Toxoplasma Gondii infections in stranded marine mammals in France and Romania

Marine mammals are major sentinel species for the research concerning contamination of marine environment by terrestrial pathogens and are early warnings for the emergence or resurgence of infectious diseases. Protozoal parasites such as Toxoplasma Gondii and Sarcocystis spp. and the helminth parasites Trichinella spp. can infect many species of marine mammals worldwide. T. Gondii and Trichinella spp. zoonotic infections are a matter of concern for human health, because consumption of marine mammal meat is frequent in some regions of the world. Extensive seroprevalence investigations have been made in some parts of the world, showing a high presence of T. Gondii infections in marine animals, yet little is known about it in France and Romania. This study indicates the exposure of cetaceans and pinnipeds from France and Romania to T. Gondii and should be pursued by large-scale studies. This is the first report on the detection of T. Gondii antibodies in cetaceans and seals in France and Romania and the first identification of T. Gondii in a sperm whale.Les mammifères marins sont des sentinelles de premier choix pour l’étude de la contamination du milieu marin par des pathogènes terrestres et permettent d’attirer l’attention en cas d’apparition ou de recrudescence de maladies infectieuses. Les protozoaires Toxoplasma Gondii et Sarcocystis spp., le nématode Trichinella nativa sont retrouvés fréquemment chez de nombreuses espèces de mammifères marins à travers le monde. Le parasitisme de ces animaux par des agents zoonotiques (Toxoplasma Gondii et Trichinella nativa) a un impact en santé publique, puisque leur viande est susceptible d’être consommée dans de nombreux pays. De nombreuses enquêtes de séroprévalence ont détecté la présence fréquente d’infections par T. Gondii chez les mammifères marins. Première étude du genre en France et en Roumanie, elle met en évidence la présence du parasite T. Gondii chez les cétacés et les pinnipèdes des eaux françaises et roumaines et pour la première fois chez un cachalot

Exploring the Susceptibility of C3H Mice to Tick-Borne Encephalitis Virus Infection: Implications for Co-Infection Models and Understanding of the Disease

Ticks and tick-borne diseases (TBDs) are increasingly recognized as a critical One Health concern. Tick-borne encephalitis (TBE), a severe neuro infection caused by the tick-borne encephalitis virus (TBEV), has emerged as a significant global public health threat. Laboratory animals, particularly mice, have played a pivotal role in advancing our understanding of TBD pathogenesis. Notably, BALB/c mice have been employed as models due to their heightened susceptibility to TBEV. However, the use of C3H mice, valued for other tick-borne pathogens, has remained unexplored for TBEV until now. This study aimed to assess the susceptibility of C3H mice to TBEV infection, laying the groundwork for future co-infection models involving TBEV and Borrelia. Experiments revealed that C3H mice are susceptible to TBEV infection through subcutaneous inoculation. While 102 PFU/mouse appeared necessary for full infection, 103 PFU/mouse induced consistent symptoms. However, subsequent assessment of ticks’ acquisition of TBEV from infected mice met with limited success, raising questions about optimal infectious doses for natural infection. These findings suggest the potential of C3H mice for studying TBEV and co-infections with other pathogens, particularly Borrelia. Further exploration of the interplay between these pathogens, their transmission dynamics, and disease severity could enhance prevention and control strategies

Comparative genomics of first available bovine Anaplasma phagocytophilum genome obtained with targeted sequence capture.

Background: [br/] Anaplasma phagocytophilum is a zoonotic and obligate intracellular bacterium transmitted by ticks. In domestic ruminants, it is the causative agent of tick-borne fever, which causes significant economic losses in Europe. As A. phagocytophilum is difficult to isolate and cultivate, only nine genome sequences have been published to date, none of which originate from a bovine strain. Our goals were to; 1/ develop a sequencing methodology which efficiently circumvents the difficulties associated with A. phagocytophilum isolation and culture; 2/ describe the first genome of a bovine strain; and 3/ compare it with available genomes, in order to both explore key genomic features at the species level, and to identify candidate genes that could be specific to bovine strains.[br/] [br/] Results:[br/] DNA was extracted from a bovine blood sample infected by A. phagocytophilum. Following a whole genome capture approach, A. phagocytophilum DNA was enriched 197-fold in the sample and then sequenced using Illumina technology. In total, 58.9% of obtained reads corresponded to the A. phagocytophilum genome, covering 85.3% of the HZ genome. Then by performing comparisons with nine previously-sequenced A. phagocytophilum genomes, we determined the core genome of these ten strains. Following analysis, 1281 coding DNA sequences, including 1001 complete sequences, were detected in the A. phagocytophilum bovine genome, of which four appeared to be unique to the bovine isolate. These four coding DNA sequences coded for "hypothetical proteins of unknown function” and require further analysis. We also identified nine proteins common to both European domestic ruminants tested.[br/] [br/] Conclusion:[br/] Using a whole genome capture approach, we have sequenced the first A. phagocytophilum genome isolated from a cow. To the best of our knowledge, this is the first time that this method has been used to selectively enrich pathogenic bacterial DNA from samples also containing host DNA. The four proteins unique to the A. phagocytophilum bovine genome could be involved in host tropism, therefore their functions need to be explored

