean diagnostic accuracy > 99%. This yielded 5 3-plexes in precancer/stage 0 and 34 3-plexes in stage 1 with near perfect diagnostic accuracy. These plexes are currently being assessed in single analyte and multiplex immunoassays with the goal of translating candidate 3-plexes to the clinical. Conclusions: Key biomarkers from CRC patient EVs indicate the potential to detect and diagnose early-stage and low tumor burden cancers using our methods. Interestingly, the most accurate 3-plexes consist of proteins from immune, inflammatory and metabolic processes, suggesting that for the detection of early stage cancer it may be critical to include both tumor and host specific biomarkers. Citation Format: Poorva Mudgal, Cheryl Bandoski, Zachary Opheim, Martin Mehnert, Valesca Anschau, Issa Isaac, Alan Ezrin, Todd Hembrough. Highly accurate detection of early-stage colorectal cancer using tumor and immune extracellular vesicles biomarkers [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr PR013.

Comprehensive pan-genome analysis of Mycobacterium marinum: insights into genomic diversity, evolution, and pathogenicity.

Mycobacteria is a diverse genus that includes both innocuous environmental species and serious pathogens like Mycobacterium tuberculosis, Mycobacterium leprae, and Mycobacterium ulcerans, the causative agents of tuberculosis, leprosy, and Buruli ulcer, respectively. This study focuses on Mycobacterium marinum, a closely related species known for its larger genome and ability to infect ectothermic species and cooler human extremities. Utilizing whole-genome sequencing, we conducted a comprehensive pan-genome analysis of 100M. marinum strains, exploring genetic diversity and its impact on pathogenesis and host specificity. Our findings highlight significant genomic diversity, with clear distinctions in core, dispensable, and unique genes among the isolates. Phylogenetic analysis revealed a broad distribution of genetic lineages, challenging previous classifications into distinct clusters. Additionally, we examined the synteny and diversity of the virulence factor CpnT, noting a wide range of C-terminal domain variations across strains, which points to potential adaptations in pathogenic mechanisms. This study enhances our understanding of M. marinum's genomic architecture and its evolutionary relationship with other mycobacterial pathogens, providing insights that could inform disease control strategies for M. tuberculosis and other mycobacteria.

What, how, and why? - anti-EHEC phages and their application potential in medicine and food industry.

Enterohemorrhagic Escherichia coli (EHEC) are pathogens that, only in the United States, cause more than 250,000 foodborne infections a year. Since antibiotics or other antidiarrheal agents may increase the hemolytic-uremic syndrome (HUS) development risk, currently only supportive therapy, including hydration, is used. Therefore, many methods to fight EHEC bacteria focus on their use in food processing to prevent human infection. One of the proposed anti-EHEC agents is bacteriophages, known for their bactericidal effect, host specificity, and lack of cross-resistance with antibiotics. In this review article, we provide an overview of the characteristics like source of isolation, morphology, kinetics of life cycle, and treatment potential of over 130 bacteriophages able to infect EHEC strains. Based on the reviewed literature, we conclude that bacteriophages may play a highly significant role in regulating EHEC propagation. In addition, we also point out the phage features that should be taken into account not only when using bacteriophages but also when examining their properties. This may contribute to accelerating the pace of work on the preventive use of bacteriophages, which is extremely needed in the modern world of the food industry, but also stimulate interest in phages and accelerate regulatory work that would enable the use of bacteriophages also in medicine, to fight the drug-resistant strains.

The Plasmodium transmission-blocking symbiont, Microsporidia MB, is vertically transmitted through Anopheles arabiensis germline stem cells.

Microsporidia MB is a promising candidate for developing a symbiont-based strategy for malaria control because it disrupts the capacity of An. arabiensis to transmit the Plasmodium parasite. The symbiont is predominantly localized in the reproductive organs and is transmitted vertically from mother to offspring and horizontally (sexually) during mating. Due to the contribution of both transmission routes, Microsporidia MB has the potential to spread through target vector populations and become established at high prevalence. Stable and efficient vertical transmission of Microsporidia MB is important for its sustainable use for malaria control, however, the vertical transmission efficiency of Microsporidia MB can vary. In this study, we investigate the mechanistic basis of Microsporidia MB vertical transmission in An. arabiensis. We show that vertical transmission occurs through the acquisition of Microsporidia MB by Anopheles cystocyte progenitors following the division of germline stem cells. We also show that Microsporidia MB replicates to increase infection intensity in the oocyte of developing eggs when mosquitoes take a blood meal suggesting that symbiont proliferation in the ovary is coordinated with egg development. The rate of Microsporidia MB transmission to developing eggs is on average higher than the recorded (mother to adult offspring) vertical transmission rate. This likely indicates that a significant proportion of An. arabiensis offspring lose their Microsporidia MB symbionts during development. The stability of germline stem cell infections, coordination of symbiont proliferation, and very high rate of transmission from germline stem cells to developing eggs indicate that Microsporidia MB has a highly specialized vertical transmission strategy in An. arabiensis, which may explain host specificity.

