Dynamic nesting of Anaplasma marginale in the microbial communities of Rhipicephalus microplus.

Interactions within the tick microbiome involving symbionts, commensals, and tick-borne pathogens (TBPs) play a pivotal role in disease ecology. This study explored temporal changes in the microbiome of Rhipicephalus microplus, an important cattle tick vector, focusing on its interaction with Anaplasma marginale. To overcome limitations inherent in sampling methods relying on questing ticks, which may not consistently reflect pathogen presence due to variations in exposure to infected hosts in nature, our study focused on ticks fed on chronically infected cattle. This approach ensures continuous pathogen exposure, providing a more comprehensive understanding of the nesting patterns of A. marginale in the R. microplus microbiome. Using next-generation sequencing, microbiome dynamics were characterized over 2 years, revealing significant shifts in diversity, composition, and abundance. Anaplasma marginale exhibited varying associations, with its increased abundance correlating with reduced microbial diversity. Co-occurrence networks demonstrated Anaplasma's evolving role, transitioning from diverse connections to keystone taxa status. An integrative approach involving in silico node removal unveils the impact of Anaplasma on network stability, highlighting its role in conferring robustness to the microbial community. This study provides insights into the intricate interplay between the tick microbiome and A. marginale, shedding light on potential avenues for controlling bovine anaplasmosis through microbiome manipulation.

Real-world evidence of rabies post-exposure prophylaxis in Serbia: Nation-wide observational study (2017-2019).

BACKGROUND: Rabies remains a deadly zoonotic disease, primarily prevalent in Eastern European countries, with a significant global burden in Asia and Africa. Post-exposure prophylaxis (PEP) is critical to prevent clinical rabies. Serbia, a country with a relatively low animal rabies incidence, has been implementing a 4-dose Essen PEP regimen for 13 years. This real-world study aimed to assess the effectiveness of the 4-dose Essen regimen, considering demographic and clinical factors, after WHO Category III exposure. METHOD: The study included 601 patients who received the 4-dose Essen PEP and 79 who received an additional 5th dose. RESULTS: Age emerged as a critical factor influencing seroconversion rates after the 4-dose regimen, with older individuals exhibiting lower RVNA titers. Logistic regression indicated a 3.18% decrease in seroconversion odds for each added year of age. The Cox proportional hazards mixed model highlighted age-related risks, with age groups 45-60 and 75-92 at the highest risk of non-seroconversion. Human Rabies Immune Globulin (HRIG) administration was associated with lower RVNA values after the 4-dose regimen, suggesting interference with vaccine immunogenicity among people who received larger doses of HRIG. CONCLUSIONS: This study provides valuable real-world evidence for rabies PEP in a non-homogeneous population with potential comorbidities. The results underscore the importance of optimizing PEP strategies, particularly in older individuals, and reconsidering HRIG dosing to improve seroconversion rates.

Tick-borne viruses and their risk to public health in the Caribbean: Spotlight on bats as reservoirs in Cuba.

In recent decades, tick-borne diseases (TBDs) have surged and expanded globally due to factors like changes in human activities, land use patterns, and climate change, and it have been associated with the emergence of zoonotic diseases. Cuba faces the impact of ticks on human health and the economy. Although Cuba has studied TBDs extensively for the past 50 years, focus on tick-borne viral pathogens affecting humans remains scant. Despite TBDs not currently being a major health concern in Cuba, factors like inadequate clinician awareness, climate conditions, global tick emergence, and evidence of zoonotic pathogens in ticks underscore the importance of enhanced TBD surveillance in the country. Here we revised the available information on ticks as vectors of pathogenic viruses to humans, spotlighting bats as potential reservoirs of tick-borne viruses (TBVs). Ticks on bats have gained interest as potential reservoirs of pathogenic viruses to humans in Cuba and worldwide. Understanding their role in maintaining viruses and their potential transmission to humans is crucial for the implementation of surveillance and control programs to reduce the risk of tick-borne viral diseases and public health management.

