Anaplasmataceae in wild rodents and roe deer from Trento Province (northern Italy).
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Anaplasmataceae↗
Biomedical subjects
T Beninati
Publications and source records attributed to T Beninati.
Widespread distribution and high prevalence of an alpha-proteobacterial symbiont in the tick Ixodes ricinus.
The tick Ixodes ricinus is responsible for the transmission of a number of bacterial, protozoan and viral diseases to humans and animals in Europe and Northern Africa. Female I. ricinus from England, Switzerland and Italy have been found to harbour an intracellular alpha-proteobacterium, designated IricES1, within the cells of the ovary. IricES1 is the only prokaryote known to exist within the mitochondria of any animal or multicellular organism. To further examine the distribution, prevalence and mode of transmission of IricES1, we performed polymerase chain reaction screening of I. ricinus adults from 12 countries across its geographic distribution, including tick colonies that have been maintained in the laboratory for varying periods of time. IricES1 was detected in 100% of field-collected female ticks from all countries examined (n = 128), while 44% of males were found to be infected (n = 108). Those males that are infected appear to harbour fewer bacteria than females. Sequencing of fragments of the 16S rRNA and gyrB genes revealed very low nucleotide diversity among various populations of IricES1. Transmission of IricES1 from engorged adult females to eggs was found to be 100% (n = 31). In tick colonies that had been maintained in the laboratory for several years, a relatively low prevalence was found in females (32%; n = 25). To our knowledge, IricES1 is the most widespread and highly prevalent of any tick-associated symbiont.
Alphaproteobacteria↗
Phylogeny of Wolbachia pipientis based on gltA, groEL and ftsZ gene sequences: clustering of arthropod and nematode symbionts in the F supergroup, and evidence for further diversity in the Wolbachia tree.
Current phylogenies of the intracellular bacteria belonging to the genus Wolbachia identify six major clades (A-F), termed 'supergroups', but the branching order of these supergroups remains unresolved. Supergroups A, B and E include most of the wolbachiae found thus far in arthropods, while supergroups C and D include most of those found in filarial nematodes. Members of supergroup F have been found in arthropods (i.e. termites), and have previously been detected in the nematode Mansonella ozzardi, a causative agent of human filariasis. To resolve the phylogenetic positions of Wolbachia from Mansonella spp., and other novel strains from the flea Ctenocephalides felis and the filarial nematode Dipetalonema gracile, the authors generated new DNA sequences of the Wolbachia genes encoding citrate synthase (gltA), heat-shock protein 60 (groEL), and the cell division protein ftsZ. Phylogenetic analysis confirmed the designation of Wolbachia from Mansonella spp. as a member of the F supergroup. In addition, it was found that divergent lineages from Dip. gracile and Cte. felis lack any clear affiliation with known supergroups, indicating further genetic diversity within the Wolbachia genus. Finally, although the data generated did not permit clear resolution of the root of the global Wolbachia tree, the results suggest that the transfer of Wolbachia spp. from arthropods to nematodes (or vice versa) probably occurred more than once.
Animals↗
A symbiont of the tick Ixodes ricinus invades and consumes mitochondria in a mode similar to that of the parasitic bacterium Bdellovibrio bacteriovorus.
We have recently performed molecular characterisation of an intracellular alpha-proteobacterium, named IricES1, which resides in the ovarian tissue of female Ixodes ricinus ticks from Italy. A unique characteristic of this bacterium is its ability to invade the mitochondria of the cells in which it resides. Although some ultrastructural studies have been performed on close relatives of this bacterium from I. ricinus in England and Switzerland, a number of questions remain about its movement within ovarian tissues and mitochondria. We have performed the first detailed ultrastructural examination of IricES1 in engorged female adult I. ricinus. Among our findings was that the bacterium enters mitochondria in a similar way to that employed by the 'predatory' bacterium Bdellovibro bacteriovorus, that is, between the inner and outer membranes. It then appears to multiply, with the new 'colony' consuming the mitochondrial matrix. Despite having many of their mitochondria consumed, oocytes appear to develop normally, and the bacteria are likely to be vertically transferred to all eggs.