Characterization, Genome Sequencing, and Development of a Rapid PCR Identification Primer for Fusarium oxysporum f. sp. crocus, a New forma specialis Causing Saffron Corm Rot

Saffron corm rot (SCR), the most serious disease affecting saffron, has been confirmed to be caused by Fusarium oxysporum in previous studies. Compared to other fungal species, F. oxysporum exhibits host specialization, a special phenomenon associated with the secreted in xylem (SIX) genes. This study examined the pathogenicity specialization of F. oxysporum isolated from saffron corms with SCR disease. The results showed that this F. oxysporum strain was strongly pathogenic to saffron corms, causing SCR; weakly pathogenic to the corms of freesia, which is in the Iridaceae family along with saffron; and not pathogenic to watermelon, melon, and tomato. Other formae speciales of F. oxysporum were not pathogenic to saffron corms. This suggests that F. oxysporum saffron strains exhibit obvious pathogenicity specialization for Iridaceae spp. Subsequently, the F. oxysporum saffron strain (XHH35) genome was sequenced, and a comparative genomics study of XHH35 and three other formae speciales was conducted using OrthoVenn3. XHH35 contained 90 specific genes absent in the other three formae speciales. These genes are involved in certain key biological processes and molecular functions. Based on BLAST homology searching, the F. oxysporum saffron strain (XHH35) genome was predicted to contain seven SIX genes (SIX 4, SIX 6, SIX 7, SIX 10, SIX 11, SIX 12, and SIX 14) highly homologous to F. oxysporum f. sp. lycopersici, which was verified using polymerase chain reaction (PCR) amplification. The corresponding individual phylogenetic tree indicated that the F. oxysporum saffron strain (XHH35) showed a separate branch with different formae speciales. This study is the first-ever report of F. oxysporum f. sp. crocus, a new forma specialis. Based on the specificity of its SIX genes, the SIX 10 gene was selected to further establish a rapid identification technique for F. oxysporum f. sp. crocus, which will be useful in future research.

Transcriptomic responses of Solanum tuberosum cv. Pirol to arbuscular mycorrhiza and potato virus Y (PVY) infection.

Arbuscular mycorrhizal fungi (AMF) serve as both plant symbionts and allies in resisting pathogens and environmental stresses. Mycorrhizal colonization of plant roots can influence the outcomes of plant-pathogen interactions by enhancing specific host defense mechanisms. The transcriptional responses induced by AMF in virus-infected plants remain largely unexplored. In the presented study, we employed a comprehensive transcriptomic approach and qPCR to investigate the molecular determinants underlying the interaction between AMF and potato virus Y (PVY) in Solanum tuberosum L. Our primary goal was to identify the symbiosis- and defense-related determinants activated in mycorrhizal potatoes facing PVY. Through a comparative analysis of mRNA transcriptomes in experimental treatments comprising healthy and PVY-infected potatoes colonized by two AMF species, Rhizophagus regularis or Funneliformis mosseae, we unveiled the overexpression of genes associated with mycorrhiza, including nutrient exchange, lipid transfer, and cell wall remodeling. Furthermore, we identified several differentially expressed genes upregulated in all mycorrhizal treatments that encoded pathogenesis-related proteins involved in plant immune responses, thus verifying the bioprotective role of AMF. We investigated the relationship between mycorrhiza levels and PVY levels in potato leaves and roots. We found accumulation of the virus in the leaves of mycorrhizal plants, but our studies additionally showed a reduced PVY content in potato roots colonized by AMF, which has not been previously demonstrated. Furthermore, we observed that a virus-dependent reduction in nutrient exchange could occur in mycorrhizal roots in the presence of PVY. These findings provide an insights into the interplay between virus and AMF.

