Serological correlate of protection against norovirus-induced gastroenteritis

Norovirus infection is the leading cause of acute nonbacterial gastroenteritis. Histoblood group antigens (HBGAs) are host susceptibility determinants for Norwalk virus (NV) infection. We hypothesized that antibodies that block NV-HBGA binding are associated with protection from clinical illness following NV exposure.

Comparison of techniques to screen and characterize bacteria-specific hybridomas for high-quality monoclonal antibodies selection

Antibodies are are very important materials for diagnostics. A rapid and simple hybridoma screening method will help in delivering specific monoclonal antibodies. In this study, we systematically developed the first antibody array to screen for bacteria-specific monoclonal antibodies using Listeria monocytogenes as a bacteria model. The antibody array was developed to expedite the hybridoma screening process by printing hybridoma supernatants on a glass slide coated with an antigen of interest. This screening method is based on the binding ability of supernatants to the coated antigen. The bound supernatants were detected by a fluorescently labeled anti-mouse immunoglobulin. Conditions (slide types, coating, spotting, and blocking buffers) for antibody array construction were optimized. To demonstrate its usefulness, antibody array was used to screen a sample set of 96 hybridoma supernatants in comparison to ELISA. Most of the positive results identified by ELISA and antibody array methods were in agreement except for those with low signals that were undetectable by antibody array. Hybridoma supernatants were further characterized with surface plasmon resonance to obtain additional data on the characteristics of each selected clone. While the antibody array was slightly less sensitive than ELISA, a much faster and lower cost procedure to screen clones against multiple antigens has been demonstrated. (C) 2011 Elsevier Inc. All rights reserved.

Fasciola hepatica:development of monoclonal antibodies and their use to characterize a glycocalyx antigen in migrating flukes

Using mice harbouring early Fasciola hepatica infections, six monoclonal antibodies were prepared against a tegumental antigen present in T1 granules and glycocalyx of flukes. Blocking tests indicated that all monoclonals bound the same T1 epitope (or epitopes in close proximity on the antigen molecule), but this was not the determinant recognized by sheep and cattle. Localization of antibody binding at light and electron microscope levels showed that T1-type antigen also occurred in metacercarial tegument and in glycocalyx of gut cells and excretory ducts in juvenile and adult flukes. This indicates that the natural host-antibody response to F. hepatica may be to one antigen early in the infection. Protein A-gold labelling of monoclonal treated fluke sections revealed that the epitope was probably a polypeptide, unmodified by glycosylation in Golgi bodies. When isolated by immunoadsorption and separated electrophoretically under reducing conditions T1-type antigen was found to consist of a polypeptide mol. wt. 50 000, possibly linked to smaller entities mol. wt. 25-40 000. Tissue-specific variations in the antigen molecule might be conferred by linkage of different polypeptides or carbohydrate side-chains to an antigenic core polypeptide. A component of T1-type antigen was found to have mol. wt. of 25 000, possibly resembling a polypeptide of mol. wt. 24 000 from Schistosoma mansoni tegument.

Studies of Microthrix parvicella in situ and in laboratory culture: production and use of specific antibodies

Physiological studies on M. parvicella have been conducted to determine the rate of growth of this organism in pure culture. The organism displayed a doubling time of 128 days despite its profuse abundance in a local Wastewater Treatment Plant (WWTW). An extensive survey has been ongoing since February 2000 into the extent of M. parvicella in the WWTW. A suite of monoclonal and polyclonal antibodies has been developed to detect and quantify M. parvicella.

Chondrogenic Differentiation Alters the Immunosuppressive Property of Bone Marrow-Derived Mesenchymal Stem Cells, and the Effect is Partially due to the Upregulated Expression of B7 Molecules

To investigate the immunosuppressive properties of mesenchymal stem cells (MSCs), in the present study we examined the immunogenicity of undifferentiated and tri-lineage (chondrocytes, osteoblasts and adipocytes) differentiated rat bone marrow-derived MSCs under xenogeneic conditions. After chondrogenic-differentiation, rat bone marrow-derived MSCs stimulated human peripheral blood monocyte-derived DCs (hDCs), leading to 8- and 4-fold higher lymphocyte proliferation and cytotoxicity than that of undifferentiated MSCs. The Chondrogenic-differentiated MSCs were chemotactic to hDCs in Dunn chamber chemotaxis system and were rosetted by hDCs inrosette assays. Flow cytometry analysis revealed that chondrogenic-differentiated MSCs had promoted hDCs maturation causing higher CD83 expression in hDCs, whereas undifferentiated MSCs, osteogenic-and adipogenic-differentiated MSCs showed inhibitory effect on hDCs maturation. The co-stimulatory molecules B7 were up-regulated only in the chondrogenic-differentiated MSCs. After blocking B7 molecules with specific monoclonal antibodies in the chondrogenic-differentiated MSCs, CD83 expression of co-cultured hDCs was greatly reduced. In conclusion, chondrogenic differentiation may increase the immunogenicity of MSCs, leading to stimulation of DCs. The up-regulated expression of B7 molecules on the chondrogenic differentiated MSCs may be partially responsible for this event.

Molecular cloning of a novel putative potassium channel-blocking neurotoxin from the venom of the North African scorpion, Androctonus amoreuxi

Scorpion venoms are a particularly rich source of neurotoxic proteins/peptides that interact in a highly specific fashion with discrete subtypes of ion channels in excitable and non-excitable cells. Here we have employed a recently developed technique to effect molecular cloning and structural characterization of a novel putative potassium channel-blocking toxin from the same sample of venom from the North African scorpion, Androctonus amoreuxi. The deduced precursor open-reading frame is composed of 59 amino acid residues that consists of a signal peptide of approximately 22 amino acid residues followed by a mature toxin of 37 amino acid residues. The mature toxin contains two functionally important residues (Lys27 and Tyr36), constituting a functional dyad motif that may be critical for potassium channel-blocking activity that can be affirmed from structural homologs as occurring in the venoms from other species of Androctonus scorpions. Parallel proteomic/transcriptomic studies can thus be performed on the same scorpion venom sample without sacrifice of the donor animal.