Co-infection dynamics of B. afzelii and TBEV in C3H mice: insights and implications for future research.

Ticks are important vectors of disease, particularly in the context of One Health, where tick-borne diseases (TBDs) are increasingly prevalent worldwide. TBDs often involve co-infections, where multiple pathogens co-exist in a single host. Patients with chronic Lyme disease often have co-infections with other bacteria or parasites. This study aimed to create a co-infection model with Borrelia afzelii and tick-borne encephalitis virus (TBEV) in C3H mice and to evaluate symptoms, mortality, and pathogen level compared to single infections. Successful co-infection of C3H mice with B. afzelii and TBEV was achieved. Outcomes varied, depending on the timing of infection. When TBEV infection followed B. afzelii infection by 9 days, TBEV symptoms worsened and virus levels increased. Conversely, mice infected 21 days apart with TBEV showed milder symptoms and lower mortality. Simultaneous infection resulted in mild symptoms and no deaths. However, our model did not effectively infect ticks with TBEV, possibly due to suboptimal dosing, highlighting the challenges of replicating natural conditions. Understanding the consequences of co-infection is crucial, given the increasing prevalence of TBD. Co-infected individuals may experience exacerbated symptoms, highlighting the need for a comprehensive understanding through refined animal models. This study advances knowledge of TBD and highlights the importance of exploring co-infection dynamics in host-pathogen interactions.

Disruption of bacterial interactions and community assembly in Babesia-infected Haemaphysalis longicornis following antibiotic treatment.

BACKGROUND: A previous study highlighted the role of antibiotic-induced dysbiosis in the tick microbiota, facilitating the transstadial transmission of Babesia microti from nymph to adult in Haemaphysalis longicornis. This study builds on previous findings by analyzing sequence data from an earlier study to investigate bacterial interactions that could be linked to enhanced transstadial transmission of Babesia in ticks. The study employed antibiotic-treated (AT) and control-treated (CT) Haemaphysalis longicornis ticks to investigate shifts in microbial community assembly. Network analysis techniques were utilized to assess bacterial interactions, comparing network centrality measures between AT and CT groups, alongside studying network robustness and connectivity loss. Additionally, functional profiling was conducted to evaluate metabolic diversity in response to antibiotic treatment. RESULTS: The analysis revealed notable changes in microbial community assembly in response to antibiotic treatment. Antibiotic-treated (AT) ticks displayed a greater number of connected nodes but fewer correlations compared to control-treated (CT) ticks, indicating a less interactive yet more connected microbial community. Network centrality measures such as degree, betweenness, closeness, and eigenvector centrality, differed significantly between AT and CT groups, suggesting alterations in local network dynamics due to antibiotic intervention. Coxiella and Acinetobacter exhibited disrupted connectivity and roles, with the former showing reduced interactions in AT group and the latter displaying a loss of connected nodes, emphasizing their crucial roles in microbial network stability. Robustness tests against node removal showed decreased stability in AT networks, particularly under directed attacks, confirming a susceptibility of the microbial community to disturbances. Functional profile analysis further indicated a higher diversity and richness in metabolic capabilities in the AT group, reflecting potential shifts in microbial metabolism as a consequence of antimicrobial treatment. CONCLUSIONS: Our findings support that bacterial interaction traits boosting the transstadial transmission of Babesia could be associated with reduced colonization resistance. The disrupted microbial interactions and decreased network robustness in AT ticks suggest critical vulnerabilities that could be targeted for managing tick-borne diseases.

Microbiota-driven vaccination in soft ticks: Implications for survival, fitness and reproductive capabilities in Ornithodoros moubata.

The Ornithodoros moubata (Om) soft tick, a vector for diseases like tick-borne human relapsing fever and African swine fever, poses challenges to conventional control methods. With diminishing insecticide efficacy, harnessing the tick's microbiota through innovative approaches like microbiota-driven vaccination emerges as a promising strategy for sustainable and targeted disease control. This study investigated the intricate relationship between Pseudomonas, a keystone taxon in the Om microbiome, and its impact on tick fitness, microbiome structure and network dynamics. Utilizing in silico analyses and empirical vaccination experiments, the role of Pseudomonas within microbial networks in the tick midguts (MG) and salivary glands (SG) of Om was studied. Additionally, the consequences of anti-microbiota vaccines targeting Pseudomonas and Lactobacillus on tick fitness, microbiome diversity and community assembly were explored. The result of the study shows that in Om, Pseudomonas plays a central role in microbial networks, influencing keystone species despite being categorized as peripheral (interacting with 47 different taxa, 13 of which are keystone species). Anti-microbiota vaccination targeting Pseudomonas and Lactobacillus yields distinct effects on tick fitness, with Pseudomonas vaccination significantly impacting female tick survival, while Lactobacillus significantly reduced oviposition and fertility. Microbiome changes post-vaccination reveal diversity alterations, emphasizing the impact of vaccine choice. Community assembly dynamics and network robustness analyses highlight Pseudomonas' pivotal role, in influencing topological features and network resilience. The findings of the study provide comprehensive insights into the intricate dynamics of Om microbial networks and the potential of targeted microbiota-driven vaccines for tick control.