Selection of aptamers against Anaplasma phagocytophilum, a tick-borne and zoonotic bacterium

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Multiple-locus variable-number tandem repeat analysis potentially reveals the existence of two groups of Anaplasma phagocytophilum circulating in cattle in France with different wild reservoirs

Abstract Background Anaplasma phagocytophilum is the causative agent of tick-borne fever, a disease with high economic impact for domestic ruminants in Europe. Epidemiological cycles of this species are complex, and involve different ecotypes circulating in various host species. To date, these epidemiological cycles are poorly understood, especially in Europe, as European reservoir hosts (i.e. vertebrate hosts enabling long-term maintenance of the bacterium in the ecosystem), of the bacterium have not yet been clearly identified. In this study, our objective was to explore the presence, the prevalence, and the genetic diversity of A. phagocytophilum in wild animals, in order to better understand their implications as reservoir hosts of this pathogen. Methods The spleens of 101 wild animals were collected from central France and tested for the presence of A. phagocytophilum DNA by msp2 qPCR. Positive samples were then typed by multi-locus variable-number tandem repeat (VNTR) analysis (MLVA), and compared to 179 previously typed A. phagocytophilum samples. Results Anaplasma phagocytophilum DNA was detected in 82/101 (81.2%) animals including 48/49 red deer (98%), 20/21 roe deer (95.2%), 13/29 wild boars (44.8%), and 1/1 red fox. MLVA enabled the discrimination of two A. phagocytophilum groups: group A contained the majority of A. phagocytophilum from red deer and two thirds of those from cattle, while group B included a human strain and variants from diverse animal species, i.e. sheep, dogs, a horse, the majority of variants from roe deer, and the remaining variants from cattle and red deer. Conclusions Our results suggest that red deer and roe deer are promising A. phagocytophilum reservoir host candidates. Moreover, we also showed that A. phagocytophilum potentially circulates in at least two epidemiological cycles in French cattle. The first cycle may involve red deer as reservoir hosts and cattle as accidental hosts for Group A strains, whereas the second cycle could involve roe deer as reservoir hosts and at least domestic ruminants, dogs, horses, and humans as accidental hosts for Group B strains

Aptamers, an innovative tool to study Anaplasma phagocytophilum

International audienc

Sélection et développement d’aptamères dirigés contre A. phagocytophilum

International audienc

Aptamer selection against cell extracts containing the zoonotic obligate intracellular bacterium, Anaplasma phagocytophilum

International audienceAbstract A. phagocytophilum is a zoonotic and tick-borne bacterium, threatening human and animal health. Many questions persist concerning the variability of strains and the mechanisms governing the interactions with its different hosts. These gaps can be explained by the difficulty to cultivate and study A. phagocytophilum because of its strict intracellular location and the lack of specific tools, in particular monoclonal antibodies, currently unavailable. The objective of our study was to develop DNA aptamers against A. phagocytophilum, or molecules expressed during the infection, as new study and/or capture tools. Selecting aptamers was a major challenge due to the strict intracellular location of the bacterium. To meet this challenge, we set up a customized selection protocol against an enriched suspension of A. phagocytophilum NY18 strain, cultivated in HL-60 cells. The implementation of SELEX allowed the selection of three aptamers, characterized by a high affinity for HL-60 cells infected with A. phagocytophilum NY18 strain. Interestingly, the targets of these three aptamers are most likely proteins expressed at different times of infection. The selected aptamers could contribute to increase our understanding of the interactions between A. phagocytophilum and its hosts, as well as permit the development of new diagnostic, therapeutic or drug delivery appliances

New perspectives for the detection of Anaplasma phagocytophilum infection using aptamers

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