Evaluation of the persistence and gene expression of an anti-Chlamydophila psittaci DNA vaccine in turkey muscle.
BACKGROUND
DNA vaccination has been shown to elicit specific cellular and humoral immune responses to many different agents in a broad variety of species. However, looking at a commercial use, the duration of the immune response against the vaccine is critical. Therefore the persistence of the DNA vaccine, as well as its expression, should be investigated. We conducted these investigations on a DNA vaccine against Chlamydophila psittaci, a Gram-negative intracellular bacterium which causes respiratory disease in turkeys and humans. Previous studies showed that the DNA vaccine confers partial protection against C. psittaci infection in turkeys. Turkeys were injected intramuscularly with the DNA vaccine : a eukaryotic expression vector (pcDNA1::MOMP) expressing the major outer membrane protein (MOMP) of an avian C. psittaci serovar D strain. Over a period of 11 weeks, cellular uptake of the DNA vaccine was examined by PCR, transcription of the insert by reverse transcript-PCR (RT-PCR) and mRNA translation by immunofluorescence staining of muscle biopsies.


RESULTS
The results indicate that the DNA vaccine persists in turkey muscle for at least 10 weeks. Moreover, during this period of time MOMP was continuously expressed, as evidenced by the immunofluorescence staining and RT-PCR.


CONCLUSIONS
Since C. psittaci infections occur at the age of 3 to 6 and 8 to 12 weeks, a vaccine persistence of 10 weeks seems adequate. Therefore, further research should concentrate on improving the elicited immune response, more specifically the cell-mediated immune response, rather than prolonging the lifespan of the plasmid.
Loots
Karolien
K
Division of Gene Technology, Department of Biosystems, Faculty of Bioscience Engineering, Catholic University Leuven, Kasteelpark Arenberg 30, 3001 Leuven, Belgium. karolien.loots@biw.kuleuven.be
Vleugels
Bart
B
Ons
Ellen
E
Vanrompay
Daisy
D
Goddeeris
Bruno Maria
BM
D000818:Animals; D001428:Bacterial Vaccines / Q000008:administration & dosage / Q000032:analysis* / Q000235:genetics* / Q000276:immunology; D002691:Chlamydophila psittaci / Q000276:immunology*; D018482:Muscle, Skeletal / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011201:Poultry Diseases / Q000517:prevention & control; D009956:Psittacosis / Q000517:prevention & control / Q000662:veterinary; D012680:Sensitivity and Specificity; D014422:Turkeys / Q000276:immunology*; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000032:analysis* / Q000235:genetics* / Q000276:immunology
D001428:Bacterial Vaccines; D019444:Vaccines, DNA