The expression of CD8α discriminates distinct T cell subsets in teleost fish.

CD8, belonging to the TCR complex, is the main marker molecule of CTLs. Although CD8 genes have been detected in many fish species, the analysis of teleost CD8+ cells has been limited because of the lack of antibodies. Using newly established mAbs against rainbow trout CD8α, we found high ratios of CD8α+ cells in trout thymus, gill and intestine, but relatively low abundance in pronephros, spleen and blood.

Genetic characterization of Streptococcus phocae strains isolated from Atlantic salmon, Salmo salar L., in Chile.

Streptococcus phocae is a beta-haemolytic bacterium frequently involved in disease outbreaks in seals causing pneumonia or respiratory infection. Since 1999, this pathogen has been isolated from diseased Atlantic salmon, Salmo salar, causing serious economic losses in the salmon industry in Chile. In this study, we used different molecular typing methods, such as pulsed-field gel electrophoresis (PFGE), randomly amplified polymorphic DNA (RAPD), enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR), repetitive extragenic palindromic PCR (REP-PCR) and restriction of 16S-23S rDNA intergenic spacer regions to evaluate the genetic diversity in S.

Antigenic and molecular characterization of Vibrio ordalii strains isolated from Atlantic salmon Salmo salar in Chile.

Biochemical, serological and molecular properties of a group of 14 Vibrio ordalii strains isolated from cultured Atlantic salmon Salmo salar in Chile in recent years were studied. The characteristics of isolates were compared with the type strain V. ordalii ATCC 33509T.

Isolation, sequencing and phylogenetic analysis of the hemagglutinin, neuraminidase and nucleoprotein genes of the Chilean equine influenza virus subtypes H7N7 and H3N8.

We report here on the isolation and sequencing of the hemagglutinin, neuraminidase and nucleoprotein genes of the Chilean equine influenza virus subtypes H7N7 (A/equi-1/Santiago/77, Sa77) and H3N8 (A/equi-2/Santiago/85, Sa85). The sequences obtained allowed a variability analysis, which indicated significant differences when compared with other isolates. We found that Chilean isolates are more similar to the North American variety than to European isolates.

Development of monoclonal antibodies to gizzerosine, a toxic component present in fish meal.

This study is the first report of the development of monoclonal antibodies (MAbs) against gizzerosine (GZ), one of the causative agents of black vomit, a serious poultry disease. Balb/c mice were immunized with different GZ conjugates; the most immunogenic conjugate in experimental animals was determined by enzyme-linked immunoadsorbent assays (ELISA). Somatic fusions were carried out using splenic lymphocytes from GZ-immune mice and the NSO/2 myeloid cell line.

A motif within the T cell receptor alpha chain constant region connecting peptide domain controls antigen responsiveness.

Mutant alphabeta TCRs were generated by replacing domains of the alpha and beta chain constant regions with homologous domains from TCR delta and gamma chains, respectively. Chimeric TCRs in which the alpha chain contains TCR delta chain sequences within the connecting peptide domain are unresponsive to alloantigens and superantigens, and have defective interactions with the CD3/zeta complex. Although these antigen-unresponsive TCRs undergo zeta chain phosphorylation upon stimulation with superantigen, they do not generate a full signal capable of producing IL-2.

A murine macrophage line of the H-2d/f haplotype can activate H-2k suppressor T cells.

Little is known about the molecular basis for activation of suppressor T cells. In this report we describe two macrophage cell lines, BAC1.2.

Monoclonal anti-idiotypic antibodies to an I-J interacting molecule inhibit suppression in an H-2 restricted way.

We have obtained 10 mAb from two independent fusions that are anti-idiotypic to the combining site of an anti-I-Jk antibody. These mAb block Ts cell function isn a genetically restricted manner in vitro and in vivo and recognize a determinant on macrophage membranes. In addition, they do not affect the I-Ek-restricted activation of a Th cell line specific for pigeon heart cytochrome c.