Nucleic acid immunisation with a reporter gene results in antibody production in goldfish (Carassius auratusL.)

Reporter genes are increasingly being used in order to assess new approaches to immunisation with nucleic acids. In the present work goldfish (Carassius auratusL.) received theEscherichia coliβ-galactosidase (β-gal) reporter gene under control of the immediate early promoter/enhancer of the human cytomegalovirus by intramuscular injection just anterior to the dorsal fin. β-gal activity was detected at the site of injection after 4 days. Antibody to β-gal was present in the sera of fish killed at 4 and 8 weeks after DNA injection. In parallel experiments with mice only half the mice were positive for antibody, this being mainly of the IgG2a isotype, at 4 weeks after injection of DNA into their anterior tibial muscles. This suggests goldfish can sero-convert more readily than mice within 4 weeks of DNA injection using the β-gal reporter gene.