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.

Microfluidic PCR and network analysis reveals complex tick-borne pathogen interactions in the tropics.

BACKGROUND: Ixodid ticks, particularly Rhipicephalus sanguineus s.l., are important vectors of various disease-causing agents in dogs and humans in Cuba. However, our understading of interactions among tick-borne pathogens (TBPs) in infected dogs or the vector R. sanguineus s.l. remains limited. This study integrates microfluidic-based high-throughput real-time PCR data, Yule's Q statistic, and network analysis to elucidate pathogen-pathogen interactions in dogs and ticks in tropical western Cuba. METHODS: A cross-sectional study involving 46 client-owned dogs was conducted. Blood samples were collected from these dogs, and ticks infesting the same dogs were morphologically and molecularly identified. Nucleic acids were extracted from both canine blood and tick samples. Microfluidic-based high-throughput real-time PCR was employed to detect 25 bacterial species, 10 parasite species, 6 bacterial genera, and 4 parasite taxa, as well as to confirm the identity of the collected ticks. Validation was performed through end-point PCR assays and DNA sequencing analysis. Yule's Q statistic and network analysis were used to analyse the associations between different TBP species based on binary presence-absence data. RESULTS: The study revealed a high prevalence of TBPs in both dogs and R. sanguineus s.l., the only tick species found on the dogs. Hepatozoon canis and Ehrlichia canis were among the most common pathogens detected. Co-infections were observed, notably between E. canis and H. canis. Significant correlations were found between the presence of Anaplasma platys and H. canis in both dogs and ticks. A complex co-occurrence network among haemoparasite species was identified, highlighting potential facilitative and inhibitory roles. Notably, H. canis was found as a highly interconnected node, exhibiting significant positive associations with various taxa, including A. platys, and E. canis, suggesting facilitative interactions among these pathogens. Phylogenetic analysis showed genetic diversity in the detected TBPs. CONCLUSIONS: Overall, this research enhances our understanding of TBPs in Cuba, providing insights into their prevalence, associations, and genetic diversity, with implications for disease surveillance and management.

Dissecting the impact of Anaplasma phagocytophilum infection on functional networks and community stability of the tick microbiome.

CONTEXT: Pathogens can manipulate microbial interactions to ensure survival, potentially altering the functional patterns and microbiome assembly. The present study investigates how Anaplasma phagocytophilum infection affects the functional diversity, composition, and assembly of the Ixodes scapularis microbiome, with a focus on high central pathways-those characterized by elevated values in centrality metrics such as eigenvector, betweenness, and degree measures, in the microbial community. METHODS: Using previously published data from nymphs' gut V4 region's amplicons of bacterial 16S rRNA, we predicted the functional diversity and composition in control and A. phagocytophilum-infected ticks and inferred co-occurrence networks of taxa and ubiquitous pathways in each condition to associate the high central pathways to the microbial community assembly. RESULTS: Although no differences were observed concerning pathways richness and diversity, there was a significant impact on taxa and functional assembly when ubiquitous pathways in each condition were filtered. Moreover, a notable shift was observed in the microbiome's high central functions. Specifically, pathways related to the degradation of nucleosides and nucleotides emerged as the most central functions in response to A. phagocytophilum infection. This finding suggests a reconfiguration of functional relationships within the microbial community, potentially influenced by the pathogen's limited metabolic capacity. This limitation implies that the tick microbiome may provide additional metabolic resources to support the pathogen's functional needs. CONCLUSIONS: Understanding the metabolic interactions within the tick microbiome can enhance our knowledge of pathogen colonization mechanisms and uncover new disease control and prevention strategies. For example, certain pathways that were more abundant or highly central during infection may represent potential targets for microbiota-based vaccines.

First molecular characterization of Dirofilaria Immitis in Cuba.

