Covalent coupling of HIV-1 glycoprotein trimers to biodegradable calcium phosphate nanoparticles via genetically encoded aldehyde-tags.

The usage of antigen-functionalized nanoparticles has become a major focus in the field of experimental HIV-1 vaccine research during the last decade. Various molecular mechanisms to couple native-like trimers of the HIV-1 envelope protein (Env) onto nanoparticle surfaces have been reported, but many come with disadvantages regarding the coupling efficiency and stability. In this study, a short amino acid sequence ("aldehyde-tag") was introduced at the C-terminus of a conformationally stabilized native-like Env. The post-translational conversion of a tag-associated cysteine to formylglycine creates a site-specific aldehyde group without alteration of the Env antigenicity. This aldehyde group was further utilized for bioconjugation of Env trimers. We demonstrated that the low acidic environment necessary for this bioconjugation is not affecting the trimer conformation. Furthermore, we developed a two-step coupling method for pH-sensitive nanoparticles. To this end, we conjugated aldehyde-tagged Env with Propargyl-PEG3-aminooxy linker (oxime ligation; Step-one) and coupled these conjugates by copper-catalyzed azide-alkyne cycloaddition (Click reaction; Step-two) to calcium phosphate nanoparticles (CaPs) functionalized with terminal azide groups. CaPs displaying orthogonally arranged Env trimers on their surface (o-CaPs) were superior in activation of Env-specific B-cells (in vitro) and induction of Env-specific antibody responses (in vivo) compared to CaPs with Env trimers coupled in a randomly oriented manner. Taken together, we present a reliable method for the site-specific, covalent coupling of HIV-1 Env native-like trimers to the surface of nanoparticle delivery systems. This method can be broadly applied for functionalization of nanoparticle platforms with conformationally stabilized candidate antigens for both vaccination and diagnostic approaches. STATEMENT OF SIGNIFICANCE: During the last decade antigen-functionalized nanoparticles have become a major focus in the field of experimental HIV-1 vaccines. Rational design led to the production of conformationally stabilized HIV-1 envelope protein (Env) trimers - the only target for the humoral immune system. Various molecular mechanisms to couple Env trimers onto nanoparticle surfaces have been reported, but many come with disadvantages regarding the coupling efficiency and stability. In this paper, we describe a highly selective bio-conjugation of Env trimers to the surface of medically relevant calcium phosphate nanoparticles. This method maintains the native-like protein conformation and has a broad potential application in functionalization of nanoparticle platforms with stabilized candidate antigens (including stabilized spike proteins of coronaviruses) for both vaccination and diagnostic approaches.

Assessment of a recombinant protein from Leishmania infantum as a novel tool for Visceral Leishmaniasis (VL) diagnosis in VL/HIV co-infection cases.

Visceral Leishmaniasis and HIV-AIDS coinfection (VL/HIV) is considered a life-threatening pathology when undiagnosed and untreated, due to the immunosuppression caused by both diseases. Serological tests largely used for the VL diagnosis include the direct agglutination test (DAT), ELISA and immunochromatographic (ICT) assays. For VL diagnosis in HIV infections, different studies have shown that the use of the DAT assay facilitates the VL diagnosis in co-infected patients, since the performance of the most widely used ELISA and ICT tests, based on the recombinant protein rK39, are much less efficient in HIV co-infections. In this scenario, alternative recombinant antigens may help the development of new serological diagnostic methods which may improve the VL diagnosis for the co-infection cases. This work aimed to evaluate the use of the recombinant Lci2 antigen, related to, but antigenically more diverse than rK39, for VL diagnosis in co-infected sera through ELISA assays. A direct comparison between recombinant Lci2 and rK39 was thus carried out. The two proteins were first tested using indirect ELISA with sera from VL afflicted individuals and healthy controls, with similar performances. They were then tested with two different sets of VL/HIV co-infected cases and a significant drop in performance, for one of these groups, was observed for rK39 (32% sensitivity), but not for Lci2 (98% sensitivity). In fact, an almost perfect agreement (Kappa: 0.93) between the Lci2 ELISA and DAT was observed for the coinfected VL/HIV patients. Lci2 then has the potential to be used as a new tool for the VL diagnosis of VL/HIV co-infections.

Gene design, optimization of protein expression and preliminary evaluation of a new chimeric protein for the serological diagnosis of both human and canine visceral leishmaniasis.

BACKGROUND: Visceral leishmaniasis (VL) is a major neglected disease, potentially fatal, whose control is still impaired by inefficient and/or expensive treatment and diagnostic methods. The most promising approach for VL diagnosis uses serological assays with recombinant proteins, since they are more efficient and easier to perform. Tests developed for the human form of the disease, however, have not been shown to be efficient for its diagnosis in the canine host, the major reservoir for the American VL. METHODOLOGY/PRINCIPAL FINDINGS: Here, we describe a systematic approach aimed at the production of a new chimeric protein potentially able to be used for both human and canine VL diagnosis and based both on in silico gene design and experimental data. Starting from the previous identification of Leishmania infantum recombinant antigens efficient for the diagnosis of either human or canine VL, three of the best performing antigens were selected (Lci2, Lci3 and Lci12). After a preliminary evaluation validating the chimeric approach, DNA fragments encoding predicted antigenic regions from each protein, enriched with repeats, were joined in various combinations to generate a total of seventeen chimeric genes optimized for prokaryotic expression. These were assessed for optimal expression and purification yield, with four chimeric proteins being efficiently produced. Their diagnostic potential was then evaluated through ELISA assays with sera from VL afflicted humans and dogs. After two rounds of gene design, the results showed high levels of sensitivity for the best chimeric protein, named Q5, in humans (82%) and dogs (100%) with 100% specificity in comparison with healthy controls. A single non-specific reaction was seen with serum from individuals with tegumentary leishmaniasis. CONCLUSION: The newly described chimeric protein is potentially useful for the detection of both humans and dogs afflicted with VL, with its use in rapid tests necessary for validation as a new diagnostic tool.

Performance evaluation of anti-fixed Leishmania infantum promastigotes immunoglobulin G (IgG) detected by flow cytometry as a diagnostic tool for visceral Leishmaniasis.

Visceral Leishmaniasis (VL) is a severe disease, caused by the protozoans Leishmania infantum and L. donovani that is widely diagnosed using serological tools. These, however, have limitations in performance that limit their use for the correct identification of the cases. This study aimed to evaluate the performance of flow cytometry with fixed parasites for VL diagnosis, comparing it with four other serological tests. Samples from two endemic VL regions in Brazil, diagnosed by direct examination (DG1) and by at least two or one standard serological test (DG2 and DG3, respectively), as well as patients with chronic Chagas' disease (CG1) and healthy controls (CG2) were used in this study. The flow cytometry results were expressed as levels of IgG reactivity, based on the percentage of positive fluorescent parasites (PPFP). Using a 1:4096 serum dilution, a ROC curve analysis of the serum titration on flow cytometry has indicated a PPFP of 2% as the cutoff point to segregate positive and negative results. In the present study, flow cytometry had the best performance for DG1 (sensitivity of 96%) while rK39 (imunocromagraphic rapid test) and DAT (Direct agglutination test) were also associated with high sensitivity and specificity. The substantial agreement and kappa indexes observed suggested similar performances between these two tests and flow cytometry. IFAT (Immunofluorescent antibody test) and ELISA (Enzyme-linked immunosorbent assay) had lower performances and the lower values of agreement with flow cytometry. Together, these findings suggest that although adjustments are needed in order to reduce cross reactivity with other trypanosomatids, flow cytometry has the potential to be a safe serological alternative for the diagnosis of VL.

Evaluation of a new set of recombinant antigens for the serological diagnosis of human and canine visceral leishmaniasis.

Current strategies for the control of zoonotic visceral leishmaniasis (VL) rely on its efficient diagnosis in both human and canine hosts. The most promising and cost effective approach is based on serologic assays with recombinant proteins. However, no single antigen has been found so far which can be effectively used to detect the disease in both dogs and humans. In previous works, we identified Leishmania infantum antigens with potential for the serodiagnosis of VL. Here, we aimed to expand the panel of the available antigens for VL diagnosis through another screening of a genomic expression library. Seven different protein-coding gene fragments were identified, five of which encoding proteins which have not been previously studied in Leishmania and rich in repetitive motifs. Poly-histidine tagged polypeptides were generated from six genes and evaluated for their potential for diagnosis of VL by ELISA (Enzyme Linked ImmunoSorbent Assay) with sera from infected humans and dogs. None of those was valid for the detection of human VL (26-52% sensitivity) although their performance was increased in the canine sera (48-91% sensitivity), with one polypeptide useful for the diagnosis of canine leishmaniasis. Next, we assayed a mixture of three antigens, found to be best for human or canine VL, among 13 identified through different screenings. This "Mix" resulted in similar levels of sensitivity for both human (84%) and canine (88%) sera. With improvements, this validates the use of multiple proteins, including antigens identified here, as components of a single system for the diagnosis of both forms of leishmaniasis.

Interviewing children about real and fictitious events: revisiting the narrative elaboration procedure.

Elementary school children participated in a staged event. Two weeks later they were randomly assigned to three interview conditions: (a) a streamlined version of the Narrative Elaboration (NE) procedure involving training in the use of reminder cue cards, (b) exposure to reminder cue cards without training in their use (cue card control group), and (c) a standard interview including no NE training or exposure to reminder cue cards (standard-interview control group). Children in each interview condition were questioned about the staged event and a fictitious event to determine whether children trained in the streamlined NE procedure would provide more information about a staged event than would children in the two control groups and whether the NE interview would result in increased reporting of false information when questioned about a fictitious event. Results indicated that children questioned with the NE interview reported a greater amount of accurate, but not a greater amount of inaccurate, information during cue-card presentation for the staged event than did the cue-card control group. Analyses further indicated that the NE-interview group did not report significantly more false information about the fictitious event than did children in the two control groups. Large standard deviations for the NE-interview children's cue-card recall indicate that the streamlined NE procedure was useful for many children in reporting the staged event, but may have contributed to a small number of children providing false information for the fictitious event. Further research is being conducted to determine which children may be more likely to be helped and which children may be more likely to provide false information regarding a fictitious event.

