CD4+ Lymphocytes and Gamma Interferon Predominate in Local Immune Responses in Early Experimental Syphilis▿

The clearance of Treponema pallidum subsp. pallidum from early syphilis lesions involves infiltration of a large number of mononuclear cells and is characteristic of a cell-mediated immune response. In the present study, we sought to determine the relative abundance of different T-lymphocyte populations and Th1/Th2-associated cytokines present in testicular lesions following experimental infection with the Chicago strain of T. pallidum. Using flow cytometry, we examined the proportion of CD4+ and CD8+ T cells present throughout the progression and resolution of primary syphilis in the rabbit model. We related these findings to the results of real-time reverse transcription-PCR quantification of treponemal and cytokine mRNA levels. Treponemal mRNA levels reached peak values on day 18 postinfection, coincident with an initial peak in the level of T cells, which were primarily CD4+ T cells. T-cell levels increased again during resolution of orchitis, and there was an increased proportion of CD8+ T cells. The maximum gamma interferon (IFN-γ) and interleukin-10 (IL-10) mRNA levels were observed on days 11 and 18, respectively, while only negligible amounts of IL-4 and IL-2 were detected throughout the infection. In addition to showing the temporal relationship between treponemal burden and T-cell responses during lesion progression, our results also demonstrate that the composition of the T-cell population changes during lesion resolution. The presence of the mRNA for IFN-γ, but not IL-4, is consistent with cytokine expression in human syphilis and provides further support for the hypothesis that there is a Th1 predominance during the early immune response to T. pallidum

High-Throughput Molecular Determination of Salmonella enterica Serovars by Use of Multiplex PCR and Capillary Electrophoresis Analysis▿

Salmonella enterica is a leading cause of food-borne illness worldwide and is also a major cause of morbidity and mortality in domestic and wild animals. In the current study, a high-throughput molecular assay was developed to determine the most common clinical and nonhuman serovars of S. enterica in the United States. Sixteen genomic targets were identified based on their differential distribution among common serovars. Primers were designed to amplify regions of each of these targets in a single multiplex PCR while incorporating a 6-carboxyfluorescein-labeled universal primer to fluorescently label all amplicons. The fluorescently labeled PCR products were separated using capillary electrophoresis, and a Salmonella multiplex assay for rapid typing (SMART) code was generated for each isolate, based upon the presence or absence of PCR products generated from each target gene. Seven hundred fifty-one blind clinical isolates of Salmonella from Washington State, collected in 2007 and previously serotyped via antisera, were screened with the assay. A total of 89.6% of the isolates were correctly identified based on comparison to a panel of representative SMART codes previously determined for the top 50 most common serovars in the United States. Of the remaining isolates, 6.2% represented isolates that produced a new SMART code for a previously determined serotype, while the final 8.8% were from serotypes not screened in the original panel used to score isolates in the blinded study. This high-throughput multiplex PCR assay allowed simple and accurate typing of the most prevalent clinical serovars of Salmonella enterica at a level comparable to that of conventional serotyping, but at a fraction of both the cost and time required per test

Antibody Responses Elicited against the Treponema pallidum Repeat Proteins Differ during Infection with Different Isolates of Treponema pallidum subsp. pallidum

Variation in the expression of the different Tpr proteins in the syphilis spirochete, Treponema pallidum subsp. pallidum, may have important implications in its ability to evade host immune detection and cause persistent infection. In the present study we examined the pattern of antibody responsiveness to different Tpr members during infection with three isolates of T. pallidum. There was variability in the specificities and temporal patterns of reactivity of the antibodies elicited against the individual Tpr proteins, suggesting that isolates may express different repertoires of Tpr proteins during infection

Diagnostic Tests to Support Late-Stage Control Programs for Schistosomiasis and Soil-Transmitted Helminthiases

<div><p>Global efforts to address schistosomiasis and soil-transmitted helminthiases (STH) include deworming programs for school-aged children that are made possible by large-scale drug donations. Decisions on these mass drug administration (MDA) programs currently rely on microscopic examination of clinical specimens to determine the presence of parasite eggs. However, microscopy-based methods are not sensitive to the low-intensity infections that characterize populations that have undergone MDA. Thus, there has been increasing recognition within the schistosomiasis and STH communities of the need for improved diagnostic tools to support late-stage control program decisions, such as when to stop or reduce MDA. Failure to adequately address the need for new diagnostics could jeopardize achievement of the 2020 London Declaration goals. In this report, we assess diagnostic needs and landscape potential solutions and determine appropriate strategies to improve diagnostic testing to support control and elimination programs. Based upon literature reviews and previous input from experts in the schistosomiasis and STH communities, we prioritized two diagnostic use cases for further exploration: to inform MDA-stopping decisions and post-MDA surveillance. To this end, PATH has refined target product profiles (TPPs) for schistosomiasis and STH diagnostics that are applicable to these use cases. We evaluated the limitations of current diagnostic methods with regards to these use cases and identified candidate biomarkers and diagnostics with potential application as new tools. Based on this analysis, there is a need to develop antigen-detecting rapid diagnostic tests (RDTs) with simplified, field-deployable sample preparation for schistosomiasis. Additionally, there is a need for diagnostic tests that are more sensitive than the current methods for STH, which may include either a field-deployable molecular test or a simple, low-cost, rapid antigen-detecting test.</p></div