BACKGROUND: Dirofilarioses are widespread diseases caused by mosquito-borne nematodes of the family Onchocercidae, genus Dirofilaria. The major etiologic agent of canine dirofilariosis in the American continent is the zoonotic parasite Dirofilaria immitis. Existing reports of filarioid nematodes in Cuba are based solely on morphological and immunological analysis which do not allow unambiguous identification and/or direct detection of causal agents. RESULTS: Here we present the molecular characterization of filarioid nematodes found in a dog in Cuba. Based on the molecular and phylogenetic analysis of the 5.8S-ITS2-28S region and cox1 gene fragments, the worms were unambiguously classified as D. immitis. Sequence analysis showed high identity of the gene fragments in this study with others previously obtained from D. immitis found in dogs, wolfs and jackals but also from mosquito vectors of D. immitis. CONCLUSIONS: Further studies are guarantee to better understand the epidemiological impact of canine dirofilariosis in Cuba as well as the competence of different species of culicid mosquitoes as vectors of Dirofilaria in the country.

Hierarchical shift of the Aedes albopictus microbiota caused by antimicrobiota vaccine increases fecundity and egg-hatching rate in female mosquitoes.

Recent studies show that mosquito-microbiota interactions affects vector competence and fitness. We investigated if host antibodies modifying microbiota impact mosquito physiology. We focused on three prevalent bacteria (Acinetobacter, Pantoea, and Chryseobacterium), originally isolated from the Asian tiger mosquito Aedes albopictus. Our goal was to assess the impact of host antibodies on mosquito microbiota and life traits. Female mosquitoes were fed with blood from rabbits immunized with each bacterium or a mock vaccine. We compared various factors, including feeding behavior, survival rates, and reproductive success of the mosquitoes. Interestingly, mosquitoes fed with blood from a Chryseobacterium-immunized rabbit showed a significant increase in fecundity and egg-hatching rate. This outcome correlated with a decrease in the abundance of Chryseobacterium within the mosquito microbiota. While no significant changes were observed in the alpha and beta diversity indexes between the groups, our network analyses revealed an important finding. The antimicrobiota vaccines had a considerable impact on the bacterial community assembly. They reduced network robustness, and altered the hierarchical organization of nodes in the networks. Our findings provide the basis for the rational design of antimicrobiota vaccines to reduce mosquito fitness and potentially induce infection-refractory states in the microbiota to block pathogen transmission.

Conserved core microbiota in managed and free-ranging Loxodonta africana elephants.

The gut microbiota plays a crucial role in animal health and homeostasis, particularly in endangered species conservation. This study investigated the fecal microbiota composition of European captive-bred African savanna elephants (Loxodonta africana) housed in French zoos, and compared it with wild African savanna elephants. Fecal samples were collected and processed for DNA extraction and amplicon sequencing of the 16S rRNA gene. The analysis of α and ß diversity revealed significant effects of factors such as diet, daily activity, and institution on microbiota composition. Specifically, provision of branches as part of the diet positively impacted microbiota diversity. Comparative analyses demonstrated distinct differences between captive and wild elephant microbiomes, characterized by lower bacterial diversity and altered co-occurrence patterns in the captive population. Notably, specific taxa were differentially abundant in captive and wild elephants, suggesting the influence of the environment on microbiota composition. Furthermore, the study identified a core association network shared by both captive and wild elephants, emphasizing the importance of certain taxa in maintaining microbial interactions. These findings underscore the impact of environment and husbandry factors on elephant gut microbiota, highlighting the benefits of dietary enrichment strategies in zoos to promote microbiome diversity and health. The study contributes to the broader understanding of host-microbiota interactions and provides insights applicable to conservation medicine and captive animal management.

Transovarial Transmission of Anaplasma marginale in Rhipicephalus (Boophilus) microplus Ticks Results in a Bottleneck for Strain Diversity.

