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Memórias do Instituto Oswaldo Cruz
Fundação Oswaldo Cruz, Fiocruz
ISSN: 1678-8060 EISSN: 1678-8060
Vol. 112, No. 2, 2017, pp. 123-130
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Bioline Code: oc17016
Full paper language: English
Document type: Research Article
Document available free of charge
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Memórias do Instituto Oswaldo Cruz, Vol. 112, No. 2, 2017, pp. 123-130
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Stable expression of Mycobacterium bovis antigen 85B in auxotrophic M. bovis bacillus Calmette-Guérin
Rizzi, Caroline; Peiter, Ana Carolina; Oliveira, Thaís Larré; Seixas Neto, Amilton Clair Pinto; Leal, Karen Silva; Hartwig, Daiane Drawanz; Seixas, Fabiana Kommling; Borsuk, Sibele & Dellagostin, Odir Antônio
Abstract
BACKGROUND Bovine tuberculosis (TB) is a zoonotic disease caused by Mycobacterium bovis, responsible for causing major
losses in livestock. A cost effective alternative to control the disease could be herd vaccination. The bacillus Calmette-Guérin
(BCG) vaccine has a limited efficacy against bovine TB, but can improved by over-expression of protective antigens. The M.
bovis antigen 85B demonstrates ability to induce protective immune response against bovine TB in animal models. However,
current systems for the construction of recombinant BCG expressing multiple copies of the gene result in strains of low genetic
stability that rapidly lose the plasmid in vivo. Employing antibiotic resistance as selective markers, these systems also compromise
vaccine safety. We previously reported the construction of a stable BCG expression system using auxotrophic complementation
as a selectable marker.
OBJECTIVES The fundamental aim of this study was to construct strains of M. bovis BCG Pasteur and the auxotrophic M. bovis
BCG ΔleuD expressing Ag85B and determine their stability in vivo.
METHODS Employing the auxotrophic system, we constructed rBCG strains that expressed M. bovis Ag85B and compared their
stability with a conventional BCG strain in mice. Stability was measured in terms of bacterial growth on the selective medium
and retention of antigen expression.
FINDINGS The auxotrophic complementation system was highly stable after 18 weeks, even during in vivo growth, as the
selective pressure and expression of antigen were maintained comparing to the conventional vector.
MAIN CONCLUSION The Ag85B continuous expression within the host may generate a stronger and long-lasting immune
response compared to conventional systems.
Keywords
bovine tuberculosis; recombinant BCG; auxotrophic complementation; foreign antigens
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