• Vaccine Name: C. abortus DNA vaccine encoding DnaK
• Target Pathogen: Chlamydophila abortus
• Target Disease: Abortion and fetal death
• Vaccine Ontology ID: VO_0011518
• Type: DNA vaccine
• Status: Research
• Antigen: C. abortus molecular chaperone DnaK
• dnaK gene engineering:
  • Type: DNA vaccine construction
  • Description: The dnaK gene was amplified by the polymerase chain reaction (PCR) and cloned in the appropriate vectors. PCR was performed using chlamydial genomic DNA (80 ng) as the template. The resulting fragment was inserted into the pcDNA3.1 (Invitrogen) eukaryotic vaccinal vector carrying the human cytomegalovirus immediate early-promoter and the bovine growth hormone polyadenylation signal after linearization by BamHI-XbaI double digestion to generate pcDNA3.1::DnaK. pcDNA3.1::DnaK and pcDNA3.1 control plasmid were purified after an overnight Luria Bertani (LB) culture of recombinant DH5a E. coli using the EndoFree™ (Héchard et al., 2002).
  • Detailed Gene Information: Click Here.
• DNA vaccine plasmid:
  • DNA vaccine plasmid name:
  • DNA vaccine plasmid VO ID: VO_0000158
• Immunization Route: Intramuscular injection (i.m.)

Mouse Response

• Host Strain: OF1 Swiss
• Vaccination Protocol: Prior to DNA immunization, each mouse was injected with cardiotoxin (Latoxan, Rosans, France) into the tibialis anterior muscles of both ind legs. Cardiotoxin induces a local inflammation and enhances the uptake of plasmid DNA. Five days later, the mice were anesthetized by intraperitoneal injection of ketamine and xylazine (80 and 8 mg/kg of body weight, respectively) and immunized with pcDNA3.1 or pcDNA3.1::DnaK plasmids by intramuscular injections (50 mg in each tibialis anterior). The mice were boosted in the same way at days 21 and 42, mated at day 51 and challenged at day 63 by an intraperitoneal injection of 2 ´ 10^5 plaque forming units (pfu) of C. abortus AB7 (Héchard et al., 2002).
• Challenge Protocol: Four groups of 16 non-pregnant mice were made for immunological trials. Non-pregnant mice were used in order to collect samples without affecting the pregnancy of the mice. Moreover, a good vaccine must be able to protect pregnant and non-pregnant animals. As for the mice of the abortion test, these non-pregnant mice were immunized with the 1B vaccine, pcDNA3.1 or pcDNA3.1::DnaK.One additional group was immunized by PBS (same quantity, site and time as the DNA injections) and consequently was related as the virulence control group (Héchard et al., 2002).
• Efficacy: In pregnant mice, the dnaK vaccine induced a non-specific partial protection from abortion after challenge with Chlamydophila abortus (Héchard et al., 2002).
• Host Ighv1-9 response
  • Description: In non-pregnant mice, the dnaK vaccine induced a specific humoral response with the predominant serum IgG2a isotope. No antibody response was detected in non-immunized mice or with the control plasmid. Increases in serum IgG2a were seen at day 41, increasing until day 61 with a drop on day 68 to levels similar to those seen on day 41 (Héchard et al., 2002).
  • Detailed Gene Information: Click Here.