Anaplasma marginale is an obligate intraerythrocytic bacterium of bovines, responsible for large economic losses worldwide. It is mainly transmitted by Rhipicephalus (Boophilus) microplus ticks and, despite mounting evidence suggesting transovarial transmission, the occurrence of this phenomenon remains controversial. We evaluated the vector competence of R. microplus larvae vertically infected with A. marginale to transmit the bacterium to a naïve bovine. A subgroup of engorged female ticks collected from an A. marginale-positive animal was dissected and the presence of the pathogen in its tissues was confirmed. A second subgroup of ticks was placed under controlled conditions for oviposition. After confirming the presence of A. marginale in the hatched larvae, an experimental infestation assay was conducted. Larvae were placed on an A. marginale-free splenectomized calf. The bacterium was detected in the experimentally infested bovine 22 days post-infestation. We analyzed the A. marginale diversity throughout the transmission cycle using the molecular marker MSP1a. Different genotypes were detected in the mammalian and arthropod hosts showing a reduction of strain diversity along the transmission process. Our results demonstrate the vertical transmission of A. marginale from R. microplus females to its larvae, their vector competence to transmit the pathogen, and a bottleneck in A. marginale strain diversity.

Microbiota perturbation by anti-microbiota vaccine reduces the colonization of Borrelia afzelii in Ixodes ricinus.

BACKGROUND: Ticks can transmit a broad variety of pathogens of medical importance, including Borrelia afzelii, the causative agent of Lyme borreliosis in Europe. Tick microbiota is an important factor modulating, not only vector physiology, but also the vector competence. Anti-microbiota vaccines targeting keystone taxa of tick microbiota can alter tick feeding and modulate the taxonomic and functional profiles of bacterial communities in the vector. However, the impact of anti-microbiota vaccine on tick-borne pathogen development within the vector has not been tested. RESULTS: Here, we characterized the Ixodes ricinus microbiota modulation in response to B. afzelii infection and found that the pathogen induces changes in the microbiota composition, its beta diversity and structure of bacterial community assembly. Tick microbiota perturbation by anti-microbiota antibodies or addition of novel commensal bacteria into tick midguts causes departures from the B. afzelii-induced modulation of tick microbiota which resulted in a lower load of the pathogen in I. ricinus. Co-occurrence networks allowed the identification of emergent properties of the bacterial communities which better defined the Borrelia infection-refractory states of the tick microbiota. CONCLUSIONS: These findings suggest that Borrelia is highly sensitive to tick microbiota perturbations and that departure from the modulation induced by the pathogen in the vector microbiota pose a high cost to the spirochete. Network analysis emerges as a suitable tool to identify emergent properties of the vector microbiota associated with infection-refractory states. Anti-microbiota vaccines can be used as a tool for microbiota perturbation and control of important vector-borne pathogens. Video Abstract.

Decontamination protocols affect the internal microbiota of ticks.

Studies on the microbiota of ticks have promoted hypotheses about the combined effects of the bacterial community, its functional contributions to the tick's physiology or probable competition effects with some tick-borne pathogens. However, knowledge on the origin of the microbiota of newly hatched larvae is missing. This study aimed to elucidate the source(s) of the microbiota in unfed tick larvae, addressing the composition of the "core microbiota" and the best ways to decontaminate eggs for microbiota studies. We applied laboratory degree bleach washes and/or ultraviolet light treatments on engorged Rhipicephalus australis females and/or their eggs. No significant effects of these treatments on the reproductive parameters of females and the hatching rates of eggs were observed. However, the different treatments did show striking effects on the composition of the microbiota. The results indicated that bleach washes disrupted the internal tick microbiota in females, implying that bleach may have entered the tick and subsequently affected the microbiota. Furthermore, the analyses of results demonstrated that the ovary is a main source of tick microbiota, while the contribution of Gené's organ (a part of the female reproductive system that secretes a protective wax coat onto tick eggs) or the male's spermatophore requires further investigation. Further studies are needed to identify best practice protocols for the decontamination of ticks for microbiota studies.

Gut microbiota assembly of Gotland varroa-surviving honey bees excludes major viral pathogens.

