Assessment of DNA vaccine potential for juvenile Japanese flounder Paralichthys olivaceus, through the introduction of reporter genes by particle bombardment and histopathology

Abstract

The potential for genetic immunization, following DNA particle bombardment for juvenile (4.7cm ±0.3) Japanese flounder Paralichthys olivaceus was examined. Histopathology, at 3 hours post bombardment showed considerable damage to fish epithelial and dermal tissues when bombarded at pressures greater than 200 psi, with many DNA-coated gold particles found to be present. Histopathology, examined at 1, 7, 14 and 28 days post-bombardment showed little pathology at 150 psi with few DNA-coated particles, whereas at 300 psi there was significant pathology observed with many DNA-coated particles seen in conjunction with the cytoplasm of inflammatory cells. Between days 14 and 28 post-bombardment complete epithelial coverage was observed with tissue damage restricted to the dermal layer. CAT assay, following administration of plasmid DNA constructs at 250 psi, showed long term and stable expression of the CAT protein from day 1 to day 60. The transcription activity of two promoters, pCMV-CAT and pSV2-CAT showed marginally greater activity in the former. We conclude that the potential for DNA vaccination of juvenile flounder to be a viable option.