Glutamate dehydrogenase, the marker protein of Plasmodium falciparum--cloning, expression and characterization of the malarial enzyme.

The gene of an NADP+-specific glutamate dehydrogenase was cloned from Plasmodium falciparum, the causative agent of tropical malaria. Southern-blot analysis indicates a single-copy gene. The gene encodes a protein with 470 residues which has 50% of all residues identical with those of the glutamate dehydrogenases from other low eukaryotes and eubacteria. In contrast, the sequence identity with the human enzyme is marginal, which underlines the long evolutionary distance between parasite and host. The gene was overexpressed in Escherichia coli. The kinetic properties of the recombinant enzyme are in good agreement with those of the authentic enzyme. The parasite enzyme is inhibited by D-glutamate and glutarate, but not by chloroquine. Like other coenzyme-specific glutamate dehydrogenases, but in contrast to the dual-specific mammalian enzymes, the P. falciparum enzyme is not affected by GTP and ADP. The physical and chemical properties of the protein are in accordance with the cytosol being the major localization. The gene does not encode a cleavable mitochondrial presequence and the Mr of the recombinant protein and the protein isolated from the parasite are indistinguishable on SDS/PAGE. Western-blot analysis of stage-specific parasites shows that glutamate dehydrogenase is present in all intraerythrocytic stages. The signal increased continuously from rings, early trophozoites to late trophozoites and decreased slightly in the segmenter stage. Glutamate dehydrogenase, suggested to be the major source of NADPH in the parasite, is an attractive target molecule for the rational development of new antimalarial drugs.

A perspective from clinical and business ethics on adverse events in hospitalized patients.

Adverse events occur in a significant, but undetermined, number of hospitalized patients. These types of patient injuries are more often the result of faulty systems than human maleficence. A culture exists among health care providers that discourages the reporting of such events and resists the implementation of formal efforts to eliminate them. This resistance serves to perpetuate the problem. Both business and clinical ethics argue that sound reasons exist for hospitals to reduce, if not eliminate, adverse events. To do so is cost effective, particularly in a managed care environment. It is also at the heart of responsible professional behavior. Physicians are afforded an opportunity to be at the forefront in this quality improvement effort.

Spiritual issues and bioethics in the intensive care unit: the role of the chaplain.

This article familiarizes the reader with the contributions of a hospital chaplain regarding spiritual and ethical issues in the intensive care unit. The unique training and perspective of the hospital chaplain are reviewed to explain how the chaplain and the parish minister compare. Cases are presented to illustrate how the chaplain functions, and specific topics of concern that relate bioethical issues with spiritual issues, such as organ donation, are addressed. Faith in "miracles" is discussed within a framework for interpreting religious ideation, particularly when belief prolongs death.

Posterior tibial tendon rupture: classification, modified surgical repair, and retrospective study.

Posterior tibial tendon rupture is often misdiagnosed. The authors have presented a retrospective study of a new variation to the repair of this tendon. The anatomy, physiology, etiology, clinical manifestations, radiographic and magnetic resonance imaging, and historical methods are reviewed. A classification scheme based on location and appearance is discussed. A review of 17 cases was performed with results of 88% pain relief following the discussed procedure.

Neonatal ethics: development of a consultative group.

Experience of a neonatal ethics advisory group in a tertiary care setting was reviewed to identify which aspects of the experience have been most valuable in the development of a consultative group. Consultations were requested for 31 patients seen from August 1984 through December 1988. Review of these patients indicated that 21 of 31 infants were born after full-term gestations, 11 of 31 infants were seen beyond the neonatal period, and some type of congenital anomaly was the principal diagnosis for 64.7% of the patients. The reasons for seeking consultation primarily involved decisions regarding withdrawal or withholding of treatment. For 22 of the 31 patients, the consensus of the group supported the decision of the health care team. In the remaining consultations, the recommendation of the group was that more information and/or communication was needed. In the analysis of the neonatal ethics advisory group's experience with consultations the characteristics of neonatal patients were identified and the value of having a forum for discussing the difficult ethical issues facing members of the health care team were validated.

A leaderless approach to a minister's peer-support group.

This article describes a support group for ministers that uses a leaderless approach. The group has met for over ten years and as a result of that experience has developed in ways that make it unique. These group characteristics are described and are offered as a general guide for ministers as well as members of other helping professions who are interested in peer support.

Rapping with a chaplain.

Group discussions for senior physical therapy students, led by the hospital chaplain, were held at the University of Florida Medical Center. The idea for these "rap sessions" originated with the Department of Physical Therapy at Shands Teaching Hospital. The content of the discussions grew out of the students' experiences during their clinical assignments. The experience was deemed beneficial to the learning process by students, clinic staff, and faculty and helped to create a more relaxed atmosphere for learning in the clinic.