A DNA prime-Mycobacterium bovis BCG boost vaccination strategy for cattle induces protection against bovine tuberculosis.
The variable efficacy of bacillus Calmette-Guérin (Mycobacterium bovis BCG) in protecting humans and cattle against tuberculosis has prompted a search for a more effective vaccination regimen. A prime-boost strategy was investigated in cattle naturally sensitized to environmental mycobacteria by using a combination of three DNA vaccines coding for Hsp 65, Hsp 70, and Apa for priming, followed by a boost with BCG prior to experimental challenge with virulent M. bovis. Controls were vaccinated with DNA or BCG alone or were not vaccinated. The immune responses were monitored throughout the study, and protection was assessed based on reductions in the numbers of lesions and viable mycobacteria in lymph node samples. Vaccination with BCG alone or with a DNA prime-BCG boost regimen induced high levels of antigen-specific gamma interferon (IFN-gamma) in whole-blood cultures. In the prime-boost group there were fewer animals with severe lung lesions, fewer lymph nodes with lesions per animal, a smaller proportion of animals with lesions, lower mean lung and lymph node lesion scores, and less M. bovis isolated from retropharyngeal and thoracic lymph nodes compared to the results obtained for the nonvaccinated animals. The prime-boost regimen induced significant enhancement of protection in six parameters, compared with significant enhancement of protection in only two parameters for BCG alone. In addition, following challenge, in vitro IFN-gamma responses against ESAT-6 and CFP-10, as well as bovine tuberculin-induced skin test and in vitro IFN-gamma responses, were identified as immunological markers that predicted protection. The use of the prime-boost strategy suggested that a combination of vaccines may be better than a single vaccine for protection against tuberculosis.
Skinner
Margot A
MA
AgResearch, Wallaceville Animal Research Centre, Upper Hutt, New Zealand. margot.skinner@agresearch.co.nz
Buddle
Bryce M
BM
Wedlock
D Neil
DN
Keen
Denise
D
de Lisle
Geoffrey W
GW
Tascon
Ricardo E
RE
Ferraz
Jose Candido
JC
Lowrie
Douglas B
DB
Cockle
Paul J
PJ
Vordermeier
H Martin
HM
Hewinson
R Glyn
RG
D000818:Animals; D001500:BCG Vaccine / Q000008:administration & dosage* / Q000235:genetics; D001483:Base Sequence; D001717:Birds; D002417:Cattle; D015169:Colony Count, Microbial; D017931:DNA Primers / Q000235:genetics; D005260:Female; D006801:Humans; D007117:Immunization, Secondary; D066298:In Vitro Techniques; D007371:Interferon-gamma / Q000096:biosynthesis; D007376:Interleukin-2 / Q000096:biosynthesis; D009163:Mycobacterium bovis / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D013601:T-Lymphocytes / Q000276:immunology; D014373:Tuberculin / Q000494:pharmacology; D014380:Tuberculosis, Bovine / Q000276:immunology / Q000382:microbiology / Q000473:pathology / Q000517:prevention & control*; D019444:Vaccines, DNA / Q000008:administration & dosage* / Q000235:genetics
D001500:BCG Vaccine; D017931:DNA Primers; D007376:Interleukin-2; D014373:Tuberculin; D019444:Vaccines, DNA; D007371:Interferon-gamma