Multi-Locus Sequence Analysis Reveals Profound Genetic Diversity among Isolates of the Human Pathogen Bartonella bacilliformis

Bartonella bacilliformis is the aetiological agent of human bartonellosis, a potentially life threatening infection of significant public health concern in the Andean region of South America. Human bartonellosis has long been recognised in the region but a recent upsurge in the number of cases of the disease and an apparent expansion of its geographical distribution have re-emphasized its contemporary medical importance. Here, we describe the development of a multi-locus sequence typing (MLST) scheme for B. bacilliformis and its application to an archive of 43 isolates collected from patients across Peru. MLST identified eight sequence types among these isolates and the delineation of these was generally congruent with those of the previously described typing scheme. Phylogenetic analysis based on concatenated sequence data derived from MLST loci revealed that seven of the eight sequence types were closely related to one another; however, one sequence type, ST8, exhibited profound evolutionary divergence from the others. The extent of this divergence was akin to that observed between other members of the Bartonella genus, suggesting that ST8 strains may be better considered as members of a novel Bartonella genospecies

Occurrence and identification of risk areas of Ixodes ricinus-borne pathogens: a cost-effectiveness analysis in north-eastern Italy

<p>Abstract</p> <p>Background</p> <p><it>Ixodes ricinus</it>, a competent vector of several pathogens, is the tick species most frequently reported to bite humans in Europe. The majority of human cases of Lyme borreliosis (LB) and tick-borne encephalitis (TBE) occur in the north-eastern region of Italy. The aims of this study were to detect the occurrence of endemic and emergent pathogens in north-eastern Italy using adult tick screening, and to identify areas at risk of pathogen transmission. Based on our results, different strategies for tick collection and pathogen screening and their relative costs were evaluated and discussed.</p> <p>Methods</p> <p>From 2006 to 2008 adult ticks were collected in 31 sites and molecularly screened for the detection of pathogens previously reported in the same area (i.e., LB agents, TBE virus, <it>Anaplasma phagocytophilum, Rickettsia </it>spp., <it>Babesia </it>spp., "<it>Candidatus Neoehrlichia mikurensis</it>"). Based on the results of this survey, three sampling strategies were evaluated <it>a</it>-<it>posteriori</it>, and the impact of each strategy on the final results and the overall cost reductions were analyzed. The strategies were as follows: tick collection throughout the year and testing of female ticks only (strategy A); collection from April to June and testing of all adult ticks (strategy B); collection from April to June and testing of female ticks only (strategy C).</p> <p>Results</p> <p>Eleven pathogens were detected in 77 out of 193 ticks collected in 14 sites. The most common microorganisms detected were <it>Borrelia burgdorferi </it>sensu lato (17.6%), <it>Rickettsia helvetica </it>(13.1%), and "<it>Ca. N. mikurensis</it>" (10.5%). Within the <it>B. burgdorferi </it>complex, four genotypes (i.e., <it>B. valaisiana, B. garinii, B. afzelii</it>, and <it>B. burgdorferi </it>sensu stricto) were found. Less prevalent pathogens included <it>R. monacensis </it>(3.7%), TBE virus (2.1%), <it>A. phagocytophilum </it>(1.5%), <it>Bartonella </it>spp. (1%), and <it>Babesia </it>EU1 (0.5%). Co-infections by more than one pathogen were diagnosed in 22% of infected ticks. The prevalences of infection assessed using the three alternative strategies were in accordance with the initial results, with 13, 11, and 10 out of 14 sites showing occurrence of at least one pathogen, respectively. The strategies A, B, and C proposed herein would allow to reduce the original costs of sampling and laboratory analyses by one third, half, and two thirds, respectively. Strategy B was demonstrated to represent the most cost-effective choice, offering a substantial reduction of costs, as well as reliable results.</p> <p>Conclusions</p> <p>Monitoring of tick-borne diseases is expensive, particularly in areas where several zoonotic pathogens co-occur. Cost-effectiveness studies can support the choice of the best monitoring strategy, which should take into account the ecology of the area under investigation, as well as the available budget.</p

Is Predominant Clonal Evolution a Common Evolutionary Adaptation to Parasitism in Pathogenic Parasitic Protozoa, Fungi, Bacteria, and Viruses?

