Narrow Results

The aim of this study was to clone and express the ORF72 and ORF92 genes of koi herpesvirus (KHV) in a prokaryotic system and to examine the antigenicity of recombinant proteins. Phylogenetic analysis revealed that both ORF72 and ORF92 had 100% homology with KHV-J, and 99% homology with those from KHV-U and KHV-I in nucleotides. This suggests that the KHV isolate in Taiwan is more closely related to the Japanese strain (Asian genotype). In the antigenicity analysis, the crude recombinant ORF72 and ORF92 capsid proteins reacted with the positive sera of the survival fish after a KHV outbreak, indicating that these recombinant capsid proteins might mimic antigens of the wild type KHV to induce an immunological response in the infected host. Our results demonstrated potential for general applicability to serological tests and vaccine development.

Cholera toxin B subunit (CTB) mature protein was stably expressed in transgenic tobacco plants under the control of CaMV 35S promoter and TMV Ω fragment. Fusion of the PR1b signal peptide coding sequence to the CTB mature protein gene increased the expression level by 24-fold. The tobacco-synthesized CTB (tCTB) was purified to homogeneity by a single step of immunoaffinity chromatography. The purified tCTB is predominantly in the form of pentamers with molecular weight identical to the native pentameric CTB, indicating the PR1b-CTB fusion protein has been properly processed in tobacco cells. Futhermore, we have shown that the antigenicity of the purified tCTB is indistinguishable from that of the native CTB protein by immunodiffusion and immunoelectrophoresis.