Unsupervised learning analysis on the proteomes of Zika virus

Background The Zika virus (ZIKV), which is transmitted by mosquito vectors to nonhuman primates and humans, causes devastating outbreaks in the poorest tropical regions of the world. Molecular epidemiology, supported by clustering phylogenetic gold standard studies using sequence data, has provided valuable information for tracking and controlling the spread of ZIKV. Unsupervised learning (UL), a form of machine learning algorithm, can be applied on the datasets without the need of known information for training. Methods In this work, unsupervised Random Forest (URF), followed by the application of dimensional reduction algorithms such as principal component analysis (PCA), Uniform Manifold Approximation and Projection (UMAP), t-distributed stochastic neighbor embedding (t-SNE), and autoencoders were used to uncover hidden patterns from polymorphic amino acid sites extracted on the proteome ZIKV multi-alignments, without the need of an underlying evolutionary model. Results The four UL algorithms revealed specific host and geographical clustering patterns for ZIKV. Among the four dimensionality reduction (DR) algorithms, the performance was better for UMAP. The four algorithms allowed the identification of imported viruses for specific geographical clusters. The UL dimension coordinates showed a significant correlation with phylogenetic tree branch lengths and significant phylogenetic dependence in Abouheif’s Cmean and Pagel’s Lambda tests (p value < 0.01) that showed comparable performance with the phylogenetic method. This analytical strategy was generalizable to an external large dengue type 2 dataset. Conclusion These UL algorithms could be practical evolutionary analytical techniques to track the dispersal of viral pathogens.

Analyses of the gut microbial composition of domestic pig louse Haematopinus suis

Haematopinus suis is an obligatory ectoparasite of the domestic pig, serving as a vector of several swine pathogens and posing great threats to the pig industry. The gut microbiome of lice is thought of an important mediator of their healthy physiology. However, there is a great paucity of lice-associated microbial communities’ structure and function. The current study aimed to profile the gut microbiome and to understand the microbial functions of swine lice by metagenomic sequencing and bioinformatics analyses. In total, 102,358 (77.2 %) nonredundant genes were cataloged, by contrast, only a small proportion of genes were assigned to microbial taxa and functional assemblages. Bacteria of known or potential public health significance such as Anaplasma phagocytophilum, Chlamydia trachomatis, Waddlia chondrophila, Bacillus cereus, and Leptotrichia goodfellowii were observed in all samples. The integrated microbial profile further illustrated the evolutionary relevance of endosymbionts and detailed the functional composition, and findings suggested H. suis may acquire adenosylcobalamin by feeding due to an adenosylcobalamin synthesis defect and a lack of complete synthases of endosymbionts. Sucking lice contained fewer functional genes compared with ticks and fleas probably because of the obligate host specificity of parasitic lice. In addition, the genes from the intestines contained encompassed most of the microbial functional genes in sucking lice. A wide range of unknown taxonomic and functional assemblages were discovered, which improves our understanding related to microbial features and physiological activities of sucking lice. In general, this study increases the characterization of the microbiota of lice and offers clues for preventing and controlling lice infestation in swine production in the future.

Adaptation of Candida albicans to specific host environments by gain-of-function mutations in transcription factors.

The yeast Candida albicans is usually a harmless member of the normal microbiota in healthy persons but is also a major fungal pathogen that can colonize and infect almost every human tissue. A successful adaptation to environmental changes encountered in different host niches requires an appropriate regulation of gene expression. The zinc cluster transcription factors are the largest family of transcriptional regulators in C. albicans and are involved in the control of virtually all aspects of its biology. Under certain circumstances, mutations in these transcription factors that alter their activity and the expression of their target genes confer a selective advantage, which results in the emergence of phenotypically altered variants that are better adapted to new environmental challenges. This review describes how gain-of-function mutations in different zinc cluster transcription factors enable C. albicans to overcome antifungal therapy and to successfully establish itself in specific host niches.

Species Diversity, Host Association, and Evolutionary History of Cronartium: An Important Global Fungal Pathogen to Trees.