The steps required for gold standard microscopy in deworming programs.

<p>In the typical surveillance testing performed to assess the prevalence of helminth infection and the impact of deworming programs, stool samples (or sometimes urine for schistosomiasis) are collected and transported to a nearby laboratory space for microscopic analysis and follow-on reporting. There are numerous factors affecting each step of the process that contribute to making this analysis less than optimal.</p

Overview of STH and Schistosomaiasis (SCH) diagnostic landscapes.

<p>Overview of STH and Schistosomaiasis (SCH) diagnostic landscapes.</p

Recombinant human G6PD for quality control and quality assurance of novel point-of-care diagnostics for G6PD deficiency.

BACKGROUND:A large gap for the support of point-of-care testing is the availability of reagents to support quality control (QC) of diagnostic assays along the supply chain from the manufacturer to the end user. While reagents and systems exist to support QC of laboratory screening tests for glucose-6-phosphate dehydrogenase (G6PD) deficiency, they are not configured appropriately to support point-of-care testing. The feasibility of using lyophilized recombinant human G6PD as a QC reagent in novel point-of-care tests for G6PD deficiency is demonstrated. METHODS:Human recombinant G6PD (r-G6PD) was expressed in Escherichia coli and purified. Aliquots were stored at -80°C. Prior to lyophilization, aliquots were thawed, and three concentrations of r-G6PD (representing normal, intermediate, and deficient clinical G6PD levels) were prepared and mixed with a protective formulation, which protects the enzyme activity against degradation from denaturation during the lyophilization process. Following lyophilization, individual single-use tubes of lyophilized r-G6PD were placed in individual packs with desiccants and stored at five temperatures for one year. An enzyme assay for G6PD activity was used to ascertain the stability of r-G6PD activity while stored at different temperatures. RESULTS:Lyophilized r-G6PD is stable and can be used as a control indicator. Results presented here show that G6PD activity is stable for at least 365 days when stored at -80°C, 4°C, 30°C, and 45°C. When stored at 55°C, enzyme activity was found to be stable only through day 28. CONCLUSIONS:Lyophilized r-G6PD enzyme is stable and can be used as a control for point-of-care tests for G6PD deficiency

Stability of the reconstituted lyophilized recombinant glucose-6-phosphate dehydrogenase (r-G6PD).

<p>Lyophilized controls were reconstituted under four conditions to determine stability after rehydration. Three concentrations were assessed: normal (blue), high intermediate (purple), and intermediate (green). The controls were rehydrated in protein storage buffer (PSB) or deionized (DI) water and kept on ice or at room temperature after rehydration: PSB on ice (filled squares), PSB at room temperature (filled circles), DI water on ice (filled triangles), and DI water at room temperature (filled diamonds). Activity was measured on the Trinity Biotech quantitative assay at time zero, 1 hour, 2 hours, 4 hours, 6 hours, 8 hours, and overnight 24 hours later. Thresholds are shown to indicate whether each measurement is still within an acceptable range of G6PD enzyme activity based on the ranges of Trinity controls: lower acceptable normal (blue dotted line), upper intermediate (black dotted line), lower intermediate (green dotted line), and upper deficient (red dotted line).</p

Titration of lyophilized human recombinant glucose-6-phosphate dehydrogenase (r-G6PD).

<p>Lyophilized human r-G6PD (blue line) was titrated and tested in the Trinity Biotech quantitative assay alongside the Trinity controls (grey line). From these data, three lyophilized concentrations were chosen to represent normal, intermediate, and deficient enzyme activity.</p

Workflow for the use of the lyophilized control with a glucose-6-phosphate dehydrogenase (G6PD) rapid diagnostic test.

<p>Workflow for the use of the lyophilized control with a glucose-6-phosphate dehydrogenase (G6PD) rapid diagnostic test.</p