Recombinant cholera toxin B subunit and gene fusion proteins for oral vaccination.

Abstract

The B subunit portion of cholera toxin (CTB) is a safe and effective oral immunizing agent in humans, affording protection against both cholera and diarrhoea caused by enterotoxigenic Escherichia coli producing heat-labile toxin (LT) (Clemens et al., 1986; 1988). CTB may also be used as a carrier of various "foreign" antigens suitable for oral administration. To facilitate large-scale production of CTB for vaccine development purposes, we have constructed recombinant overexpression systems for CTB proteins in which the CTB gene is under the control of strong foreign (non-cholera) promoters and in which it is also possible to fuse oligonucleotides to the CTB gene and thereby achieve overexpression of hybrid proteins (Sanchez and Holmgren, 1989; Sanchez et al., 1988). We here expand these findings by describing overexpression of CTB by a constitutive tacP promoter as well as by the T7 RNA-polymerase promoter, and also by describing gene fusions leading to overexpression of several hybrid proteins between heat-stable E. coli enterotoxin (STa)-related peptides to either the amino or carboxy ends of CTB. Each of the hybrid proteins, when tested as immunogens in rabbits, stimulated significant anti-STa as well as anti-CTB antibody formation, although the anti-STa antibody levels attained (c.a. 1-15 micrograms/ml specific anti-STa immunoglobulin) were too low to give more than partial neutralization of STa intestinal challenge in baby mice. The hybrid proteins also had a near-native conformation, as apparent from their oligomeric nature and their strong reactivity with both a neutralizing antibody against the B subunit and a neutralizing monoclonal antibody (mAb) against STa.(ABSTRACT TRUNCATED AT 250 WORDS)

• Authors: J Sanchez, S Johansson, B Löwenadler, A M Svennerholm, J Holmgren
• Journal: Research in microbiology (Res Microbiol) 1990 Sep-Oct Vol. 141 Issue 7-8 Pg. 971-9 ISSN: 0923-2508 [Print] France
• PMID: 2101488 (Publication Type: Journal Article)

Chemical References

• Antibodies, Bacterial
• Cholera Vaccines
• Recombinant Fusion Proteins
• Vaccines, Synthetic
• Cholera Toxin

Topics

• Administration, Oral
• Amino Acid Sequence
• Animals
• Antibodies, Bacterial (biosynthesis)
• Cholera Toxin (genetics, immunology)
• Cholera Vaccines (administration & dosage, genetics, isolation & purification)
• Molecular Sequence Data
• Rabbits
• Recombinant Fusion Proteins (genetics, immunology)
• Vaccines, Synthetic (administration & dosage, genetics, isolation & purification)