Pine stem rust, the most damaging and widespread forest disease occurring in pine trees in the Northern Hemisphere, is primarily caused by Cronartium species (Pucciniales, Melampsorineae). While the phylogenetic relationships of major Cronartium species have been largely elucidated, there is limited understanding of their species diversity and the evolutionary processes shaping their distribution patterns. In this work, we performed broad sampling and sequencing of Cronartium taxa in China together with additional sequence data and other accessions in NCBI to investigate the diversification and to estimate the divergence time of major evolutionary events in this genus. Molecular dating analysis suggested that the divergence of the genus Cronartium probably was around 91.78 Ma during the Upper Cretaceous. It is believed that Cronartium species may have originated in Asia and North America, with intercontinental dispersals occurring primarily during the Middle Eocene, Middle Miocene, and Pliocene. These dispersal events likely took place through the North Atlantic Land Bridge, the De Geer Route, and the Bering Land Bridge, and subsequently diverged through sporadic dispersal and vicariance events. Furthermore, our analysis of host associations revealed that the diversification of Cronartium species was correlated with their telial-hosts, and some species may have experienced host jump events, indicating a complex interplay between host specificity and pathogen-host interaction during Cronartium evolution.

Erysipelothrix rhusiopathiae-associated bloodstream infection in a patient with systemic lupus erythematosus: a case report and literature review

Introduction. Systemic human infections caused by Erysipelothrix rhusiopathiae have been increasingly reported especially within immunocompromised hosts and those with significant occupational exposure to livestock and aquatic animals. We report a case of E. rhusiopathiae bacteraemia in a patient with systemic lupus erythematosus (SLE) and present a literature review on clinical outcomes and microbiologic diagnosis for this organism. Case presentation. A 43-year-old female patient was reporting a 1-month history of intermittent fevers. She recently increased her immunosuppression medication for her underlying SLE on the advice of her rheumatologist. The patient sustained a finger laceration from butchering cattle meat 2 weeks after the onset of her initial symptoms, with worsening index finger swelling and increased febrile episodes. Two weeks post-injury, multiple blood cultures were drawn, and each isolated Gram-positive bacilli. Given her recurrent intermittent fevers, there was a concern for ongoing infection, and therefore, intravenous vancomycin was started with prompt referral to an outpatient parenteral antibiotic therapy clinic. The Gram-positive bacillus was confirmed as E. rhusiopathiae via matrix-assisted laser desorption/ionization-time of flight analysis. Given intrinsic resistance to vancomycin, vancomycin was switched to intravenous ceftriaxone as targeted antimicrobial therapy for 2 weeks. Reassuringly, there was no echocardiographic evidence of infective endocarditis, warranting the prolonged treatment course. Post-treatment, she remained symptom-free with the resolution of joint symptoms and fevers. Conclusion. Our report illustrates a case of E. rhusiopathiae bacteraemia from an immunodeficient host, with prompt microbiologic diagnosis and intervention with appropriate antimicrobial coverage. Literature reflects the rarity of this infection, predilections to specific susceptible hosts and the importance of raising awareness of zoonotic infections.

Representative honey bee viruses do not replicate in the small hive beetle, Aethina tumida Murray

The small hive beetle (SHB), Aethina tumida Murray, is an invasive pest of the honey bee and causes significant damage through the consumption of colony resources and brood. Two assumptions related to honey bee virus transmission have been made about SHB: first, that SHB vectors honey bee viruses and second, that these viruses replicate in SHB based on the detection of both positive and negative strand viral genomic RNA within SHB. To clarify the role of SHB in virus transmission, we sought to address whether selected honey bee viruses replicate in SHB. Sequences derived from five honey bee viruses were identified in the transcriptomes of field-caught SHB from the U.S., but not in those of lab-reared SHB, suggesting that these viruses do not replicate in SHB. To elucidate whether the representative viruses, Israeli acute paralysis virus (IAPV; Dicistroviridae) and Deformed wing virus (DWV; Iflaviridae) replicate in SHB, we tested for replication in vitro in an SHB-derived cell line (BCIRL-AtumEN-1129-D6). Following treatment of the cell line with viral particles or viral RNA, the number of virus genomes was monitored by reverse transcription quantitative PCR (RT-qPCR). In contrast to the positive control, IAPV and DWV RNA levels steadily decreased over a period of 8 days. Collectively, these results from bioinformatic observations and in vitro experiments indicate that IAPV and DWV do not replicate in SHB. These results are consistent with the host specificity of most insect viruses within a single insect order and indicate that while SHB may serve as a mechanical vector of honey bee viruses within and between hives, this insect does not serve as a biological vector for these honey bee viruses.

