In vitro and in vivo analyses of constitutive and in vivo-induced promoters in attenuated vaccine and vector strains of Vibrio cholerae

The optimal promoter for in vivo expression of heterologous antigens by live, attenuated vaccine vector strains of Vibrio cholerae is unclear; in vitro analyses of promoter activity may not accurately predict expression of antigens in vivo. We therefore introduced plasmids expressing the B subunit o...

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Bibliographic Details
Published in:Infection and immunity 2000-03, Vol.68 (3), p.1171-1175
Main Authors: JOHN, M, CREAN, T. I, CALDERWOOD, S. B, RYAN, E. T
Format: Article
Language:English
Subjects:
Animals
Antibodies, Bacterial - blood
Bacterial Vaccines - genetics
Bacteriology
Biological and medical sciences
Cholera Toxin - genetics
Cholera Toxin - immunology
DNA vaccines
Female
Fundamental and applied biological sciences. Psychology
Genetic Vectors
htpC gene
irgA gene
Mice
Microbial Immunity and Vaccines
Microbiology
Promoter Regions, Genetic
tac gene
Vaccines, antisera, therapeutical immunoglobulins and monoclonal antibodies
Vaccines, Inactivated - genetics
Vibrio cholerae
Vibrio cholerae - genetics
Vibrio cholerae - immunology
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Summary:The optimal promoter for in vivo expression of heterologous antigens by live, attenuated vaccine vector strains of Vibrio cholerae is unclear; in vitro analyses of promoter activity may not accurately predict expression of antigens in vivo. We therefore introduced plasmids expressing the B subunit of cholera toxin (CtxB) under the control of a number of promoters into V. cholerae vaccine strain Peru2. We evaluated the tac promoter, which is constitutively expressed in V. cholerae, as well as the in vivo-induced V. cholerae heat shock htpG promoter and the in vivo-induced V. cholerae iron-regulated irgA promoter. The functionality of all promoters was confirmed in vitro. In vitro antigenic expression was highest in vaccine strains expressing CtxB under the control of the tac promoter (2 to 5 microgram/ml/unit of optical density at 600 nm [OD(600)]) and, under low-iron conditions, in strains containing the irgA promoter (5 microgram/ml/OD(600)). We orally inoculated mice with the various vaccine strains and used anti-CtxB immune responses as a marker for in vivo expression of CtxB. The vaccine strain expressing CtxB under the control of the tac promoter elicited the most prominent specific anti-CtxB responses in vivo (serum immunoglobulin G [IgG], P
ISSN:0019-9567
1098-5522
DOI:10.1128/IAI.68.3.1171-1175.2000