Functional redundancy and niche specialization in honeybee and Varroa microbiomes.

The honeybee (Apis mellifera) is a key pollinator critical to global agriculture, facing threats from various stressors, including the ectoparasitic Varroa mite (Varroa destructor). Previous studies have identified shared bacteria between Varroa mites and honeybees, yet it remains unclear if these bacteria assemble similarly in both species. This study builds on existing knowledge by investigating co-occurrence patterns in the microbiomes of both Varroa mites and honeybees, shedding light on potential interactions. Leveraging 16S rRNA datasets, we conducted co-occurrence network analyses, explored Core Association Networks (CAN) and assess network robustness. Comparative network analyses revealed structural differences between honeybee and mite microbiomes, along with shared core features and microbial motifs. The mite network exhibited lower robustness, suggesting less resistance to taxa extension compared to honeybees. Furthermore, analyses of predicted functional profiling and taxa contribution revealed that common central pathways in the metabolic networks have different taxa contributing to Varroa mites and honeybee microbiomes. The results show that while both microbial systems exhibit functional redundancy, in which different taxa contribute to the functional stability and resilience of the ecosystem, there is evidence for niche specialization resulting in unique contributions to specific pathways in each part of this host-parasite system. The specificity of taxa contribution to key pathways offers targeted approaches to Varroa microbiome management and preserving honeybee microbiome. Our findings provide valuable insights into microbial interactions, aiding farmers and beekeepers in maintaining healthy and resilient bee colonies amid increasing Varroa mite infestations.

Structural differences in the gut microbiome of bats using terrestrial vs. aquatic feeding resources.

Bat gut microbiomes are adapted to the specific diets of their hosts. Despite diet variation has been associated with differences in bat microbiome diversity, the influence of diet on microbial community assembly have not been fully elucidated. In the present study, we used available data on bat gut microbiome to characterize the microbial community assembly of five selected bat species (i.e., Miniopterus schreibersii, Myotis capaccinii, Myotis myotis, Myotis pilosus, and Myotis vivesi), using network analysis. These bat species with contrasting habitat and food preferences (i.e., My. capaccinii and My. pilosus can be piscivorous and/or insectivorous; Mi. schreibersii and My. myotis are exclusively insectivorous; while My. vivesi is a marine predator) offer an invaluable opportunity to test the impact of diet on bat gut microbiome assembly. The results showed that My. myotis showed the most complex network, with the highest number of nodes, while My. vivesi has the least complex structured microbiome, with lowest number of nodes in its network. No common nodes were observed in the networks of the five bat species, with My. myotis possessing the highest number of unique nodes. Only three bat species, My. myotis, My. pilosus and My. vivesi, presented a core microbiome and the distribution of local centrality measures of nodes was different in the five networks. Taxa removal followed by measurement of network connectivity revealed that My. myotis had the most robust network, while the network of My. vivesi presented the lowest tolerance to taxa removal. Prediction of metabolic pathways using PICRUSt2 revealed that Mi. schreibersii had significantly higher functional pathway's richness compared to the other bat species. Most of predicted pathways (82%, total 435) were shared between all bat species, while My. capaccinii, My. myotis and My. vivesi, but no Mi. schreibersii or My. pilosus, showed specific pathways. We concluded that despite similar feeding habits, microbial community assembly can differ between bat species. Other factors beyond diet may play a major role in bat microbial community assembly, with host ecology, sociality and overlap in roosts likely providing additional predictors governing gut microbiome of insectivorous bats.

Rickettsial pathogens drive microbiota assembly in Hyalomma marginatum and Rhipicephalus bursa ticks.

Most tick-borne pathogens (TBPs) are secondarily acquired by ticks during feeding on infected hosts, which imposes 'priority effect' constraints, as arrival order influences the establishment of new species in a microbial community. Here we tested whether once acquired, TBPs contribute to bacterial microbiota functioning by increasing community stability. For this, we used Hyalomma marginatum and Rhipicephalus bursa ticks collected from cattle in different locations of Corsica and combined 16S rRNA amplicon sequencing and co-occurrence network analysis, with high-throughput pathogen detection, and in silico removal of nodes to test for impact of rickettsial pathogens on network properties. Despite its low centrality, Rickettsia showed preferential connections in the networks, notably with a keystone taxon in H. marginatum, suggesting facilitation of Rickettsia colonisation by the keystone taxon. In addition, conserved patterns of community assembly in both tick species were affected by Rickettsia removal, suggesting that privileged connections of Rickettsia in the networks make this taxon a driver of community assembly. However, Rickettsia removal had minor impact on the conserved 'core bacterial microbiota' of H. marginatum and R. bursa. Interestingly, networks of the two tick species with Rickettsia have similar node centrality distribution, a property that is lost after Rickettsia removal, suggesting that this taxon drives specific hierarchical interactions between bacterial microbes in the microbiota. The study indicates that tick-borne Rickettsia play a significant role in the tick bacterial microbiota, despite their low centrality. These bacteria are influential and contribute to the conservation of the 'core bacterial microbiota' while also promoting community stability.

Variation of bacterial community assembly over developmental stages and midgut of Dermanyssus gallinae.

