Production of rabbit polyclonal antibody against apobec-1 by genetic immunization

Circulating apolipoprotein B (apoB) exists in two forms; apoB-100 and apoB-48. ApoB-48 is a truncated form of apoB resulting from RNA editing. The editing enzyme, called apobec-1, converts a cytidine (C) at nucleotide 6666 in apoB 100 mRNA to a uridine (U) and changes a CAA codon to an in-frame stop codon, UAA. We have produced a specific rabbit polyclonal antiserum against apobec-1 by genetic immunization. The cDNA of mouse apobec-1 was inserted downstream and in-frame at the BamH I site in the last exon of human growth hormone cDNA driven by a cytomegalovirus promoter. This plasmid was injected together with another plasmid expressing granulocyte macrophage colony-stimulating factor into the thigh muscles of a rabbit. The resulting antiserum demonstrated high specificity on Western blots, and inhibited the apoB mRNA editing activity of mouse liver extract in a dose-dependent manner. This report demonstrates that DNA immunization is a powerful technique that can be readily applied to other sparse or difficult-to-purify proteins in lipid metabolism.