Luciferase expression 2 years after DNA injection in glass catfish (Kryptopterus bicirrhus).

Glass catfish (Kryptopterus bicirrhus) have transparent muscles and skin. Intramuscular injection of DNA encoding luciferase into these fish induced luciferase expression that was measurable in vivo with a low light video image analyser. Expression could be detected up to at least 2 years after DNA injection. Although luciferase is not representative of all types of antigen, this study stresses the need for future studies directed to limit the period of antigen expression after DNA vaccination.