Optimization of green fluorescent protein expression vectors for in vitro and in vivo detection of Listeria monocytogenes.
The green fluorescent protein (GFP) of the jellyfish Aequorea victoria is a useful reporter molecule for monitoring in vivo gene expression in eukaryotic and prokaryotic cells. We constructed a series of GFP vectors for in situ detection of the intracellular pathogen Listeria monocytogenes. The gfp-mutl gene, which encodes a red-shifted GFP, was transcriptionally fused to a strong L. monocytogenes promoter and inserted into various Escherichia coli-Listeria shuttle vectors: i) the integrative monocopy plasmid pAT113; ii) the low copy number plasmid pTCV-Exl; iii) the high copy number plasmid pAT18. Listeria cells harboring pNF6 and pNF7, constructed from pAT113 and pTCV-Exl, respectively, gave low fluorescence intensities, and were optically detected in cultured macrophages, but not in tissue sections. The fluorescence of Listeria with the pAT18 derivative pNF8 was about 40 times greater than that with pNF6 and 15 times greater than that with pNF7. Listeria cells harboring pNF8 were readily detected in both cultured macrophages and tissue sections. Constructed GFP vectors did not affect the virulence of L. monocytogenes in a murine model of infection.
Laboratoire de microbiologie, Institut national de la santé et de la recherche médicale U 411, Faculté de médecine Necker-Enfants Malades, Paris, France. fortineau@necker.fr
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N
Fortinea
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P
Trieu-Cuot
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O
Gaillot
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Pellegrini
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Berche
J L
JL
Gaillard
D000818:Animals; D015153:Blotting, Western; D003227:Conjugation, Genetic; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins; D008089:Listeria monocytogenes / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism / Q000472:pathogenicity; D008088:Listeriosis / Q000382:microbiology / Q000503:physiopathology; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism*; D008264:Macrophages / Q000382:microbiology; D051379:Mice; D008856:Microscopy, Fluorescence; D010957:Plasmids / Q000235:genetics; D014774:Virulence
D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins