Myriam Kratou

Aedes albopictus has recently established self‐sustaining populations in Hungary, but its microbiota—which may influence vector competence—remains poorly understood. We used Oxford Nanopore long‐read sequencing for full‐length 16S rRNA gene profiling of adult Ae. albopictus from two urban sites, Pécs and Barcs. Each location contributed 10 specimens, with contamination controls rigorously applied. Diversity metrics and co‐occurrence network analyses were performed using QIIME2, SparCC, and NetCoMi, with robustness assessed via simulated node removal and addition. Sequencing depth was sufficient to saturate rarefaction curves. Although alpha and beta diversity did not differ significantly between sites, the Pécs population exhibited greater taxonomic richness (100 unique taxa vs. 61 in Barcs) and denser, more clustered networks. Only 15 genera were shared, with Wolbachia dominating both communities. Networks differed in central taxa and structural properties: Pécs retained higher connectivity and shorter paths under perturbation, suggesting greater resilience. Removal of conserved taxa revealed location‐specific impacts on network stability, with Pécs more vulnerable to the loss of key genera. Negative interactions and compensatory taxa emerged post‐removal, indicating distinct reconfiguration strategies. Our findings highlight marked local variation in microbiome structure and robustness, even across a 65‐km gradient. These results establish a high‐resolution baseline for assessing how microbiota shape Ae. albopictus vector potential, informing microbiome‐based control strategies tailored to regional contexts.

Introduction: Ticks and their associated spotted fever group Rickettsia (SFGR) represent an emerging zoonotic risk in Tunisia, where data on tick species distribution and pathogen prevalence remain limited. This study specifically aimed to investigate the diversity and phylogeny of Ixodes and Rhipicephalus tick species and to identify and genetically characterize their associated SFGR species in northwestern Tunisia.Methods: Tick sampling was conducted over a five-month period, from November 2022 to March 2023, in the Jouza district, Beja Governorate, northern Tunisia. A total of 236 ticks were collected both from vegetation using flag-dragging and manually from a red fox (Vulpes vulpes) carcass encountered opportunistically in the field. Tick species were morphologically identified and confirmed by Sanger sequencing of the mitochondrial 16S rRNA gene. Rickettsia detection was performed by nested PCR targeting the ompB gene, followed by species-level identification through sequencing of ompA and gltA partial sequences. Phylogenetic analyses were conducted to assess genetic relationships. Additionally, chi-square tests were used to assess differences in infection rates between tick species, life stages, and collection sources.Results: Ticks belonged to the Ixodes ricinus complex (Ix. ricinus and Ix. inopinatus), Ix. hexagonus, and the Rhipicephalus sanguineus sensu lato complex (Rh. sanguineus sensu strict and Rh. rutilus) have been identified. Twelve and ten genotypes were recorded from 45 and 59 partial 16S rRNA mitochondrial sequences isolated from Ix. ricinus and Ix. inopinatus, respectively. Additionally, one genotype was recorded from five Rh. rutilus specimens, and four genotypes were detected among 23 Rh. sanguineus (temperate lineage) individuals. Overall, 52.1% of ticks tested positive for Rickettsia spp., with significantly higher infection rates in Ix. ricinus (75.6%, p < 0.001) and Ix. inopinatus (67.4%, p < 0.01) compared to the Rhipicephalus group (37.2%) and Ix. hexagonus, which tested negative. Three Rickettsia species were identified: R. monacensis and R. helvetica in the Ix. ricinus complex (including one co-infection), and R. massiliae exclusively in Rhipicephalus ticks. Moreover, phylogenetic analysis revealed that our tick isolates and associated Rickettsia spp. from questing ticks and the red fox clustered primarily with those from other North African and Southern European countries, suggesting trans-Mediterranean strain circulation and a potential link to wildlife reservoirs.Conclusion: These findings enhance our understanding of tick and SFGR diversity in Tunisia and underscores the zoonotic risks from co-circulating Rickettsia species in shared environments. The high infection rates in Ix. ricinus and Ix. inopinatus call for improved national tick surveillance. Public health implications include the need to consider tick-borne rickettsioses in unexplained febrile illness diagnoses. Future studies should assess infection status in hosts, explore seasonal tick dynamics, and evaluate environmental factors affecting Rickettsia transmission.