We propose that predominant clonal evolution (PCE) in microbial pathogens be defined as restrained recombination on an evolutionary scale, with genetic exchange scarce enough to not break the prevalent pattern of clonal population structure. The main features of PCE are (1) strong linkage disequilibrium, (2) the widespread occurrence of stable genetic clusters blurred by occasional bouts of genetic exchange ('near-clades'), (3) the existence of a "clonality threshold", beyond which recombination is efficiently countered by PCE, and near-clades irreversibly diverge. We hypothesize that the PCE features are not mainly due to natural selection but also chiefly originate from in-built genetic properties of pathogens. We show that the PCE model obtains even in microbes that have been considered as 'highly recombining', such as Neisseria meningitidis, and that some clonality features are observed even in Plasmodium, which has been long described as panmictic. Lastly, we provide evidence that PCE features are also observed in viruses, taking into account their extremely fast genetic turnover. The PCE model provides a convenient population genetic framework for any kind of micropathogen. It makes it possible to describe convenient units of analysis (clones and near-clades) for all applied studies. Due to PCE features, these units of analysis are stable in space and time, and clearly delimited. The PCE model opens up the possibility of revisiting the problem of species definition in these organisms. We hypothesize that PCE constitutes a major evolutionary strategy for protozoa, fungi, bacteria, and viruses to adapt to parasitism

A Gendered Faust : the portrayal of gender in the opera Faust (1859) by Gounod (1818-1893)

This thesis deconstructs the gender symbolism evident in the opera Faust (1859) by Gounod. The objective is to determine the gendered authenticity, originality and contributing nature of the work, acknowledging the Catholic nineteenth-century French context in which it was written. The study aims to establish the nature of the gender constructs portrayed (whether representative of their conservative milieu, or suggestive of unconventionality, liberalism and innovation) and how these portrayals were executed by Gounod and his librettists. An exploration of the construction of Faust and a comparison with Goethe’s Faust: Der Tragödie Erster Teil (1808), on which the Gounodian creation is loosely based, initiates the study. The theory of performativity by Judith Butler (1990), together with other general gender hypotheses on, for instance, masculine and feminine personalities and perversity, follows. Hereafter, gender in the context of artistic performances, and gender constructs in Christianity are investigated. These general, performance-based and theological theories and ideas are then compared to the gendered characters in Faust. The secular and Catholic gender norms that governed men and women in nineteenth-century France inevitably had an influence on how gender is represented in the opera. Hence, contextual aspects, as well as Gounod’s own interaction with, and exhibition of gender are analysed in order to establish their influential extent on Faust. A deconstruction of the opera as three different texts – libretto, score and DVD productions of three Faust performances – is applied since this contributes to holistic and objective conclusions. The aspects investigated in the study have brought to light that Faust shamelessly highlights the destructive consequences of social, cultural and religious gender stereotypes governing nineteenth-century Catholic France, whilst simultaneously proposing liberated gender identities. Gounod is innovative in presenting a female protagonist through the role of Marguerite. She is an intricate, developing character representative of multiple perplexed femininities, many of which are conquering and symbolic of female empowerment. Siébel serves as a source of great gender ambiguity and contradiction. These aspects are fuelled by an ironic female identity – hence, the notion of performativity is ingeniously incorporated into this character. Both femininity and masculinity is advocated in the portrayals of Méphistophèles and the Christian God, while interesting and unexpected masculinities are embodied through Faust and Valentin. By using the above methodology, I suggest that Gounod’s Faust is an authentic and pioneering work representing ambivalent, controversial, contradictory and empowering gender constructs, making it a composition of considerable worth, both musically and historically. NB: Additional information available on a CD stored at the Merensky Library front Counter.Dissertation (MMus)--University of Pretoria, Pretoria, 2013.5 CDs available with the study. Kept at the Open Scholarship Office in the Embargo room.Musicunrestricte