Recombinant channel catfish virus (Ictalurid herpesvirus 1) can express foreign genes and induce antibody production against the gene product

Abstract

The potential use of channel catfish virus (CCV) [fctalurid herpesvirus 1) as a vaccine vector for the channel catfish industry was investigated by inserting the Escherichia coli lacZ gene into the CCV genome and evaluating the immune response to the foreign gene product in catfish exposed to the recombinant. The recombinant virus was produced by inserting the lacX in reading frame with the ATG start codon of the CCV thymidine kinase (TK) gene in the recotnbinanr transfer plasmid pBSCV437 described previously. The plasmid was then cotransfccted with CCV DNA in aTK gene-mediated selectable homologous recombination. The recombinant progeny were selected by resistance to 0-1 mM acycloguanosinc (acyclovir) and the production of blue plaques in the presence of 5-bromo-4-chloro-3-indolyl-^-Dgalactopyranoside (X-gal). The resultant construct (CCVlacZ) was TK^, and contained the lacZ gene at both TK loci in the genome. jS-Galactosidase expression in infected CCO cells reached 0-33 /ig per 10'' CCO cells at 12 h post-infection. When channel catfish fingerlings were immersion exposed to CCVlacZ, these developed an antibody response to the inserted foreign gene product which peaked at approximately 13-20 days post-infection. Additionally, the anti-^galactosidase response was significantly enhanced when the fmgerlings were re-exposed to the virus 20 days after the initial exposure. These results demonstrate that foreign genes can be inserted into and expressed by CCV and that such constructs could be used as vaccine vectors.

Production and shedding of channel catfish virus (CCV) and thymidine kinase negative CCV in immersion exposed channel catfish fingerlings

“…A more complete understanding of the pathogenesis of these viruses requires sequential histopathological studies on the tissues to precisely locate cells and tissues involved in the viral entry, dissemination and shedding. Also the demonstrated reduction in persistence and shedding ability of CCVTK-is encouraging for recombinant CCVD vaccine and vaccine vector development (Zhang & Hanson 1996), as containment of recombinant viruses may not pose a serious problem. The presence of wild type CCV in CCVTK-challenged fish late in the preliminary experiment, as indicated by TCA precipitation assays, where the controls showed no sign of productlve infection implies a recrudescence of latent CCV and not tank to tank contamination.…”

Cyprinid viral diseases and vaccine development

“…The initial report of living-vehicle vaccine in aquatic organism was in 1995, preventing Salmonella in salmon [180]. Subsequently, the application of livingvehicle vaccine was reported to prevent Streptococcus [181], Edwardsiella tarda, A. hydrophila [182] and CCV [183].…”

Susceptibility of channel catfish fry to Channel Catfish Virus (CCV) challenge increases with age

“…Resale or republication not permitted without written consent of the publisher (CCVlacZ) was constructed that induces a humoral immune response to the foreign gene product in immersion exposed channel catfish fingerlings (Zhang & Hanson 1996). Therefore, this virus has great potential for use as a vaccine vector.…”