Vector-borne infectious diseases (2)T-cell and B-cell Immunology (1)Gut microbiota and health (1)Streptococcal Infections and Treatments (1)Invertebrate Immune Response Mechanisms (1)
Jakimovski D, Banović P, Mateska S, Stavrova M, Stamenkovska A, et al.
Ticks and tick-borne diseases •
Ticks and tick-borne pathogens (TBPs) pose an expanding health threat across Europe, yet few studies link tick infection data directly to human clinical outcomes. We conducted a prospective, cross-border "One Health" study in Serbia and North Macedonia to assess the prevalence, diversity, and potential transmission of TBPs from ticks to humans. A total of 133 tick-infested patients were enrolled at two healthcare centers (112 in Skopje, 26 in Novi Sad), and 135 ticks were collected from these individuals, alongside paired blood and serum samples. Overall, TBP DNA was detected in 66.6 % of ticks, with Rickettsia helvetica (25.9 %) and Rickettsia monacensis (12.5 %) were most common. Mixed infections occurred in 15 % of ticks, with up to three pathogens co-occurring. Other detected TBPs included Borrelia afzelii, Borrelia garinii, Borrelia lusitaniae, Anaplasma phagocytophilum, Babesia microti, and Babesia divergens. Four patients (3 %) had detectable pathogen DNA in blood, primarily Rickettsia spp. and Anaplasma spp., yet remained asymptomatic. Most common clinical outcome during the observation period was local hypersensitivity reaction (21.1 %), while α-Gal sensitization was detected in two cases. Phylogenetic analysis revealed Balkan Rickettsia and Borrelia strains were mostly identical to Western and Central European lineages, with a notable exception: a Bo. garinii strain from North Macedonia clustered with strains from Russia and China, indicating possible long-distance introduction. The present study demonstrates that human exposure to multiple TBPs is common and while asymptomatic bloodstream infections do occur, local hypersensitivity reactions are much more common.
Mateos-Hernandez L, Wu-Chuang A, Maitre A, Rego ROM, Abuin-Denis L, et al.
Ticks and tick-borne diseases •
The gut microbiome undergoes natural selection pressure, likely because it can affect infection resistance by stimulating natural antibody (NAb) production, notably against the glycan Galα1-3Galβ1-4GlcNAc-R (α-Gal). In our study, we explored whether particular glycans, such as α-Gal, from specific host microbiota components could trigger NAbs that, once ingested by Ixodes ricinus ticks during the blood meal, are capable of cross-reacting with bacterial strains in the tick microbiota that share these glycans. Such interactions might alter the tick microbiota and reduce Borrelia afzelii colonization in ticks. When mice were orally administered various Escherichia coli strains, it triggered the stimulation of NAbs and resulted in strain-specific alterations in the tick microbiota. These changes effectively decreased Borrelia colonization in the tick vector. Additionally, vaccination with the glycan α-Gal induced notable shifts in the tick microbiota and similarly reduced Borrelia colonization. Reduced Borrelia colonization was associated with shifts in bacterial diversity, abundance, and microbial network properties. The study provides evidence that natural mechanisms, such as the production of NAb in response to the host gut microbiome, can modulate the microbiota of disease vectors and reduce pathogen colonization within the vector. These findings offer new insights into potential strategies for reducing the transmission of vector-borne diseases through modulation of the host gut microbiome.
Thorel M, Mateos-Hernandez L, Mulot B, Azzouni MN, Hodžić A, et al.
Frontiers in immunology •
Aspergillosis is a fungal infection caused mainly by that often results in respiratory disease in birds. Aspergillosis is a major cause of morbidity and mortality in captive-bred penguin species. Currently, there is no registered vaccine to prevent aspergillosis. Recent research demonstrated that oral administration of gram-negative bacteria expressing high levels of galactose-α-1,3-galactose (α-Gal) modulates anti-α-Gal immunity and protects turkeys from clinical aspergillosis caused by experimental infection. The role of anti-α-Gal immunity in penguins has not been studied. Here, we tested the distribution of α-1,3-galactosyltransferase (α1,3GT) genes in the fecal microbiome of Humboldt penguins (). The occurrence of natural anti-α-Gal antibodies (Abs) in sera and eggs of healthy Humboldt penguins was also assessed. A trial was then conducted to test whether oral administration of Nissle, expressing high α-Gal levels, modulates anti-α-Gal immunity in a colony of Humboldt penguins. Animals in the vaccination and placebo groups were evaluated before the trial and followed for one year for aspergillosis detection using a diagnostic panel including computed tomography scans, capillary zone electrophoresis, 3-hydroxybutyrate levels, and anti- Abs. Anti-α-Gal Abs were detected in sera (IgM and IgY) and eggs (IgY) of healthy penguins. Microbiota analysis and functional predictions revealed the presence of α1,3GT genes in the microbiota of Humboldt penguins and other penguin species. A strong decrease in anti-α-Gal IgM levels was observed in all animals in the placebo group three months after vaccination protocol. This decrease was not observed in Nissle-treated penguins. After the vaccination protocol, we found a positive correlation between anti- IgY and anti-α-Gal IgY in the Nissle group, suggesting a correlation between the presence of the bacteria and these Abs. During the study period, three penguins exhibited respiratory signs consistent with aspergillosis. Two were from the placebo group whose symptoms resolved with specific treatments, while a single vaccinated individual developed fatal respiratory aspergillosis eight months after the trial. We conclude that Nissle represents a safe potential probiotic with a protective effect against aspergillosis in Humboldt penguins that deserves to be further explored for therapeutic uses in these animals.
Palinauskas V, Mateos-Hernandez L, Wu-Chuang A, de la Fuente J, Aželytė J, et al.
Frontiers in immunology •
Natural antibodies (Abs), produced in response to bacterial gut microbiota, drive resistance to infection in vertebrates. In natural systems, gut microbiota diversity is expected to shape the spectrum of natural Abs and resistance to parasites. This hypothesis has not been empirically tested. In this 'Hypothesis and Theory' paper, we propose that enteric microbiota diversity shapes the immune response to the carbohydrate α-Gal and resistance to avian malaria. We further propose that anti-α-Gal Abs are transmitted from mother to eggs for early malaria protection in chicks. Microbiota modulation by anti-α-Gal Abs is also proposed as a mechanism favoring the early colonization of bacterial taxa with α1,3-galactosyltransferase (α1,3GT) activity in the bird gut. Our preliminary data shows that bacterial α1,3GT genes are widely distributed in the gut microbiome of wild and domestic birds. We also showed that experimental infection with the avian malaria parasite induces anti-α-Gal Abs in bird sera. The bird-malaria-microbiota system allows combining field studies with infection and transmission experiments in laboratory animals to test the association between microbiota composition, anti-α-Gal Abs, and malaria infection in natural populations of wild birds. Understanding how the gut microbiome influences resistance to malaria can bring insights on how these mechanisms influence the prevalence of malaria parasites in juvenile birds and shape the host population dynamics.