Towards cellular receptors for prions

Transmissible spongiform encephalopathies (TSE) are attributed to the conversion of the cellular prion protein (PrP(c)) into an abnormal isoform (PrP(sc)). This can be caused by the invasion of living organisms by infectious particles, or be inherited due to mutations on the PrP(c) gene. One of the most intriguing problems of prion biology is the inability to generate the infectious agent in vitro. This argues strongly that other cellular proteins besides those added in test tubes or found in cellular preparations are necessary for infection. Despite recent progress in the understanding of prion pathology, the subcellular compartments in which the interaction and conversion of PrP(c) into PrP(sc) take place are still controversial. PrP(c) interacts with various macromolecules at the cell membrane, in endocytic compartments and in the secretory pathway, all of which may play specific roles in the internalisation of PrP(sc) and conversion of PrP(c). A specific interacting protein required for the propagation of prions was originally proposed as a prion receptor, and later referred to as a ligand, a cofactor, protein X, or a partner. However, current studies indicate that PrP(c) associates with multi-molecular complexes, which mediate a variety of functions in distinct cellular compartments. It is proposed that a deeper understanding of the mechanics of such interactions, coupled to a better knowledge of the corresponding signalling pathways and ensuing cellular responses, will have a major impact on the prevention and treatment of TSE.     

Interleukin-12 mediates resistance to Trypanosoma cruzi in mice and is produced by murine macrophages in response to live trypomastigotes.

Host resistance to infection by Trypanosoma cruzi is dependent on both natural and acquired immune responses. During the first week of infection in mice, NK cell-derived gamma interferon (IFN-gamma) is involved in controlling intracellular parasite replication, mainly through the induction of NO biosynthesis by activated macrophages. Interleukin-12 (IL-12) has been shown to be a powerful cytokine in inducing IFN-gamma synthesis by NK cells, as well as in mediating resistance to different intracellular protozoa. We have therefore studied the ability of T. cruzi to elicit IL-12 synthesis by macrophages and the role of this cytokine in controlling parasite replication during acute infection in mice. Our results show that macrophages cultured in the presence of live trypomastigote forms (but not epimastigotes) release IL-12 that can induce IFN-gamma production by normal spleen cells. IL-12 was detected in as little as 12 h after the addition of the trypomastigotes, and the level of IL-12 peaked at 48 h after the initial macrophage-parasite incubation. The addition of anti-IL-12 monoclonal antibody to macrophage-trypomastigote supernatants dose-dependently inhibited IFN-gamma production by naive splenocytes. Finally, the in vivo role of IL-12 in resistance to infection by T. cruzi was analyzed. Mice treated with anti-IL-12 monoclonal antibody had significantly increased parasitemia and mortality in comparison with those of control infected mice treated with control antibody. Together, these results suggest that macrophage-derived IL-12 plays a major role in controlling the parasitemia in T. cruzi-infected mice and that the animal's resistance during the acute phase of infection may, at least in part, be a consequence of postinfection levels of IL-12.     

Local and systemic antibody class responses to an infectious laryngotracheitis virus vaccine strain

Chickens infected with infectious laryngotracheitis virus (ILTV) responded by producing virus-specific IgG in their sera, which increased steadily in concentration, but with slight fluctuations, until peak titres were reached 40 days post-inoculation (pi), immediately prior to the second challenge. Thereafter, following an initial lag, concentrations continued to increase for 21 days before falling slightly at the end of the experiment. In contrast, peak concentrations of ILTV-specific IgM were reached 6 days pi falling to their lowest levels by day 16, before increasing to a second peak and trough on days 26 and 32, respectively. This cyclical production of ILTV-specific IgM was confirmed in a second experiment. The pattern of production of ILTV-specific IgG, IgM and IgA, detected in tracheal washings, occurred in the same cyclical manner. IgM was produced first, peak concentrations being detected 5 days pi, whereas IgG and IgA did not peak until 10 days pi, with second peaks of each class being detected 25-30 days pi. The possibility that the cyclical antibody class response to ILTV infection is related to the previously reported intermittent pattern of re-excretion of the virus is discussed.     

Group‐specific component (GC) in curiaú and pacoval,two african‐derived brazilian populations

The group‐specific component (GC) system is of interest in anthropological genetic studies because the distribution of its subtypes distinguishes among major ethnic groups. The GC system was analyzed in Curiaú and Pacoval, two remnant Quilombo populations (African‐derived populations) from the Brazilian Amazon. There was no significant statistical difference in allelic frequencies between the two populations or between them and three other African‐derived Brazilian populations (Mimbó, Sítio Velho, and Gaucinha in Northeastern Brazil). These populations share similarities among themselves and with African populations (high frequencies of GC*1F and lower frequencies of GC*1S), which may reflect the influence of a high level of African contribution to their formation, but there is a clear difference between them and Europeans and South American Indians. It is suggested that the GC system is a useful marker for studying relationships between single populations and major ethnic groups, but does not discriminate between populations which share the same parental stock. Am. J. Hum. Biol. 13:718–720, 2001. © 2001 Wiley‐Liss, Inc.     

DADOS-Survey: an open-source application for CHERRIES-compliant Web surveys

Background  

The Internet has been increasingly utilized in biomedical research. From online searching for literature to data sharing, the Internet has emerged as a primary means of research for many physicians and scientists. As a result, Web-based surveys have been employed as an alternative to traditional, paper-based surveys. We describe DADOS-Survey, an open-source Web-survey application developed at our institution that, to the best of our knowledge, is the first to be compliant with the Checklist for Reporting Results of Internet E-Surveys (CHERRIES). DADOS-Survey was designed with usability as a priority, allowing investigators to design and execute their own studies with minimal technical difficulties in doing so.     

