A. phagocytophilum, une bactérie transmise par les tiques, est responsable de l’anaplasmose granulocytaire, une maladie émergente qui infecte une large gamme de mammifères dont l’homme. Actuellement, la description des cycles épidémiologiques de cette bactérie est incomplète. L’objectif de cette thèse est de caractériser la diversité génétique d’A. phagocytophilum chez différentes espèces d’hôtes, afin de déterminer quelles espèces participent au même cycle épidémiologique. D’abord, nous avons caractérisé la diversité génétique d’A. phagocytophilum chez les animaux domestiques malades à l’aide d’une MLSA. Nous avons identifié trois groupes de génotypes infectant les bovins, dont un groupe est partagé avec les chevaux et les chiens, et un avec les chevreuils. Ensuite, nous avons recherché quelles espèces de tiques pouvaient transmettre la bactérie, et quels pouvaient être les réservoirs parmi les mammifères sauvages. En Camargue, un génotype au fort potentiel zoonotique a été identifié chez cinq espèces de tiques du genre Rhipicephalus, Dermacentor et Hyalomma. La prévalence chez des rongeurs suggère qu’ils peuvent être réservoirs, mais la présence de génotypes infectant les bovins chez les mulots est à vérifier. Enfin, la comparaison des génotypes obtenus chez les tiques et les chevreuils par séquençage 454, a montré que la contribution des chevreuils à l’infection des tiques était faible sur le site des Vallons de Gascogne. L’absence de rongeurs infectés sur ce site suggère que d’autres mammifères réservoirs sont présents. Cette étude montre la complexité des cycles d’A. phagocytophilum et l’intérêt des outils moléculaires. / A. phagocytophilum, a tick-borne bacterium, is responsible of the granulocytic anaplasmosis, an emerging disease that infects a large range of mammals including humans. Currently, the description of the epidemiological cycles of this bacterium is incomplete. The objective of this thesis was to characterize the genetic diversity of A. phagocytophilum in different host species to determine those involved in the same epidemiological cycle. First, we characterized the genetic diversity of A. phagocytophilum in sick domestic animals with a MLSA. We identified three groups of genotypes infecting cattle, including one group shared with horses and dogs, and another shared with roe deer. Then, we investigated what species of ticks can transmit the bacteria, and what wild mammals could be reservoirs. In Camargue, a genotype with high zoonotic potential was identified in five species of ticks of the genus Rhipicephalus, Dermacentor and Hyalomma. The prevalence in French rodents suggests that they may be reservoir hosts, but the presence of genotypes infecting cattle in rodents must be checked. Finally, comparing the bacterial genotypes in ticks and roe deer by 454 sequencing, showed that the contribution of the roe deer to tick infection was low in the site of “Vallons de Gascogne”. The absence of infected rodents in this location suggests that other reservoir mammals are present. This study demonstrates the complexity of the A. phagocytophilum cycle and the contribution of molecular tools.

Obligate intracellular pathogens must acquire host cell-derived nutrients to facilitate their survival. One such bacterial pathogen, Anaplasma phagocytophilum, replicates within neutrophils and non-phagocytic cells in a bacterial-modified, host cell-derived vacuole. The bacterium exploits host cell vesicular trafficking pathways to route nutrients to its vacuole and utilizes Rab GTPases, guanine nucleotide-dependent, vesicular trafficking regulators, to do so. We previously discovered that the A. phagocytophilum vacuolar membrane is decorated with a specific subset of Rab GTPases - Rab1, Rab4A, Rab10, Rab11, Rab14, Rab22A and Rab35. Rab1 is exclusively found on the endoplasmic reticulum (ER) and thus its localization suggests that the bacterium intercepts the ER. Rab10, which is found on the ER, trans-Golgi and recycling endosomes, localizes to the vacuolar membrane in a guanine nucleotide-independent and bacterial protein synthesis-dependent manner. This suggests that a bacterial-encoded protein is binding to and recruiting Rab10. In this study, we