Expression of an Epitope-Tagged Virulence Protein in Rickettsia parkeri Using Transposon Insertion

Despite recent advances in our ability to genetically manipulate Rickettsia, little has been done to employ genetic tools to study the expression and localization of Rickettsia virulence proteins. Using a mariner-based Himar1 transposition system, we expressed an epitope-tagged variant of the actin polymerizing protein RickA under the control of its native promoter in Rickettsia parkeri, allowing the detection of RickA using commercially-available antibodies. Native RickA and epitope-tagged RickA exhibited similar levels of expression and were specifically localized to bacteria. To further facilitate protein expression in Rickettsia, we also developed a plasmid for Rickettsia insertion and expression (pRIE), containing a variant Himar1 transposon with enhanced flexibility for gene insertion, and used it to generate R. parkeri strains expressing diverse fluorescent proteins. Expression of epitope-tagged proteins in Rickettsia will expand our ability to assess the regulation and function of important virulence factors

Viral epidemics in a cell culture: novel high resolution data and their interpretation by a percolation theory based model

Because of its relevance to everyday life, the spreading of viral infections has been of central interest in a variety of scientific communities involved in fighting, preventing and theoretically interpreting epidemic processes. Recent large scale observations have resulted in major discoveries concerning the overall features of the spreading process in systems with highly mobile susceptible units, but virtually no data are available about observations of infection spreading for a very large number of immobile units. Here we present the first detailed quantitative documentation of percolation-type viral epidemics in a highly reproducible in vitro system consisting of tens of thousands of virtually motionless cells. We use a confluent astroglial monolayer in a Petri dish and induce productive infection in a limited number of cells with a genetically modified herpesvirus strain. This approach allows extreme high resolution tracking of the spatio-temporal development of the epidemic. We show that a simple model is capable of reproducing the basic features of our observations, i.e., the observed behaviour is likely to be applicable to many different kinds of systems. Statistical physics inspired approaches to our data, such as fractal dimension of the infected clusters as well as their size distribution, seem to fit into a percolation theory based interpretation. We suggest that our observations may be used to model epidemics in more complex systems, which are difficult to study in isolation.Comment: To appear in PLoS ONE. Supporting material can be downloaded from http://amur.elte.hu/BDGVirus

Supplementary Material for: Dermoscopic Features of Subungual Squamous Cell Carcinoma: A Study of 44 Cases

<i>Background:</i> Subungual squamous cell carcinoma (SSCC) is the most frequent tumor of the nail apparatus. Its diagnosis is often missed or delayed because the clinical presentation is atypical and can mimic other conditions. Accurate diagnosis can only be made by performing an appropriate surgical biopsy, but biopsy is painful and often leaves definitive dystrophic scars. The use of dermoscopy, a noninvasive technique, has been described to be useful for the preoperative evaluation of nail diseases. <i>Objectives:</i> To define the different clinical and dermoscopic presentations of SSCC and to compare them with onychomatricoma-associated clinical and dermoscopic features published in our previous study. <i>Methods:</i> A retrospective review of 44 cases of SSCC seen in our institution over an 8-year period. Six observers scored 19 clinical criteria and 14 dermoscopic criteria as present or absent. Then, we compared those data to a previously published study about the preoperative diagnosis of onychomatricoma. <i>Results:</i> Only 1 dermoscopic criterion was significantly associated with SSCC compared to onychomatricoma: localized hyperkeratosis (odds ratio, OR = 6.25, <i>p</i> = 0.012, 95% confidence interval CI = 1.50-26.01). In contrast, parallel edges (OR = 0.03, <i>p</i> < 0,001, 95% CI = 0.003-0.20) and sharp demarcation of the lesion (OR = 0.24, <i>p</i> = 0.004, 95% CI = 0.09-0.63) can statistically significantly be considered as in favor of onychomatricoma. By contrast, we believe that the presence of unparalleled lateral edges of the nail lesion or of fuzzy edges are more in favor of SSCC. <i>Conclusions:</i> Dermoscopy of the nail plate and of the nail free edge in SSCC provides useful information in order to better select cases to be submitted to biopsy