Thermally stable Al4B2O9:Ce3+ nanofibers with intense blue emission and Al4B2O9:Ce3+/Dy3+ nanofibers with color-tunable luminescence and white-light emission via energy transfer

Dy3+ can achieve white-light emission at the appropriate intensity ratio of yellow to blue light in specific hosts due to its wide yellow and blue emitting bands. However, luminescence intensity of singly doped Dy3+ in the matrix is low, which limits its application in PC-WLEDs. Al4B2O9 has become a promising rare earth ion-doped matrix owing to its ease of doping, low price, excellent chemical and thermal stability. In this work, to improve the Dy3+ emission intensity and to achieve color-tunable luminescence and white-light emission, with the help of energy level matching engineering, Ce3+ ions with a strong and broad absorption band and suitable energy levels matching with Dy3+ are selected as high-efficient sensitizers. Ce3+ doped and Ce3+/Dy3+ co-doped one-dimensional (1D) Al4B2O9 nanofibers are designed and successfully synthesized using a simple electrospinning coupled with an oxidative calcination. Under the excitation of 286-nm UV light, Al4B2O9:Ce3+ nanofibers emit intense blue light and can be used as blue-emitting phosphor, and the emission peak of Al4B2O9:Ce3+/Dy3+ nanofibers at 374 nm is attributed to the 5d→2F5/2 energy level transition of Ce3+, and emission peaks at 483 and 575 nm are ascribed to the 4F9/2→6H15/2, 13/2 energy level transitions of Dy3+, respectively. By modulating the doping concentration of Dy3+ and Ce3+→Dy3+ energy transfer (ET) process, color-tunable luminescence and white-light emission are resoundingly realized to address the weak luminescence intensity of Dy3+. In addition, Al4B2O9:Ce3+/Dy3+ nanofibers have excellent thermal stability. The formation mechanism and luminescence mechanism of Al4B2O9:Ce3+/Dy3+ nanofibers are presented, and the Ce3+→Dy3+ ET mechanism in Al4B2O9:Ce3+/Dy3+ nanofibers is elucidated. The designing concept and the technology in this work are instructive for preparing new phosphors with 1D morphology and super fluorescence.

Proteomic identification of apoplastic proteins from rice, wheat, and barley after Magnaporthe oryzae infection

The fungal pathogen Magnaporthe oryzae causes devastating blast disease in various cereals, including rice (Oryza sativa), wheat (Triticum aestivum), maize (Zea mays), and barley (Hordeum vulgare). Despite previous reports on fungal host specificity, the mechanisms underlying differential host infection strategies remain unclear. This study aimed to identify differentially abundant proteins (DAPs) in the apoplast of rice, barley, and wheat following infection with two M. oryzae pathovars using liquid chromatography-tandem mass spectrometry (LC–MS/MS). LC–MS/MS analysis revealed an enrichment of both M. oryzae and host proteins in the apoplast during the compatible reaction compared to the incompatible reaction. DAPs from M. oryzae involved in the host interaction included secreted extracellular enzymes (e.g., hydrolases), which were significantly increased in the M. oryzae Oryzae (MoO)-infected rice apoplast. Among host proteins, the proportion of protein-modifying enzymes increased in the M. oryzae Triticum (MoT)-infected rice and MoO-infected wheat apoplastic fluids, particularly rice glycosidases, peroxidases, and serine proteases, as well as wheat serine proteases. Furthermore, DAPs from MoL-infected rice were enriched in carbohydrate metabolism, suggesting that carbohydrate metabolism-related proteins may play a vital role in rice resistance to MoL. Additionally, protein-modifying and cytoskeletal proteins, as well as stress-responsive proteins, were enriched in the MoO-infected wheat apoplastic fluid. Finally, DAPs from both MoO- and MoL-infected barley were enriched in hydrogen peroxide catabolism, suggesting that peroxidases may be vital for barley resistance to M. oryzae. The identification of DAPs from both M. oryzae strains and the three host plants offers valuable insights into the host specificity mechanisms of M. oryzae in cereal crops.

Virulence, multiple drug resistance, and biofilm-formation in Salmonella species isolated from layer, broiler, and dual-purpose indigenous chickens.