determined that A. phagocytophilum hijacks two very nutrient-rich sources in the secretory pathway - trans-Golgi- and endoplasmic reticulum-derived vesicles. A. phagocytophilum localizes perinuclearly adjacent to the Golgi apparatus during infection. A. phagocytophilum and Anaplasma marginale, an intravacuolar bovine pathogen, also localize near the smooth ER and rough ER in both mammalian and tick host cells. These results are supported by transmission electron microscopy analyses of infected cells. Membrane markers for the rough ER label the peripheries of A. marginale and A. phagocytophilum organisms in both mammalian and tick host cells, which suggests that they are translocated into the pathogen vacuole. Furthermore, membrane markers for trans-Golgi-derived vesicles, including endogenous Rab10, label the periphery of intravacuolar A. phagocytophilum organisms. Markers for the trans-Golgi and the ER co-fractionate with A. phagocytophilum in density gradient centrifugation studies. siRNA knockdown of Rab10 pronouncedly reduces delivery of trans-Golgi markers into the pathogen-occupied vacuole, significantly reduces infection, and impedes bacterial conversion to the bacterium’s dense-cored form. These results suggest that trans-Golgi recruitment is Rab10 dependent and is critical for bacterial development. We identified an outer membrane A. phagocytophilum moonlighting protein, uridine monophosphate kinase that specifically binds GST-Rab10 in affinity chromatography assays and interacts with Rab10 in vivo. We hypothesize that this surface protein is mediating the interaction of the bacteria with intravacuolar trans-Golgi derived vesicles. This interaction could be critical for the delivery of essential nutrients. Taken together, these data suggest that nutritional virulence mechanisms of A. phagocytophilum and A. marginale target the host secretory pathway. Additionally, they suggest a novel mechanism whereby pathogens translocate nutrient rich vesicles into the pathogen vacuole, thus delivering essential nutrients right to their front door.

Anaplasma phagocytophilum and A. marginale are the etiologic agents of human granulocytic anaplasmosis and bovine anaplasmosis, respectively. Both diseases can be severe, even fatal, and protective vaccines for each are lacking. We recently identified A. phagocytophilum outer membrane protein A (ApOmpA) as being critical for cellular invasion and is expressed during infection of mammalian but not tick cells. Disrupting ApOmpA-host cell interactions significantly inhibits A. phagocytophilum entry into host cells. ApOmpA and its A. marginale ortholog, AM854 (A. marginale OmpA; AmOmpA) exhibit 44% amino acid identity. The ApOmpA invasin domain is highly conserved between both proteins. In this study, we investigated the differential expression of AmOmpA in mammalian versus tick cell lines; the serological cross-reactivity between AmOmpA and ApOmpA; the potential role of AmOmpA in mediating interactions with mammalian host cells; and if inhibiting the AmOmpA-host cell interaction impairs A. marginale cellular invasion. AmOmpA is expressed throughout infection of mammalian, but not tick cells. Sera from A. marginale infected cows recognized both AmOmpA and ApOmpA. Sera from cows immunized with an A. marginale OM complex that conferred protection also recognized both proteins. Thus, ApOmpA and AmOmpA share cross-reactive B-cell epitopes. To determine if AmOmpA plays a role in promoting A. marginale infection, we assessed the abilities of recombinant AmOmpA to competitively inhibit infection of mammalian host cells. To examine the cross-reactive properties of OmpA, we showed that preincubation of host cells with GST-ApOmpA and pretreatment of A. marginale with anti-GST-ApOmpA significantly inhibit A. marginale infection of host cells; and that pretreatment of A. phagocytophilum with serum from cows immunized with an A. marginale OM complex reduces its infection of host cells. These studies advance understanding of conservation of OmpA-mediated cellular invasion between Anaplasma species and highlight the potential of OmpA as a vaccinogen that could offer protection against human and veterinary anaplasmoses.

