Vaccination with plasmid DNA expressing antigen from genomic or cDNA gene forms induces equivalent humoral immune responses

The antibody response to DNA vaccines containing either cDNA or genomic gen e forms of the host protective antigen, 45W from Taenia ovis was compared i n vaccinated Balb/c mice and outbred sheep by enzyme linked immunosorbant a ssay (ELISA). Plasmid DNA vaccines containing cDNA or genomic forms of the Taenia ovis host protective antigen 45W were constructed. In vitro transfec tion of Cos7 cell monolayers with the DNA vaccines revealed expression of f ull length, highly glycosylated 45W antigen of 40-65 kDa molecular weight. Glycosylation was confirmed using tunicamycin, where tunicamycin-treated tr ansfected cells expressed a 45W protein of 28 kDa. Immunisation of Balb/c m ice by intramuscular injection or gene gun delivery of plasmid DNA generate d equivalent high titre antibody responses, regardless of whether the antig en gene contained introns. Intramuscular vaccination of outbred sheep with plasmid DNA also generated antibody responses, albeit of low titre. The fin e specificity of the antibody response induced by DNA vaccination was compa red with that elicited by immunisation with recombinant 45W protein. DNA va ccination elicited antibodies which did not bind linear peptide determinant s, in contrast to serum from protein vaccinated mice. This result suggests that DNA vaccination elicits predominantly conformation;specific antibodies . (C) 1999 Elsevier Science Ltd. All rights reserved.