The spread of the parasite Varroa destructor and associated viruses has resulted in massive honey bee colony losses with considerable economic and ecological impact. The gut microbiota has a major role in shaping honey bees tolerance and resistance to parasite infestation and viral infection, but the contribution of viruses to the assembly of the host microbiota in the context of varroa resistance and susceptibility remains unclear. Here, we used a network approach including viral and bacterial nodes to characterize the impact of five viruses, Apis Rhabdovirus-1 (ARV-1), Black Queen Cell virus (BQCV), Lake Sinai virus (LSV), Sacbrood virus (SBV) and Deformed wing virus (DWV) on the gut microbiota assembly of varroa-susceptible and Gotland varroa-surviving honey bees. We found that microbiota assembly was different in varroa-surviving and varroa-susceptible honey bees with the network of the latter having a whole module not present in the network of the former. Four viruses, ARV-1, BQCV, LSV, and SBV, were tightly associated with bacterial nodes of the core microbiota of varroa-susceptible honey bees, while only two viruses BQCV and LSV, appeared correlated with bacterial nodes in varroa-surviving honey bees. In silico removal of viral nodes caused major re-arrangement of microbial networks with changes in nodes centrality and significant reduction of the networks' robustness in varroa-susceptible, but not in varroa-surviving honey bees. Comparison of predicted functional pathways in bacterial communities using PICRUSt2 showed the superpathway for heme b biosynthesis from uroporphyrinogen-III and a pathway for arginine, proline, and ornithine interconversion as significantly increased in varroa-surviving honey bees. Notably, heme and its reduction products biliverdin and bilirubin have been reported as antiviral agents. These findings show that viral pathogens are differentially nested in the bacterial communities of varroa-surviving and varroa-susceptible honey bees. These results suggest that Gotland honey bees are associated with minimally-assembled and reduced bacterial communities that exclude viral pathogens and are resilient to viral nodes removal, which, together with the production of antiviral compounds, may explain the resiliency of Gotland honey bees to viral infections. In contrast, the intertwined virus-bacterium interactions in varroa-susceptible networks suggest that the complex assembly of microbial communities in this honey bee strain favor viral infections, which may explain viral persistence in this honey bee strain. Further understanding of protective mechanisms mediated by the microbiota could help developing novel ways to control devastating viral infections affecting honey bees worldwide.

Disparate dynamics of pathogen prevalence in Ixodes ricinus and Dermacentor reticulatus ticks occurring sympatrically in diverse habitats.

Ixodes ricinus and Dermacentor reticulatus ticks are important reservoirs and vectors of pathogens. The aim of the present study was to investigate the dynamic of the prevalence and genetic diversity of microorganisms detected in these tick species collected from two ecologically diverse biotopes undergoing disparate long-term climate condition. High-throughput real time PCR confirmed high prevalence of microorganisms detected in sympatrically occurring ticks species. D. reticulatus specimens were the most often infected with Francisella-like endosymbiont (FLE) (up to 100.0%) and Rickettsia spp. (up to 91.7%), while in case of I. ricinus the prevalence of Borreliaceae spirochetes reached up to 25.0%. Moreover, pathogens belonging to genera of Bartonella, Anaplasma, Ehrlichia and Babesia were detected in both tick species regardless the biotope. On the other hand, Neoehrlichia mikurensis was conformed only in I. ricinus in the forest biotope, while genetic material of Theileria spp. was found only in D. reticulatus collected from the meadow. Our study confirmed significant impact of biotope type on prevalence of representatives of Borreliaceae and Rickettsiaceae families. The most common co-infection detected in D. reticulatus was Rickettsia spp. + FLE, while Borreliaceae + R. helvetica was the most common in I. ricinus. Additionally, we found significant genetic diversity of R. raoultii gltA gene across studied years, however such relationship was not observed in ticks from studied biotopes. Our results suggest that ecological type of biotope undergoing disparate long-term climate conditions have an impact on prevalence of tick-borne pathogens in adult D. reticulatus and I. ricinus.

