HUMORAL AND CELLULAR IMMUNE-RESPONSES OF DOGS IMMUNIZED WITH A NUCLEIC-ACID VACCINE ENCODING HUMAN CARCINOEMBRYONIC ANTIGEN

A nucleic acid vaccine encoding human carcinoembryonic antigen (CEA) w as administered to 10 juvenile dogs, 10-15 weeks of age, by four paren teral routes. The routes tested were intramuscular injection using a n eedle and syringe, intramuscular injection using the Biojector needlel ess injection device, intradermal injection or intravenous injection.. All groups received 150 mu g of plasmid DNA on weeks 0, 4, 7 and 13. All dogs were bled weekly for 17 weeks and rested for antibody against human CEA. Dogs given plasmid intramuscularly either by needle and sy ringe or Biojector showed significant antibody responses by week 9 whi ch peaked by week 15 Dogs receiving plasmid intravenously showed sligh t, unsustained increases in antibody titers while dogs receiving plasm id intradermally had significant titers, but at levels approximately o ne log less than those induced by intramuscular injection. The five do gs immunized by intramuscular delivery of plasmid DNA were examined fo r cellular immune responses to human CEA by lymphoblast transformation (LBT) assay. All five showed significant CEA-specific lymphoprolifera tion when compared with unvaccinated dogs. Physical examination, clini cal chemistry, hematology and histopathology examinations revealed no abnormalities associated with nucleic acid immunization.