Animals↗
Lyme disease and babesiosis: preliminary findings on the transmission risk in highly frequented areas of the Monti Sibillini National Park (Central Italy).
The Monti Sibillini National Park is a recently borne protected area in the central Apennines that has become an important tourist destination. Mountain grasslands and woods have made it also a suitable habitat for sheep and bovine cattle, as well as for wild animals such as the wild bore and the roe deer. Therefore, a preliminary investigation was conducted to assess the risk of transmission of tick-borne zoonoses, such as Lyme disease and Babesiosis, by actively looking for both the arthropod vector and the causative agent. For two consecutive years, ambushing ticks were collected in four distinct geographical areas, comprehensive of many highly frequented tourist places. The tick fauna, tick habitats and the seasonal distribution of the different tick life stages collected with the method of "flagging and dragging" have been reported. Almost all the collected specimens belonged to the species Haemaphysalis punctata (Canestrini and Fanzago) (Acari: Ixodidae), which was found moderately infected with Babesia spp. Only a few Ixodes ricinus (Linnaeus) ticks, the most competent vector of Lyme disease, were found and on PCR examination all of them resulted negative as far as the infectious agent Borrelia burgdorferi sensu lato (Johnson) is concerned.
Animals↗
[Ixodes ricinus, transmitted diseases and reservoirs].
The tick Ixodes ricinus has been recorded in most Italian regions especially in thermo-mesophilous woods and shrubby habitats where the relative humidity allow the tick to complete its 3 year developmental cycle, as predicted for the European climatic ranges. This tick acts both as vector and reservoir for a series of wildlife zoonotic pathogens, especially the agents of Lyme diseases, Tick borne encephalitis and Human Granulocytic Ehrlichiosis, which are emerging in most of Europe. To assess the spatial distribution of these pathogens and the infection risk for humans and animals within the territory of the Province of Trento, we carried out a long term study using a combination of eco-epidemiological surveys and mathematical modelling. An extensive tick collection with a GIS based habitat suitability analysis allowed us to identify the areas where tick occurs at various density. To identify the areas with higher infection risk, we estimated the values of R0 for Borrelia burgdorferi s.l., TBE virus and Anaplasma phagocytophila under different ecological conditions. We assessed the infection prevalence in the vector and in the wildlife reservoir species that play a central role in the persistence of these infections, ie the small mammals A. flavicollis and C. glareolus. We also considered the double effect of roe deer (Capreolus capreolus) which act as reservoir for A. phagocytophila but is an incompetent host for B. burgdorferi and TBE virus, thus reducing the infection prevalence in ticks of these last two pathogens. Infection prevalence with B. burgdorferi and A. phagocytophila in the vector was assessed by PCR screening 1212 I. ricinus nymphs collected by dragging in six main study areas during 2002. The mean infection prevalence recorded was 1.32% for B. burgdorferi s.l. and 9.84% for A. phagocytophila. Infection prevalence in nymphs with TBE virus, as assessed in a previous study was 0.03%. Infection prevalence in rodents was assessed by screening (with ELISA and PCR) tissues and blood samples collected from 367 rodent individuals trapped extensively during 2002 within 6 main study areas. A. flavicollis (N=238) was found to be infected with all three pathogens investigated, with infection prevalence ranging from 3.3% for TBE virus to 11.7% for A. phagocytophila, and 16.6% with B. burgdorferi s.l. C. glareolus (N=108) showed an infection prevalence of 6.5% with A. phagocytophila and 12.7% with B. burgdorferi s.l., while no individuals were infected with TBE virus. We also screened 98 spleen samples collected from roe deer with PCR, resulting in a mean prevalence of infection with A. phagocytophila of 19.8%. Using a deterministic model we explored the condition for diseases persistence under different rodent and roe deer densities. R0 values resulted largely above 1 for B. burgdorferi s.l. in the vast majority of the areas classified as suitable for I. ricinus occurrence in Trentino, while the condition for TBE persistence appeared to be more restricted by a combination of climatic condition and host densities.