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.

Comparison of salivary gland and midgut microbiome in the soft ticks Ornithodoros erraticus and Ornithodoros moubata.

Introduction: Ornithodoros erraticus and Ornithodoros moubata are the main vectors of African swine fever virus (ASFV) and the human relapsing fever spirochetes Borrelia hispanica and Borrelia crocidurae in the Mediterranean region and Borrelia duttoni in continental Africa. Manipulation of the tick microbiome has been shown to reduce vector fitness and competence in tick vectors, suggesting that the identification of key microbial players associated with tick tissues can inform interventions such as anti-microbiota vaccines to block pathogen development in the midgut and/or salivary glands. Methods: In this study, we analyzed and compared the microbiome of the salivary glands and midgut of O. erraticus and O. moubata. For the taxonomic and functional characterization of the tissue-specific microbiome, we used 16S rRNA amplicon sequencing and prediction of metabolic profiles using PICRUSt2. Co-occurrence networks were built to characterize the community assembly and identify keystone taxa in each tick species. Results: Our results revealed differences in the composition, diversity, and assembly of the bacterial microbiome of salivary glands and midgut within each tick species, but differences were more noticeable in O. moubata. Differences were also found in the microbiome of each tissue, salivary gland and midgut, between species. However, the 'Core Association Networks (CAN)' analysis revealed conserved patterns of interacting taxa in tissues within and between tick species. Different keystone taxa were identified in O. erraticus and O. moubata tissues, but Muribaculaceae and Alistipes were found as keystone taxa in the salivary glands of both tick species which justifies their use as anti-microbiota vaccine candidates to alter the microbiome and reduce tick fitness and/or block pathogen transmission. The high similarity of predicted metabolic pathways profiles between tissues of the two tick species suggests that taxonomic variability of the microbiome is not associated with significant changes in microbial functional profiles. Conclusion: We conclude that the taxonomic structure of the microbiome in O. erraticus and O. moubata is tissue-specific, suggesting niche partitioning of bacterial communities associated to these soft ticks. However, shared keystone taxa and conserved patterns of interacting taxa between tissues and tick species suggest the presence of key microbial players that could be used as anti-microbiota vaccine candidates to affect tick physiology and/or pathogen colonization.

Advances in the Epidemiological Surveillance of Tick-Borne Pathogens.

Ticks are obligate blood-feeding ectoparasites of mammals, birds, and reptiles, which are globally important vectors of pathogens that impact both human and animal health [...].

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.

Avian Malaria Parasites Modulate Gut Microbiome Assembly in Canaries.

Rodent and human malaria parasites cause dysbiosis in the host gut microbiome, but whether Plasmodium species affecting birds cause dysbiosis in their hosts is currently unknown. Here we used a model of avian malaria infection to test whether parasite infection modulates the bird microbiome. To this aim, bird fecal microbiomes were characterized at different time points after infection of canaries with the avian malaria parasite Plasmodium homocircumflexum. Avian malaria caused no significant changes in the alpha and beta diversity of the microbiome in infected birds. In contrast, we discovered changes in the composition and abundance of several taxa. Co-occurrence networks were used to characterize the assembly of the microbiome and trajectories of microbiome structural states progression were found to be different between infected and uninfected birds. Prediction of functional profiles in bacterial communities using PICRUSt2 showed infection by P. homocircumflexum to be associated with the presence of specific degradation and biosynthesis metabolic pathways, which were not found in healthy birds. Some of the metabolic pathways with decreased abundance in the infected group had significant increase in the later stage of infection. The results showed that avian malaria parasites affect bacterial community assembly in the host gut microbiome. Microbiome modulation by malaria parasites could have deleterious consequences for the host bird. Knowing the intricacies of bird-malaria-microbiota interactions may prove helpful in determining key microbial players and informing interventions to improve animal health.