Bacterial microbiota play an important role in the fitness of arthropods, but the bacterial microflora in the parasitic mite Dermanyssus gallinae is only partially explored; there are gaps in our understanding of the microbiota localization and in our knowledge of microbial community assembly. In this work, we have visualized, quantified the abundance, and determined the diversity of bacterial occupancy, not only across developmental stages of D. gallinae, but also in the midgut of micro-dissected female D. gallinae mites. We explored community assembly and the presence of keystone taxa, as well as predicted metabolic functions in the microbiome of the mite. The diversity of the microbiota and the complexity of co-occurrence networks decreased with the progression of the life cycle. However, several bacterial taxa were present in all samples examined, indicating a core symbiotic consortium of bacteria. The relatively higher bacterial abundance in adult females, specifically in their midguts, implicates a function linked to the biology of D. gallinae mites. If such an association proves to be important, the bacterial microflora qualifies itself as an acaricidal or vaccine target against this troublesome pest.

Thermostable Keystone Bacteria Maintain the Functional Diversity of the Ixodes scapularis Microbiome Under Heat Stress.

Variations in the composition and diversity of tick microbiome due to high temperatures may influence the hierarchy of community members as a response to environmental change. Modifications in the community structure are hypothesized to drive alterations in the presence and/or abundance of functional pathways in the bacterial metagenome. In this study, this hypothesis was tested by using published 16S rRNA datasets of Ixodes scapularis males incubated at different temperatures (i.e., 4, 20, 30, and 37 °C) in a laboratory setting. Changes in community structure and functional profiles in response to temperature shifts were measured using co-occurrence networks and metagenome inference. Results from laboratory-reared ticks were then compared with those of field-collected ticks. The results from laboratory-reared ticks showed that high temperature altered the structure of the microbial community and decreased the number of keystone taxa. Notably, four taxa were identified as keystone in all the temperatures, and the functional diversity of the tick microbiome was contained in the four thermostable keystone their associated bacterial taxa. Three of the thermostable keystone taxa were also found in free-living ticks collected in Massachusetts. Moreover, the comparison of functional profiles of laboratory-reared and field-collected ticks revealed the existence of an important set of metabolic pathways that were common among the different datasets. Similar to the laboratory-reared ticks, the keystone taxa identified in field-collected ticks alongside their consortia (co-occurring taxa) were sufficient to retain the majority of the metabolic pathways in the functional profile. These results suggest that keystone taxa are essential in the stability and the functional resiliency of the tick microbiome under heat stress.

Exploring the impact of breast cancer on colonization resistance of mouse microbiota using network node manipulation.

Breast cancer, a global health concern affecting women, has been linked to alterations in the gut microbiota, impacting various aspects of human health. This study investigates the interplay between breast cancer and the gut microbiome, particularly focusing on colonization resistance-an essential feature of the microbiota's ability to prevent pathogenic overgrowth. Using a mouse model of breast cancer, we employ diversity analysis, co-occurrence network analysis, and robustness tests to elucidate the impact of breast cancer on microbiome dynamics. Our results reveal that breast cancer exposure affects the bacterial community's composition and structure, with temporal dynamics playing a role. Network analysis demonstrates that breast cancer disrupts microbial interactions and decreases network complexity, potentially compromising colonization resistance. Moreover, network robustness analysis shows the susceptibility of the microbiota to node removal, indicating potential vulnerability to pathogenic colonization. Additionally, predicted metabolic profiling of the microbiome highlights the significance of the enzyme EC 6.2.1.2 - Butyrate--CoA ligase, potentially increasing butyrate, and balancing the reduction of colonization resistance. The identification of Rubrobacter as a key contributor to this enzyme suggests its role in shaping the microbiota's response to breast cancer. This study uncovers the intricate relationship between breast cancer, the gut microbiome, and colonization resistance, providing insights into potential therapeutic strategies and diagnostic approaches for breast cancer patients.

Impact of Plasmodium relictum Infection on the Colonization Resistance of Bird Gut Microbiota: A Preliminary Study.

Avian malaria infection has been known to affect host microbiota, but the impact of Plasmodium infection on the colonization resistance in bird gut microbiota remains unexplored. This study investigated the dynamics of Plasmodium relictum infection in canaries, aiming to explore the hypothesis that microbiota modulation by P. relictum would reduce colonization resistance. Canaries were infected with P. relictum, while a control group was maintained. The results revealed the presence of P. relictum in the blood of all infected canaries. Analysis of the host microbiota showed no significant differences in alpha diversity metrics between infected and control groups. However, significant differences in beta diversity indicated alterations in the microbial taxa composition of infected birds. Differential abundance analysis identified specific taxa with varying prevalence between infected and control groups at different time points. Network analysis demonstrated a decrease in correlations and revealed that P. relictum infection compromised the bird microbiota's ability to resist the removal of taxa but did not affect network robustness with the addition of new nodes. These findings suggest that P. relictum infection reduces gut microbiota stability and has an impact on colonization resistance. Understanding these interactions is crucial for developing strategies to enhance colonization resistance and maintain host health in the face of parasitic infections.