Obligate intracellular pathogens must invade host cells to survive and pose a global health risk. As such, internalization is a critical life stage and represents an excellent therapeutic target. Oxidoreductase exploitation is a thematic invasion strategy among obligate intracellular pathogens. Delineating the mechanisms and proteins mediating this exploitation could identify novel therapeutic targets for many important pathogens. Anaplasma phagocytophilum infects neutrophils by an incompletely defined mechanism, resulting in the emerging potentially fatal disease, human granulocytic anaplasmosis. The bacterial adhesin, Asp14, contributes to invasion by virtue of its C-terminus engaging an unknown receptor. Yeast two-hybrid analysis identified protein disulfide isomerase (PDI) as a putative Asp14 binding partner. Co-immunoprecipitation confirmed this interaction and identified the Asp14 C-terminus as critical to it. PDI reductase activity inhibition impaired bacterial infection of, but not binding to, host cells. A. phagocytophilum failed to productively infect myeloid-specific PDI conditional knock-out mice. This is the first demonstration of microbial PDI exploitation in vivo. Infection of PDI inhibited cells was rescued when bacterial, but not host surfaces were reduced with the reducing agent tris(2-carboxyethyl)phosphine (TCEP). Furthermore, TCEP restored bacterial infectivity after Asp14 inhibition using an antibody that reduces infection. Mutational analyses identified Asp14 residues critical for binding PDI. These data demonstrate that Asp14 binds and brings PDI to disulfide bonds within A. phagocytophilum surface protein(s) that it reduces, enabling infection. Targeting the Asp14 C-terminus could benefit approaches to prevent/treat granulocytic anaplasmosis. A similar approach would identify proteins from other obligate intracellular pathogens that could prove to be protective targets.

Submitted by Reginaldo Soares de Freitas (reginaldo.freitas@ufv.br) on 2018-06-28T17:20:50Z No. of bitstreams: 1 texto completo.pdf: 1170314 bytes, checksum: aef38342ffa69b1c377766d841c96e8c (MD5) / Made available in DSpace on 2018-06-28T17:20:50Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1170314 bytes, checksum: aef38342ffa69b1c377766d841c96e8c (MD5) Previous issue date: 2018-02-23 / Neste estudo foram analisadas 100 amostras de sangue de cães, com trombocitopenia marcada (plaquetas < 100.000/μL) ou com visualização direta de hemoparasitas (ou inclusões compatíveis) no esfregaço sanguíneo, obtidas da rotina do laboratório de análises clínicas do DVT (Departamento de Veterinária), do Hospital Veterinário da Universidade Federal de Viçosa (UFV). As amostras foram submetidas à extração de DNA e posteriormente à reação em cadeia da polimerase de tipo nested (nPCR), para o diagnóstico molecular de A. phagocytophilum e outros hemoparasitas. Do total das amostras, 60 foram positivas para no mínimo um hemoparasita. Foi possível detectar a presença de quatro gêneros de hemoparasitas nas amostras de sangue avaliadas: Ehrlichia, Anaplasma, Babesia e Hepatozoon. Foram amplificadas um total de 26 produtos do primer Ehrlichia spp monocítica, 23 de Ehrlichia spp granulocítica 26 com BAB-rum e 10 utilizando o hsp70. Logo ao analisar os resultados, de um total de 86 amostras foi possível identificar os seguintes hemoparasitas: 23 E. canis (identidade 94%-100%), 7 A. platys (identidade 97%-100%), 11 B. vogeli (identidade 86%-99%) e 15 H. canis (identidade 94%-99%). Nenhuma amostra foi positiva utilizando o primer msp4, específico de A. phagocytophilum, porém, o sequenciamento de uma das amostras amplificadas teve uma identidade de 99% com um fragmento da sequência parcial do gene 16S rRNA de A. phagocytophilum depositada no GenBank. A não amplificação de produtos com um primer específico para A. phagocytophilum pode ser atribuída a diversas hipóteses, mas isto não exclui a possibilidade que a bactéria esteja presente no município de Viçosa ou da microrregião. / In this study were analyzed blood samples from 100 dogs, with marked thrombocytopenia (platelets/μL < 100,000) or with direct visualization of hemoparasites (or compatible inclusions) in the blood smear, obtained from the routine of the clinical analysis laboratory, of the DVT (Veterinary Department), from the Veterinary Hospital da Universidade Federal de Viçosa (UFV). The samples were submitted for DNA extraction and subsequently to polymerase chain reaction of nested type (nPCR), for the molecular diagnosis of A. phagocytophilum and other hemoparasites. From all the samples, 60 were positive for at least one hemoparasite. It was possible to detect the presence of four genera of hemoparasites in the blood samples assessed: Ehrlichia, Anaplasma, Babesia and Hepatozoon. Were amplified a total of 26 products from the monocytic ehrlichia spp primer, 23 from the granulocytic ehrlichia spp primer, 26 with BAB-rum primer and 10 using the hsp70 primer. After analyzing the results, from a total of 85 it was possible to identify the following hemoparasites: 23 E. canis (identity 94%- 100%), 7 A. platys (identity 97%-100%), 11 B. vogeli (identity 86%-99%) and 15 H. canis (94% -99% identity). No samples were positive using the msp4 primer, specific for A. phagocytophilum, however, the sequence of one of the amplified samples had a 99% identity with a partial sequence of the 16S rRNA gene of A. phagocytophilum deposited on GenBank. The non- amplification of products with a specific primer for A. phagocytophilum can be attributed to several hypotheses, but this does not exclude the possibility that the bacterium is present in the municipality of Viçosa or in the microregion.

Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum are causative agents of Lyme disease and human granulocytic anaplasmosis. Their common vector in Europe are the ticks from the genus Ixodes. In our work, we focused on interaction of innate immune cells with the causative agent of Lyme diseases, that are insubstitutable in their function in the early phase of the disease. Anaplasma phagocytophilum is hard to cultivate, the only possibility is to cultivate it in cell cultures. Successful cultivation of Anaplasma phagocytophilum acquired from patients in our geographic area is crucial for following experiments and for diagnostics too. In our experiments, we used validated cell cultures of HL-60 cells, canine monocytes DH82 and murine monocytes P388D1. During our studies of interaction of the causative agent of Lyme diseases with cells, we used two strains of different species Borrelia. Borrelia garinii M192 and Borrelia burgdorferi sensu stricto B31. These strains vary in virulence. The strain M192 is virulent, but the strain B31 lost its virulence by passages. We specialised in study of morphological changes using light microscopy (observation of dyed and fixed preparates and observation in dark field), eventually by transmision electron microscopy. During our experiments, we concluded that HL-60...

Globally, vector borne diseases cause more than a million deaths each year and more than a billion infections in humans. Ticks are of big medicinal importance since they can transmit pathogens that can cause serious infections. Some recently discovered pathogens that can cause infections in humans are Anaplasma phagocytophilum (A. phagocytophilum) that can cause human granulocytic anaplasmosis (HGA) and Candidatus Neoehrlichia mikurensis (N. mikurensis) that can cause Neoehrlichiosis. It is still widely unknown how prevalent these pathogens are, if ticks can be infected with both of these pathogens and if these pathogens can be transovarially transmitted from adult female to egg and larvae. This study aims to screen for these pathogens in collected ticks from southern Sweden and to detect eventual co-infections and transovarial transmission. A real-time qPCR assay targeting the 16S rRNA gene of N. mikurensis and other Anaplasmataceae was applied on 1356 Ixodes ricinus (I. ricinus) ticks collected from 5 sites in southern Sweden. Positive samples were subjected to Sanger sequencing. A. phagocytophilum occurred in 4.64 % of the ticks, N. mikurensis occurred in 1.33 % of the ticks and also Rickettsia was found to occur in 6.27 % of the ticks. No co-infection was detected. Some samples of tick larvae showed positive results after qPCR, indicating transovarial transmission, but none of the sequences were readable.

