Construction and preclinical evaluation of recombinant Peru-15 expressing high levels of the cholera toxin B subunit as a vaccine against enterotoxigenic Escherichia coli.
Enterotoxigenic Escherichia coli (ETEC) is the leading cause of traveler's diarrhea. The heat-labile (LT) and heat-stable (ST) toxins mediate ETEC induced diarrhea. ETEC strains may express LT, ST, or both LT and ST, with LT-expressing strains accounting for approximately 50-60% of ETEC-related traveler's diarrhea. Cholera toxin (CT) is >80% homologous to LT and vaccination with CT-B subunit (CT-B) -based vaccines elicit a protective immune response against LT-producing ETEC strains. Peru-15 is an oral, single-dose, live-attenuated cholera vaccine candidate that has been investigated in several clinical trials (n>400 subjects) and was proven well tolerated, immunogenic, and efficacious. Peru-15 was genetically engineered to express and secrete high levels of CT-B by cloning ctxB onto a glnA balanced-lethal plasmid under the transcriptional control of a strong constitutive promoter, resulting in Peru-15pCTB. In vitro characterization demonstrated that Peru-15pCTB secreted approximately 30-fold more CT-B than Peru-15 and CT-B was stably produced after 40 generations of growth and throughout simulated Seed Bank and FDP (Final Drug Product) production conditions. In preclinical studies, the geometric mean anti-CT-B IgG titer in the sera of mice inoculated intranasally with two doses of Peru-15pCTB was >32-fold higher than in mice inoculated with Peru-15. Similarly, rabbits orally inoculated with a single dose of Peru-15pCTB developed titers that were approximately 30-fold higher than rabbits inoculated with a single dose of Peru-15. Sera from Peru-15pCTB vaccinated mice and rabbits neutralized LT toxicity in an in vitro assay. Peru-15pCTB has several promising characteristics of an oral, single-dose, bivalent cholera/ETEC vaccine and is advancing towards a Phase 1 clinical trial.
Roland
Kenneth L
KL
AVANT Immunotherapeutics, Inc. 119 Fourth Avenue, Needham, MA 02494, United States.
Cloninger
Cheryl
C
Kochi
Sims K
SK
Thomas
Lawrence J
LJ
Tinge
Steven A
SA
Rouskey
Craig
C
Killeen
Kevin P
KP
D000276:Adjuvants, Immunologic / Q000235:genetics*; D000281:Administration, Intranasal; D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis / Q000096:biosynthesis; D000918:Antibody Specificity; D015153:Blotting, Western; D002772:Cholera Toxin / Q000235:genetics* / Q000276:immunology*; D022121:Cholera Vaccines / Q000008:administration & dosage / Q000235:genetics* / Q000276:immunology*; D003470:Culture Media; D004591:Electrophoresis, Polyacrylamide Gel; D054307:Enterotoxigenic Escherichia coli / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D004927:Escherichia coli Infections / Q000276:immunology*; D007074:Immunoglobulin G / Q000032:analysis / Q000096:biosynthesis / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D009500:Neutralization Tests; D010957:Plasmids / Q000235:genetics; D011817:Rabbits; D014614:Vaccines, Synthetic / Q000235:genetics / Q000276:immunology; D014734:Vibrio cholerae / Q000276:immunology
D000276:Adjuvants, Immunologic; D000907:Antibodies, Bacterial; D022121:Cholera Vaccines; D003470:Culture Media; D007074:Immunoglobulin G; D014614:Vaccines, Synthetic; D002772:Cholera Toxin