Vector Competence of the Tick Ixodes ricinus for Transmission of Bartonella birtlesii

Bartonella spp. are facultative intracellular vector-borne bacteria associated with several emerging diseases in humans and animals all over the world. The potential for involvement of ticks in transmission of Bartonella spp. has been heartily debated for many years. However, most of the data supporting bartonellae transmission by ticks come from molecular and serological epidemiological surveys in humans and animals providing only indirect evidences without a direct proof of tick vector competence for transmission of bartonellae. We used a murine model to assess the vector competence of Ixodes ricinus for Bartonella birtlesii. Larval and nymphal I. ricinus were fed on a B. birtlesii-infected mouse. The nymphs successfully transmitted B. birtlesii to naïve mice as bacteria were recovered from both the mouse blood and liver at seven and 16 days after tick bites. The female adults successfully emitted the bacteria into uninfected blood after three or more days of tick attachment, when fed via membrane feeding system. Histochemical staining showed the presence of bacteria in salivary glands and muscle tissues of partially engorged adult ticks, which had molted from the infected nymphs. These results confirm the vector competence of I. ricinus for B. birtlesii and represent the first in vivo demonstration of a Bartonella sp. transmission by ticks. Consequently, bartonelloses should be now included in the differential diagnosis for patients exposed to tick bites

Rac1 Dynamics in the Human Opportunistic Fungal Pathogen Candida albicans

The small Rho G-protein Rac1 is highly conserved from fungi to humans, with approximately 65% overall sequence identity in Candida albicans. As observed with human Rac1, we show that C. albicans Rac1 can accumulate in the nucleus, and fluorescence recovery after photobleaching (FRAP) together with fluorescence loss in photobleaching (FLIP) studies indicate that this Rho G-protein undergoes nucleo-cytoplasmic shuttling. Analyses of different chimeras revealed that nuclear accumulation of C. albicans Rac1 requires the NLS-motifs at its carboxyl-terminus, which are blocked by prenylation of the adjacent cysteine residue. Furthermore, we show that C. albicans Rac1 dynamics, both at the plasma membrane and in the nucleus, are dependent on its activation state and in particular that the inactive form accumulates faster in the nucleus. Heterologous expression of human Rac1 in C. albicans also results in nuclear accumulation, yet accumulation is more rapid than that of C. albicans Rac1. Taken together our results indicate that Rac1 nuclear accumulation is an inherent property of this G-protein and suggest that the requirements for its nucleo-cytoplasmic shuttling are conserved from fungi to humans

Broad and narrow personality traits as markers of one-time and repeated suicide attempts: A population-based study

<p>Abstract</p> <p>Background</p> <p>Studying personality traits with the potential to differentiate between individuals engaging in suicide attempts of different degrees of severity could help us to understand the processes underlying the link of personality and nonfatal suicidal behaviours and to identify at-risk groups. One approach may be to examine whether narrow, i.e., lower-order personality traits may be more useful than their underlying, broad personality trait dimensions.</p> <p>Methods</p> <p>We investigated qualitative and quantitative differences in broad and narrow personality traits between one-time and repeated suicide attempters in a longitudinal, population-based sample of young French Canadian adults using two multivariate regression models.</p> <p>Results</p> <p>One broad (Compulsivity: OR = 2.0; 95% CI 1.2–3.5) and one narrow personality trait (anxiousness: OR = 1.1; 95% CI 1.01–1.1) differentiated between individuals with histories of repeated and one-time suicide attempts. Affective instability [(OR = 1.1; 95% CI 1.04–1.1)] and anxiousness [(OR = .92; 95% CI .88–.95)], on the other hand, differentiated between nonattempters and one-time suicide attempters.</p> <p>Conclusion</p> <p>Emotional and cognitive dysregulation and associated behavioural manifestations may be associated with suicide attempts of different severity. While findings associated with narrow traits may be easier to interpret and link to existing sociobiological theories, larger effect sizes associated with broad traits such as Compulsivity may be better suited to objectives with a more clinical focus.</p

