Two monoclonal antibodies (MAbs) against the ORF2 protein of the SAR-55 strain of hepatitis E virus (HEV) were isolated by phage display from a cDNA library of chimpanzee (Pan troglodytes) ␥1/ antibody genes. Both MAbs, HEV#4 and HEV#31, bound to reduced, denatured open reading frame 2 (ORF2) protein in a Western blot, suggesting that they recognize linear epitopes. The affinities (equilibrium dissociation constants, K d ) for the SAR-55 ORF2 protein were 1.7 nM for HEV#4 and 5.4 nM for HEV#31. The two MAbs also reacted in an enzyme-linked immunosorbent assay with recombinant ORF2 protein from a heterologous HEV, the Meng strain. Each MAb blocked the subsequent binding of the other MAb to homologous ORF2 protein in indirect competition assays, suggesting that they recognize the same or overlapping epitopes. Radioimmunoprecipitation assays suggested that at least part of the linear epitope(s) recognized by the two MAbs is located between amino acids 578 and 607. MAbs were mixed with homologous HEV in vitro and then inoculated into rhesus monkeys (Macaca mulatta) to determine their neutralizing ability. Whereas all control animals developed hepatitis (elevated liver enzyme levels in serum) and seroconverted to HEV, those receiving an inoculum incubated with either HEV#4 or HEV#31 were not infected. Therefore, each MAb neutralized the SAR-55 strain of HEV in vitro.Hepatitis E is an acute disease endemic in many countries throughout developing parts of the world, in particular on the continents of Africa and Asia, where epidemics have also occurred. The causative agent, hepatitis E virus (HEV), is transmitted via the fecal-oral route, predominantly through contaminated water (45). HEV is an RNA virus with a positive-sense genome approximately 7.5 kb in length. The genome contains three open reading frames (ORFs); ORF2 encodes the putative capsid protein (45). Hepatitis E has a low mortality rate in young adults (38). However, mortality rates can reach 20% in women in the third trimester of pregnancy (32, 58). Surprisingly, in industrialized countries such as the United States, where hepatitis E is not endemic, a significant proportion of healthy individuals within the general population are seropositive (over 20% in some areas; 39, 50). However, clinical hepatitis E is rare in these countries and usually is seen in individuals who acquired the infection during travel to a region in which HEV is endemic or epidemic.It has been suggested that animals serve as reservoirs for HEV and that human infections may, in part, be zoonoses. There have been several reports of HEV-specific (anti-HEV) antibody in animals (1, 9, 28, 29). Furthermore, an HEV-like virus was recently isolated from naturally infected swine in the United States (40). Although four genotypes of HEV have been identified, to date, only one serotype of HEV has been recognized. Therefore, it may be possible to produce a broadly protective vaccine. Passively transferred anti-HEV serum significantly reduced virus shedding in feces and abrogated disease in nonhu...

Measurement of electrical impedance is a relatively new real-time and label-free method for monitoring cell adhesive properties. Impedance measurements are performed in tissue culture wells in which the bottom is equipped with gold electrodes. The extent of electrode coverage by living cells as well as the strength of the bond between the cell membrane and the electrode surface determines the impedance, which in real-time cell electrical sensing (RT-CES, ACEA Biosciences, San Diego, CA) is measured as the cell index (CI). We showed for carcinoma cells that CI was linearly correlated to the number of cells and that CI also was related to the amount of coating (laminin-5) of the wells. When natural killer (NK) cells were added to adherent carcinoma cells (target cells) CI declined rapidly dependent on the NK cell:target cell ratio. The initial decrease of CI was much more pronounced than target cell death as measured by [(3)H]thymidine incorporation assay. Such a rapid fall of CI was due to changes in the adhesion and morphology of target cell undergoing apoptosis. It took more than 6 h before the extent of cell death and fall of CI were comparable. We also showed using A431 cells and an antibody specific for the human epidermal growth factor receptor (Erbitux, manufactured by Merck KGaA, Darmstadt, Germany) that RT-CES could be used to monitor antibody-dependent cellular cytotoxicity. Thus RT-CES is a convenient way to continuously determine cell number and cell adhesion and may offer early detection of NK cell-mediated cytotoxic effects.

Several cDNA clones comprising the entire coding sequence of the rainbow trout (Oncorhynchus mykiss) major histocompatibility comlex (Mhc) class II B gene have been isolated from different sources. A single B gene appears to be transcribed in the rainbow trout and it encodes a 247 amino acid long polypeptide, which is of similar size to mammalian, avian, and amphibian and other teleost beta chains. The amino acid sequence identity to mammalian, amphibian, and avian class II beta chains is only about 30%. Despite the low similarity, a striking pattern of conservation is observed, both in the putative peptide-binding domain and in the Ig-like domain. Most of the conserved residues are located in the Ig-like domain and in the transmembrane segment. The majority of polymorphic residues reside in the beta 1 domain, with the greatest variability found in the amino-terminal half of the domain. The sequence data are compatible with a rather limited polymorphism of a single, expressed Mhc class II B gene.

ABSTRACT.A humoral immune response of European eel Anguilla anguilla to a major antigen in the swimbladder nematode Anguillicola crassus was demonstrated by irnmuno-blotting. Proteins from the nematode were separated using SDS-PAGE (sodium-dodecyl-sulfate polyacrylamide-gel electrophoresis) under reducing conditions and electroblotted onto nitrocellulose membranes, which were incubated in diluted serum from either infected or non-infected eels. Secondary and tertiary antibodies were rabbit anti-eel Ig serum and peroxidase-conjugated swine anti-rabbit Ig antibodies, respectively. Infected eels showed a specific antibody response towards a 43 kDa parasite antigen. The immunoblotting technique seems to provide a serodiagnostic research tool for detecting A. crassus infection in the European eel.