Search

Lymphocyte cell kinase ( LCK) belongs to the Src family of tyrosine kinases, which involves in the proliferation control of lymphocytes. In this study, we cloned the LCK gene of humphead snapper ( Lutjanus sanguineus) (designed as Ls LCK). Sequence analysis showed that the full-length cDNA of Ls LCK was 2279 bp, contained a 1506-bp open reading frame ( ORF), encoding a polypeptide of 501 amino acids. The deduced amino acid possessed the typical structural features of known LCK proteins, including four Src homology ( SH) domains arranged as the SH1 domain followed by a regulatory C-terminal tail ( COOH-domain), SH2 and SH3 adapter domains and SH4 domain which required for membrane attachment and CD4/ CD8 binding. Fluorescent quantitative real-time PCR analysis indicated that Ls LCK transcripts were expressed mainly in thymus, spleen and head kidney in healthy fish. Moreover, the mRNA expressions in these tissues were significantly up-regulated after challenge with Vibrio harveyi. The results of immunohistochemistry showed that Ls LCK protein localized distinctly in cytoplasm of cell in thymus, spleen and head kidney. Taken together, these findings indicated that Ls LCK may play an important role in the immune response of humphead snapper against bacterial infection. [ABSTRACT FROM AUTHOR]

The outer membrane proteins of the marine aquatic animal pathogen, Vibrio alginolyticus, play an important role in the virulence of the bacterium and are potential candidates for vaccine development. In this study, the gene encoding an outer membrane protein- Omp U was cloned and expressed in Escherichia coli. Polyclonal antibodies were raised in rabbits against the purified recombinant Omp U, and the reaction of the antibody was confirmed by Western blotting using the isolated Omp U and the recombinant Omp U of V. alginolyticus. To analyze the immunogenicity of the recombinant Omp U, crimson snapper, Lutjanus erythropterus Bloch, were immunized by intraperitoneal injection, and antibody response was assessed by the enzyme-linked immunosorbent assay ( ELISA). The results demonstrated that the recombinant Omp U produced an observable antibody response in all sera of the vaccinated fish. The vaccinated fish were challenged by virulent V. alginolyticus and observed to have high resistance to infection. These results indicate that the recombinant Omp U is an effective vaccine candidate against V. alginolyticus in L. erythropterus. [ABSTRACT FROM AUTHOR]

The purpose of this study was to develop a loop-mediated isothermal amplification (LAMP) method for rapid, sensitive, and simple detection of Streptococcus agalactiae in farmed fish. A set of four primers, two outer and two inner, was designed from the fibrinogen-binding (fbsB) proteins gene sequence of S. agalactiae, and conditions for LAMP were optimized as incubation of all reagents for 60 min at 64°C. LAMP products were judged by agar gel electrophoresis as well as the naked eye after development by Synergy Brands Green I (SYBR Green I). Sensitivity of the assay was 2.8 x 103 CFU/ml (2.8 CFU per reaction) and no positive amplification was detected for other related bacteria. This LAMP method can be used to detect S. agalactiae infection in the laboratory and the field. [ABSTRACT FROM AUTHOR]