Création d'un "acarium" pour l'élevage et l'infection des tiques Ixodes ricinus sur le site d'Alfort

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Prevalence of five pathogenic agents in questing Ixodes ricinus ticks from Western France

International audienceIn Europe, Ixodes ricinus ticks are vectors of many emerging pathogens, including Borrelia burgdorferi sensu lato (sl), Anaplasma phagocytophilum, spotted fever group Rickettsia sp., Babesia sp., and very likely Bartonella sp. In this study, we looked for the presence of DNA of these microorganisms in 572 ticks from two forests in the west of France. DNA extraction and polymerase chain reaction (PCR) amplification were performed on individual nymphal, male, and female I. ricinus ticks. Amplification from 1 tick among the 572 samples (0.2%) resulted in PCR products with Bartonella-specific primers. Sequence analysis of the amplified fragment did not lead to species identification. Two ticks (0.3%) carried A. phagocytophilum–specific DNA. Eight ticks (1.4%) were positive with spotted fever group Rickettsia–specific primers, and all PCR fragments were related to Rickettsia helvetica. Thirty-five ticks (6.1%) were positive with B. burgdorferi sl–specific primers; the sequences were all related to Borrelia garinii or Borrelia afzelii, except one that was related to Borrelia carolinensis, a newly described species never reported in Europe so far. Thirty-five ticks (6.1%) carried Babesia sp. DNA. Female adults were more infected by B. burgdorferi sl than male adults. The prevalence of B. burgdorferi sl and Babesia sp. was significantly different between the two forests, with a higher prevalence of B. burgdorferi sl in ticks from the forest of Princé and a higher prevalence of Babesia sp. in ticks from the forest of Gâvre. To our knowledge, this is the first study that has detected all five pathogens in questing I. ricinus in the west of France and the first report of B. carolinensis DNA in ticks in Europe

Impact of feeding system and infection status of the blood meal on Ixodes ricinus feeding

International audienceArtificial membrane feeding systems are effective tools for both tick rearing and studying tick-borne pathogen transmission. In order to compare the effects of the type of feeding system on tick engorgement, Ixodes ricinus ticks were either fed on an artificial membrane feeding system or on live mice. Sheep and chicken blood were used with the membrane system to assess the effects of blood origin on tick engorgement. To investigate the effects of blood meal infection on tick engorgement, ticks were either fed with Bartonella-infected or uninfected blood, both via membrane feeding and on mice. The proportion of engorged ticks, the duration of tick feeding, and the weight of engorged ticks were assessed. Feeding on the artificial system led to a longer duration of tick feeding and a lower proportion of engorged ticks than when fed on mice, however, the weight of engorged ticks was unaffected. The proportion and weight of engorged ticks, as well as the duration of feeding were not affected by blood origin. Feeding on an infected blood meal or on infected mice decreased the proportion and the weight of engorged ticks, but did not affect tick feeding duration. (C) 2014 Elsevier GmbH. All rights reserved

Questing Ticks in Suburban Forest Are Infected by at Least Six Tick-Borne Pathogens

International audienceThe role of Ixodes ricinus ticks in the transmission of pathogens of public health importance such as Borrelia burgdorferi s.l. is widely recognized and is suspected in several emerging vector-borne pathogens in Europe. Here, we assess prevalence rates of several endemic and emerging zoonotic pathogens in tick populations in an area of high human population density in France, to contribute to a risk assessment for potential transmission to humans. Pathogen prevalence rates were evaluated by polymerase chain reaction detection and sequencing in questing ticks, individually for adults and in pools of 10 for nymphs. In addition to finding micro-organisms corresponding to symbionts, we found high prevalence rates of B. burgdorferi s.l. (32% of adult females and 10% of nymphs) and low to moderate ones of Anaplasma phagocytophilum (*1%), spotted fever group Rickettsia spp.(*6%), Babesia sp. EU1 (*1%), Bartonella birtlesii (0.1%), and Francisella tularensis (*1%). Our findings extend the knowledge of the geographical distribution of these endemic and emergent pathogens and support the conclusion that ticks are important vectors of pathogenic micro-organisms in suburban forests. Moreover, tick coinfection with multiple pathogens was found to occur frequently, which poses a serious challenge for diagnosis and appropriate treatment. The incrimination of these pathogens in potentially severe pathologies requires widespread surveillance to assess the risk of infection, thereby facilitating diagnosis and treatment, as well as raising local awareness of tick-borne diseases

