Search results for "Neutralization Tests"
showing 6 items of 36 documents
Plasmacytoid dendritic cells are inefficient in activation of human regulatory T cells
2011
BACKGROUND: Dendritic cells (DC) play a key role in initiation and regulation of immune responses. Plasmacytoid DC (pDC), a small subset of DC, characterized as type-I interferon producing cells, are critically involved in anti-viral immune responses, but also mediate tolerance by induction of regulatory T cells (Treg). In this study, we compared the capacity of human pDC and conventional DC (cDC) to modulate T cell activity in presence of Foxp3(+) Treg. PRINCIPAL FINDINGS: In coculture of T effector cells (Teff) and Treg, activated cDC overcome Treg anergy, abrogate their suppressive function and induce Teff proliferation. In contrast, pDC do not break Treg anergy but induce Teff prolifera…
Detection of Escherichia coli strains producing cytotoxic necrotizing factor type two (CNF2) by enzyme-linked immunosorbent assay
1994
Sheep and rabbit antisera were produced against lysates of E. coli strain 711 (pVir). This K-12 strain carries the Vir plasmid which codes for Cytotoxic Necrotizing Factor type 2 (CNF2). Immunoglobulin G (IgG) fractions of both immune sera were subsequently purified by a two-step precipitation method. To increase the specificity for CNF2, the sheep IgG preparation was extensively adsorbed against both a sonicated extract of isogenic K-12 strain 711 and intact phenol-treated cells of vaccine strain 711 (pVir). An enzyme-linked immunosorbent assay (ELISA) was developed to detect clinical isolates of E. coli producing CNF2, using the final preparations of rabbit and sheep IgG in a double sandw…
Short synthetic CDR-peptides forming the antibody combining site of the monoclonal antibody against RNA bacteriophage fr neutralize the phage activit…
1996
The construction of a mouse hybridoma FRS2 secreting neutralizing monoclonal antibody specific for RNA bacteriophages fr, MS2 and GA is reported. The genes encoding the variable domains of the monoclonal antibody FRS2 heavy and light chains were cloned and sequenced and the corresponding complementarity determining region (CDR) peptides were chemically synthesized. The CDR-peptides were tested for their ability to neutralize the activity of RNA phage fr and related RNA phages MS2 and GA. The CDR-derived peptides H2, L2 and L3 interacted with the fr phage particles and neutralized fr phage activity. Two of these peptides-H2 and L3 also had the ability to neutralize partly the activity of rel…
The role of insulin-like growth factor II in the malignant transformation of rat liver oval cells
1997
Oval cells are small nonparenchymal epithelial cells that first appear in the periportal areas of the liver and thereafter invade the whole parenchyma when mice or rats are exposed to a variety of chemical carcinogens. In the present study we have analyzed the expression of insulin-like growth factor II (IGF II) in the recently established oval cell line OC/CDE 22 and its malignantly transformed counterpart (the M22 cells) and the biological consequences of the constitutive expression of IGF II in oval cells. OC/CDE 22 cells do not express the above-mentioned growth factor, whereas the M22 cells do and addition of a neutralizing anti-IGF II antibody to M22 cells resulted in an almost comple…
Induction of Type-Specific Neutralizing Antibodies by Capsomeres of Human Papillomavirus Type 33
2001
Abstract The immunogenicity of capsomeres of human papillomavirus type 33 was evaluated in a dose–response analysis. Capsomeres were obtained free of capsids by expression of L1 carrying the single point mutation C427S. Neutralizing antibodies were detected using an in vitro pseudoinfection assay. Capsomeres induced type-specific, neutralizing antibodies in mice even in the absence of adjuvant. The neutralization titers of immune sera raised without adjuvant were 10- to 20-fold lower than those of antisera to virus-like particles, but virtually identical using Freund's adjuvant. These data indicate that capsomeres may substitute for virus-like particles in future vaccines when used with an …
Generation and neutralization of pseudovirions of human papillomavirus type 33
1997
Since human papillomaviruses (HPV) cannot be propagated in cell culture, the generation of infectious virions in vitro is a highly desirable goal. Here we report that pseudovirions can be generated by the assembly of virus-like particles (VLPs) in COS-7 cells containing multiple copies of a marker plasmid. Using recombinant vaccinia viruses, we have obtained spherical VLPs of HPV type 33 (HPV-33) which fractionate into heavy and light VLPs in cesium chloride density gradients. VLPs in the heavy fraction (1.31 g/cm3) carry the plasmid in DNase-resistant form and are capable of transferring the genetic marker located on the plasmid to COS-7 cells in a DNase-resistant way (pseudoinfection). Th…