Globally, the significant risk to food safety and public health posed by antimicrobial-resistant foodborne Salmonella pathogens is driven by the utilization of in-feed antibiotics, with variations in usage across poultry production systems. The current study investigated the occurrence of virulence, antimicrobial resistant profiles, and biofilm-forming potentials of Salmonella isolates sourced from different chicken types. A total of 75 cloacal faecal samples were collected using sterile swabs from layer, broiler, and indigenous chickens across 15 poultry farms (five farms per chicken type). The samples were analysed for the presence of Salmonella spp. using species-specific PCR analysis. Out of the 150 presumptive isolates, a large proportion (82; 55%) were confirmed as Salmonella species, comprising the serovars S. typhimurium (49%) and S. enteritidis (30%) while 21% were uncategorised. Based on phenotypic antibiotic susceptibility test, the Salmonella isolates were most often resistant to erythromycin (62%), tetracycline (59%), and trimethoprim (32%). The dominant multiple antibiotic resistance phenotypes were SXT-W-TE (16%), E-W-TE (10%), AML-E-TE (10%), E-SXT-W-TE (13%), and AMP-AML-E-SXT-W-TE (10%). Genotypic assessment of antibiotic resistance genes revealed that isolates harboured the ant (52%), tet (A) (46%), sui1 (13%), sui2 (14%), and tet (B) (9%) determinants. Major virulence genes comprising the invasion gene spiC, the SPI-3 encoded protein (misL) that is associated with the establishment of chronic infections and host specificity as well as the SPI-4 encoded orfL that facilitates adhesion, autotransportation and colonisation were detected in 26%, 16%, and 14% of the isolates respectively. There was no significant difference on the proportion of Salmonella species and the occurrence of virulence and antimicrobial resistance determinants among Salmonella isolates obtained from different chicken types. In addition, neither the chicken type nor incubation temperature influenced the potential of the Salmonella isolates to form biofilms, although a large proportion (62%) exhibited weak to strong biofilm-forming potentials. Moderate to high proportions of antimicrobial resistant pathogenic Salmonella serovars were detected in the study but these did not vary with poultry production systems.

Myrmozercon mites are highly host specific: two new species of Myrmozercon Berlese associated with sympatric Camponotus ants in southern Quintana Roo, Mexico.

Two new species of Myrmozercon, M. serratus sp. nov. and M. spatulatus sp. nov., are described based on adults and deutonymphs collected in association with ants in Mexico. They represent the first records of this genus from the Neotropic s.s. faunal region. Both new species are associated with hosts in the genus Camponotus from the same small area of a coastal lagoon, which share the same nesting habit preferences, providing strong evidence for host specificity. All but one colony of C. atriceps hosted mites, whereas they occurred in only half of the colonies of C. rectangularis. There was a significant positive correlation between the abundance of C. atriceps sexual ants and the abundance of mites. We summarize the known host associations for the genus Myrmozercon and discuss host specificity. Larvae of both mite species were collected on the wings of males and gynes suggesting that egg laying occurs on the hosts reproductive caste. Two hypotheses explaining this observation are discussed, larvae may be phoretic on winged sexuals, favoring mite co-dispersal with hosts, or larvae reside on the alates as a refuge from predation.

Genetic diversity of Bartonella species in small mammals in the Qinghai Menyuan section of Qilian Mountain National Park, China

Bartonella are vector-borne gram-negative facultative intracellular bacteria that can infect a wide spectrum of mammals, and are recognized as emerging human pathogens. This study aimed to investigate the prevalence and molecular characteristics of Bartonella infections in small mammals within the Qinghai Menyuan section of Qilian Mountain National Park, China. Small mammals were captured, and the liver, spleen and kidney were collected for Bartonella detection and identification using a combination of real-time PCR targeting the transfer-mRNA (ssrA) gene and followed by sequencing of the citrate synthase (gltA) gene. A total of 52 rodents were captured, and 36 rodents were positive for Bartonella, with a positivity rate of 69.23% (36/52). Bartonella was detected in Cricetulus longicaudatus, Microtus oeconomus, Mus musculus, and Ochotona cansus. The positivity rate was significantly different in the different habitats. Two Bartonella species were observed, including Bartonella grahamii and Bartonella heixiaziensis, and B. grahamii was the dominant epidemic strain in this area. Phylogenetic analysis showed that B. grahamii mainly clustered into two clusters, which were closely related to the Apodemus isolates from China and Japan and the local plateau pika isolates, respectively. In addition, genetic polymorphism analysis showed that B. grahamii had high genetic diversity, and its haplotype had certain regional differences and host specificity. Overall, high prevalence of Bartonella in small mammals in the Qinghai Menyuan section of Qilian Mountain National Park. B. grahamii is the dominant strain with high genetic diversity and potential pathogenicity to humans, and corresponding control measures should be considered.