A versatile model of hard tick infestation on laboratory rabbits

International audienceThe use of live animals in tick research is crucial for a variety of experimental purposes including the maintenance of hard tick colonies in the laboratory. In ticks, all developmental stages (except egg) are hematophagous, and acquiring a blood-meal when attached to their vertebrate hosts is essential for the successful completion of their life cycle. Here we demonstrate a simple method that uses easily openable capsules for feeding of hard ticks on rabbits. The advantages of the proposed method include its simplicity, short duration and most importantly versatile adjustment to the needs of specific experimental requirements. The method makes possible the use of multiple chambers (of various sizes) on the same animal, which permits feeding of multiple stages or different experimental groups while reducing the overall animal requirement. The non-irritating and easily accessible materials used minimizes discomfort to the animals, which can be easily recovered from an experiment and offered for adoption or reused if the ethical protocol allows it

Environmental factors influencing tick densities over seven years in a French suburban forest

International audienceWorldwide changes in socio-economic and environmental factors and the global climate are recognised causes of variation in tick distribution and density. Thus it is of great importance that new studies address the changing risk of infection for exposed populations. In Europe, Ixodes ricinus ticks are the most common vectors of several pathogens impacting veterinary and public health that have colonised suburban habitats. This study aimed to evaluate longitudinal I. ricinus questing densities and infection rates over 7 years in a French suburban forested area with high human population density. Ticks were collected in spring yearly between 2008 and 2014 and, out of a total of 8594 collected I. ricinus, a representative subset of adult females (n = 259) were individually examined for the presence of several pathogens via PCR. Nymph densities peaked in 2009-2011, and then declined in 2012-2014. Changes in monthly temperature only had a modest impact on this variation. In contrast, analysis revealed a complex intra-annual relationship between mean nymph density and both concurrent and lagged mean monthly temperatures. The following pathogens were detected in the studied area: Anaplasma phagocytophilum, Rickettsia helvetica, Babesia venatorum and B. divergens, Francisella tularensis, Borrelia miyamotoi, B. afzelii/valaisiana, B. garinii/lusitaniae and Bartonella spp. Our findings reinforce the conclusion that ticks are important vectors of pathogenic microorganisms in suburban forests and suggest that despite complex intra-annual relationships between tick densities and temperature, there is no evidence for a climate-associated increase in infection risk over the 7-year period. Rather, tick densities are likely to be strongly influenced by population density fluctuations in vertebrate host species and wildlife management. Further detailed studies on the impact of climate change on tick population densities are required

First identification of Rickettsia helvetica in questing ticks from a French Northern Brittany Forest.

International audienceTick-borne rickettsiae are considered to be emerging, but data about their presence in western Europe are scarce. Ixodes ricinus ticks, the most abundant and widespread tick species in western Europe, were collected and tested for the presence of several tick-borne pathogens in western France, a region never previously explored in this context. There was a high tick abundance with a mean of 4 females, 4.5 males, and 23.3 nymphs collected per hour per collector. Out of 622 tested ticks, specific PCR amplification showed the presence of tick symbionts as well as low prevalence of Borrelia burgdorferi (0.8%), Bartonella spp. (0.17%), and Anaplasma phagocytophilum (0.09%). The most prevalent pathogen was Rickettsia helvetica (4.17%). This is the first time that this bacteria has been detected in ticks in this region, and this result raises the possibility that bacteria other than those classically implicated may be involved in rickettsial diseases in western France