Experimental autoimmune encephalomyelitis can be prevented and cured by infection with Trypanosoma cruzi

Trypanosoma cruzi is an intracellular parasite that induces a strong Th1-type response and immunosuppression during the acute phase of infection. To study how the infection with T. cruzi would modulate the development of an autoimmune disease, we immunized C57BL/6 mice and IL-10 or iNOS knock-out mice of the same background with the encephalitogenic MOG 35-55 peptide and infected them with T. cruzi. Our results demonstrate that infection with T. cruzi completely prevents EAE development and furthermore induces complete and lasting remission in mice that were infected with this parasite after they had developed clinical EAE. Nitric oxide and IL-10 participate in triggering the mechanisms associated with EAE suppression by the infection. Decreased lymphoproliferation and increased frequencies of Annexin-positive cells and of T cells bearing CD95, CD95L or CTLA-4 were observed in the spleen from immunized/infected mice, as well as lower IL-2 and increased TGF-beta production in comparison with only immunized mice. Our results indicate that several effector and regulatory mechanisms of the immune response that arise during the acute phase of T. cruzi infection lastingly affect the expansion and/or effector functions of encephalitogenic cells, preventing the onset or inducing complete remission of EAE.     

Evaluations of commercial West Nile virus immunoglobulin G (IgG) and IgM enzyme immunoassays show the value of continuous validation

West Nile virus was introduced into the United States in 1999 and in only four seasons has become endemic east of the Rocky Mountains. Recently, immunoglobulin M (IgM)-capture enzyme immunoassays for the detection of West Nile virus-specific IgM and indirect IgG enzyme immunoassays for the detection of IgG antibodies against West Nile virus were made available from Focus Technologies and PANBIO, Inc. We evaluated these commercial IgG and IgM test systems and determined agreement, sensitivity, and specificity for the assays, compared to immunofluorescence assay and the Centers for Disease Control and Prevention's IgM-capture enzyme-linked immunosorbent assay (ELISA). Initially, the Focus and PANBIO IgM enzyme immunoassays had at least 95% agreement, sensitivity, and specificity, and, based on the 95% confidence intervals, both IgM-capture assays performed similarly. The IgG assays also performed well, although the Focus IgG assay demonstrated greater specificity (98.8%) and the PANBIO IgG assay demonstrated greater sensitivity (99.3%). However, for 400 samples consecutively submitted for West Nile virus antibody testing during 2 days of the 2003 West Nile virus season, agreement, clinical sensitivity, and clinical specificity were 93.1, 98.0, and 92.4%, respectively, for the PANBIO IgM assay and were 97.4, 100.0, and 97.1%, respectively, for the Focus IgM assay. The specificities observed in this second evaluation equates to an overall false-positivity rate of 6.3% in the PANBIO West Nile virus IgM-capture ELISA versus 2.5% with the Focus West Nile virus IgM-capture ELISA. This experience demonstrates the importance of continuously evaluating the performance of an assay in order to detect any changes in assay performance as the test population evolves.     

Duke Surgery Research Central: an open-source Web application for the improvement of compliance with research regulation

Background  

Although regulatory compliance in academic research is enforced by law to ensure high quality and safety to participants, its implementation is frequently hindered by cost and logistical barriers. In order to decrease these barriers, we have developed a Web-based application, Duke Surgery Research Central (DSRC), to monitor and streamline the regulatory research process.     

The Helix aspersa (brown garden snail) allergen repertoire

BACKGROUND: Ingestion of snails can induce strong asthmatic or anaphylactic responses, mainly in house-dust-mite-sensitized patients. The aim of this study was to identify the Helix aspersa (Hel a), Theba pisana (The p) and Otala lactea (Ota l) allergens and the extent of their cross-reactivity with the Dermatophagoides pteronyssinus (Der p) mite. PATIENTS AND METHODS: In 60 atopic patients, skin prick tests (SPT) to snail and D. pteronyssinus, total and specific IgE, specific IgE immunoblots, RAST and immunoblot inhibition assays were performed. RESULTS: Mean total IgE was >1,000 kU/l. Mean specific IgE (class 6 for Der p and class 2 for Hel a) SPT were positive in 44 patients for snail and in 56 for mite. Isoelectric focusing (IEF) and SDS-PAGE followed by immunoblotting of H. aspersa extract enabled the identification of 27 and 20 allergens, respectively. Myosin heavy chains from snails (molecular weight >208 kDa) disclosed two major allergens. Hel a and Der p RAST were strongly inhibited by their homologous extracts, with Hel a RAST being inhibited by the Der p extract to a much greater extent (72.6%) than the inverse (5.6%). A complete inhibition of the immunoblots by their homologous extract was obtained. However, Hel a extract did not inhibit Der p IEF separated recognition. On the other hand, mite extract extensively inhibited snail immunoblots from both IEF and SDS-PAGE separations. Immune detection on chicken, pig, rabbit, cow and horse myosins did not reveal any IgE cross recognition with snail. CONCLUSIONS: In most cases of snail allergy, mite appeared to be the sensitizing agent. Nevertheless, snails may also be able to induce sensitization by themselves. This hypothesis is supported by the finding of specific IgE to Hel a in 2 patients who did not show specific IgE to Der p, and one of them was suffering from asthma after snail ingestion.