Tick microbiota influences Borrelia colonization, but changes in the microbiota-derived metabolite and how this affects tick physiology and vector competence is unclear. We investigated whether microbiota-induced metabolite modifications influence tick physiology and pathogen transmission. Using an antimicrobiota vaccine (live Escherichia coli) to immunize mice, we generated host antibodies that modulated the tick microbiome, decreasing bacterial abundance and increasing lysine levels in ticks. Elevated lysine correlated with increased tick weight. Lysine supplementation experiments enhanced defensin expression with DefMT6 exhibiting anti-Borrelia activity, reducing pathogen load in ticks. Our findings demonstrate that antimicrobiota vaccines induce metabolite changes, affecting tick physiology, immunity, and vector competence. These insights open new avenues for developing microbiota-targeted strategies to control tick-borne diseases

Ticks are obligate hematophagous arachnids that play a critical role in transmitting a wide array of pathogens to humans, domestic animals, and wildlife

This study explored the effects of antimicrobiota vaccines on the acquisition of Borrelia and Rickettsia, and on the microbiota composition of Ixodes ricinus ticks. Using a murine model, we investigated the immunological responses to live Staphylococcus epidermidis and multi-antigenic peptide (MAP) vaccines. Immunized mice were infected with either Borrelia afzelii or Rickettsia helvetica, and subsequently infested with pathogen-free I. ricinus nymphs. We monitored the tick feeding behavior, survival rates, and infection levels. Additionally, we employed comprehensive microbiota analyses, including the alpha and beta diversity assessments and microbial co-occurrence network construction. Our results indicate that both live S. epidermidis and MAP vaccines elicited significant antibody responses in mice, with notable bactericidal effects against S. epidermidis. The vaccination altered the feeding patterns and fitness of the ticks, with the Live vaccine group showing a higher weight and faster feeding time. Microbiota analysis revealed significant shifts in the beta diversity between vaccine groups, with distinct microbial networks and taxa abundances observed. Notably, the MAP vaccine group exhibited a more robust and complex network structure, while the Live vaccine group demonstrated resilience to microbial perturbations. However, the effects of antimicrobiota vaccination on Borrelia acquisition appeared taxon-dependent, as inferred from our results and previous findings on microbiota-driven pathogen refractoriness. Staphylococcus-based vaccines altered the microbiota composition but had no effect on B. afzelii infection, and yielded inconclusive results for R. helvetica. In contrast, previous studies suggest that E. coli-based microbiota modulation can induce a pathogen-refractory state, highlighting the importance of both bacterial species and peptide selection in shaping microbiota-driven pathogen susceptibility. However, a direct comparison under identical experimental conditions across multiple taxa is required to confirm this taxon-specific effect. These findings suggest that antimicrobiota vaccination influences tick fitness and microbiota assembly, but its effects on pathogen transmission depend on the bacterial taxon targeted and the selected peptide epitopes. This research provides insights into the need for strategic bacterial taxon selection to enhance vaccine efficacy in controlling tick-borne diseases.

Introduction: The camel-infesting tick, Hyalomma dromedarii, is a prominent ectoparasite in the Middle East and North Africa (MENA) region, critically impacting camel health and acting as a vector for tick-borne pathogens. Despite prior studies on its microbiota, the effects of geographic origin and sex on microbial community structure and functional stability remain poorly understood.Methods: To address this, we characterized the bacterial microbiota of H. dromedarii ticks collected from camels in Tunisia (TUN) and Saudi Arabia (SA) using 16S rRNA gene sequencing, microbial network analysis, and metabolic pathway prediction.Results: Our findings indicate a dominant presence of Francisella endosymbionts in Tunisian ticks, suggesting adaptive roles of H. dromedarii ticks in arid ecosystems. Keystone taxa, particularly Staphylococcus and Corynebacterium, were identified as central to microbial network structure and resilience. Moreover, network robustness analyses demonstrated enhanced ecological stability in the Tunisian tick microbiota under perturbation, indicative of higher resilience to environmental fluctuations compared to Saudi Arabian ticks. Additionally, functional pathway predictions further revealed geographically distinct metabolic profiles between both groups (Tunisia vs. Saudi Arabia and males vs. females), underscoring environmental and biological influences on H. dromedarii microbiota assembly.Discussion: These results highlight region-specific and sex-specific microbial adaptations in H. dromedarii, with potential implications for pathogen transmission dynamics and vector resilience. Understanding these microbial interactions may contribute to improved strategies for tick control and tick-borne disease prevention.

In a recent study, Klink et al