Anaplasma phagocytophilum↗
[Emerging rickettsioses].
Ticks are known to carry and transmit a number of microbial agents that cause diseases in humans and animals. Among these are members of the order Rickettsiales (alpha-proteobacteria), which include the genera Rickettsia and Ehrlichia. The most common and well-known Rickettsial human disease in Europe is Mediterranean Spotted Fever (MSF), caused by Rickettsia conorii. In recent years, a number of new Rickettsia species have been discovered in Europe, some of which have been shown to be pathogenic to humans. These discoveries have been facilitated by use of sequence-based molecular identification techniques. In Italy, it is generally believed that R. conorii is the only Rickettsia species present, and clinical tests for MSF rely on antigens raised against this bacterium. We are currently undertaking a molecular screening study of Rickettsiales-bacteria in ticks from various regions of Italy, to check for the potential presence of species from this order recently discovered in other parts of Europe. So far, we have identified a number of additional species in ticks collected from northern, central and southern regions. These include the known pathogens R. helvetica and R. slovaca as well as two species which may or may not be of medical relevance: R. monacensis and R. sp. IRS4. As a part of this survey, we have identified a novel alphaproteobacterium from the medically important tick Ixodes ricinus. This bacterium, tentatively named IricES1, has the unusual property of existing within the mitochondria, as well as the cytoplasm, of ovarian cells. To our knowledge, this is the only known example of a bacterium that is able to enter the mitochondria of animals. Our recently published electron microscopic data indicates that the bacterium enters mitochondria between the inner and outer membranes, and then proceeds to consume the inner mitochondrial matrix. We will present further data on this bacterium, including: 1) its phylogenetic position based on various molecular sequences, 2) its localization within the tick based on in situ hybridization; 3) its distribution among tick populations in Europe; 4) preliminary data on attempts at culturing this bacterium in a variety of cell types. Possible interactions between the bacterium and its host will be discussed. Ticks are known to carry and transmit a number of microbial agents that cause diseases in humans and animals. Among these are members of the order Rickettsiales (alpha-proteobacteria), which include the genera Rickettsia and Ehrlichia. The most common and well-known Rickettsial human disease in Europe is Mediterranean Spotted Fever (MSF), caused by Rickettsia conorii. In recent years, a number of new Rickettsia species have been discovered in Europe, some of which have been shown to be pathogenic to humans. These discoveries have been facilitated by use of sequence-based molecular identification techniques. In Italy, it is generally believed that R. conorii is the only Rickettsia species present, and clinical tests for MSF rely on antigens raised against this bacterium. We are currently undertaking a molecular screening study of Rickettsiales-bacteria in ticks from various regions of Italy, to check for the potential presence of species from this order recently discovered in other parts of Europe. So far, we have identified a number of additional species in ticks collected from northern, central and southern regions. These include the known pathogens R. helvetica and R. slovaca as well as two species which may or may not be of medical relevance: R. monacensis and R. sp. IRS4. As a part of this survey, we have identified a novel alphaproteobacterium from the medically important tick Ixodes ricinus. This bacterium, tentatively named IricES1, has the unusual property of existing within the mitochondria, as well as the cytoplasm, of ovarian cells. To our knowledge, this is the only known example of a bacterium that is able to enter the mitochondria of animals. Our recently published electron microscopic data indicates that the bacterium enters mitochondria between the inner and outer membranes, and then proceeds to consume the inner mitochondrial matrix. We will present further data on this bacterium, including: 1) its phylogenetic position based on various molecular sequences, 2) its localization within the tick based on in situ hybridization; 3) its distribution among tick populations in Europe; 4) preliminary data on attempts at culturing this bacterium in a variety of cell types. Possible interactions between the bacterium and its host will be discussed.
Animals↗