Ixodes genties erkės yra krauju mintantys nariuotakojai, visų – stuburinių gyvūnų, taip pat žmogaus parazitai. Ixodes ricinus erkės perneša daugybę ligų sukėlėjų, tokių kaip: erkinio encefalito (erkinio encefalito virusas), Laimo ligos (Borrelia burgdorferi sensu lato bakterijos), bebeziozės sukėlėjus (Babesia microti ir Babesia divergens). Taip pat platina ir Anaplasma phagocytophilum bakterijas. Šiuo metu erkių platinamos ligos yra dažniausios vektorių sukeliamos infekcijos Europoje. Pastaraisiais metais išpopuliarėjo molekulinės biologijos metodai, paremti patogenų nukleino rūgščių polimerazės grandinine reakcija ir RLB hibridizacija. Šie metodai laikomi tinkamiausiais, jautriausiais ir specifiškiausiais erkių platinamų ligų sukėlėjų diagnostikai. Šiame darbe naudoti molekuliniai metodai erkių platinamų ligų sukėlėjų: erkinio encefalito viruso, Anaplasma phagocytophilum, Borrelia burgdorferi sensu lato ir Babesia spp., nustatymui iš 2200 erkių, surinktų keturiuose Lietuvos rajonuose. Tyrimų metu nustatyti šeši erkinio encefalito viruso infekcijų atvejai, iš kurių penki teigiami mėginiai nustatyti Radviliškio raj. surinktose erkėse ir vienas – Utenos raj. Anaplasma phagocytophilum bakterijų infekcijos yra dažniausiai pasitaikančios infekcijos Lietuvos erkėse. Tyrimų metu nustatyti 37 (3 %) teigiami Anaplasma phagocytophilum mėginiai, iš kurių 17 (46 %) nustatyti Kėdainių raj. surinktose erkėse, 15 (32 %) – Klaipėdos, 5 (14 %) – Radviliškio ir 3 (8 %) – Utenos raj. Tarp šių... [toliau žr. visą tekstą] / Ticks of genus Ixodes that infect livestock, deer, dogs, and a wide variety of other species including humans. Ixodes ricinus can also transmit numerous diseases including tick-borne encephalitis, Lyme diseases (Borrelia burgdorferi sensu lato infections), babesiosis (Babesia microti and Babesia divergens infections). It can also spread Anaplasma phagocytophilum bacteria. Now tick-borne infections are the most frequent human vector-borne infections in Europe, the incidence of these infections has been on rise, and new infections have emerged. In recent years, molecular detection methods based on PCR amplification of the nucleic acids of pathogens and Reverse Line blot hybridization have been showed to be effective, sensitive and specific methods for diagnosis of tick-borne diseases. In this work were used molecular detection methods for tick-borne pathogens: tick-borne encephalitis virus (TBEV), Anaplasma phagocytophilum, Borrelia burgdorferi sensu lato, and Babesia spp., diagnostics in 2200 ticks collected in four Lithuanian regions forests. During investigation were identified six cases of TBEV, which five positive samples were from ticks collected in Radviliškis region and one from Utenos region forest. Anaplasma phagocytophilum bacteria infections were most frequent in Lithuanian ticks, during researches were identified 37 (3 %) cases (17 (46 %) in Kėdainių region, 15 (32 %) – Klaipėdos, 5 (14 %) – Radviliškio, and 3 (8 %) – Utenos region). In these 81 % were in adult... [to full text]

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The present thesis examines questions related to the temporal origin of the Flavivirus genus and the ecology of tick-borne pathogens. In the first study, we date the origin and divergence time of the Flavivirus genus. It has been argued that the first flaviviruses originated after the last glacial maximum. This has been contradicted by recent analyses estimating that the tick-borne flaviviruses emerged at least before 16,000 years ago. It has also been argued that the Powassan virus was introduced into North America at the time between the opening and splitting of the Beringian land bridge. Supported by tip date and biogeographical calibration, our results suggest that this genus originated circa 120,000 (156,100–322,700) years ago if the Tamana bat virus is included in the genus, or circa 85,000 (63,700–109,600) years ago excluding the Tamana bat virus. In the second study we estimate the prevalence of tick-borne encephalitis virus (TBEV) in host-seeking Ixodes ricinus from 29 localities in Sweden and compare our data with those of neighbouring countries. Nymphs and adult ticks were screened for TBEV using a real-time PCR assay. The mean TBEV prevalence for all tick stages combined was 0.26% for Sweden and 0.28% for all Scandinavian countries, excluding Iceland. The low prevalence of TBEV in nature may partly be explained by the fact that TBEV occurs in spatially small foci and that the inclusion of ticks from non-infected foci will reduce the prevalence estimate. In the third and fourth study, we conducted the first large-scale investigations to estimate the prevalence and geographical distribution of Anaplasma spp. and Rickettsia spp. in host-seeking larvae, nymphs and adults of I. ricinus ticks in Sweden. Ticks were collected from several localities in central and southern Sweden and were subsequently screened for the presence of Anaplasma spp. and Rickettsia spp. using a real-time PCR assay. For all active tick stages combined, the mean prevalence of Anaplasma spp. and Rickettsia spp. in I. ricinus in Sweden was estimated to 1.1% and 4.8%, respectively. It was also shown that A. phagocytophilum and R. helvetica are the main Anaplasma and Rickettsia species occurring in Sweden.