A double-blind, placebo-controlled trial to evaluate the efficacy of PTL-003, an attenuated enterotoxigenic E. coli (ETEC) vaccine strain, in protecting against challenge with virulent ETEC.
Enterotoxigenic E. coli (ETEC) are an important cause of diarrhea in developing countries, especially among indigenous children and travelers. In this randomized, double-blind, placebo-controlled trial, a live, attenuated CS1/CS3 ETEC strain, PTL-003, was tested as a potential vaccine strain. Thirty-three subjects drank buffered solutions containing either PTL-003 or placebo on Days 0 and 10 and were challenged with virulent CS1/CS3 ETEC strain E24377A on Day 28. The vaccine did not protect against moderate to severe ETEC illness (the primary endpoint), but it did prime subjects for a rapid antibody response to CS1 and CS3 after challenge, suggesting that a dose of vaccine on Day 28 might improve the immune response to the vaccine. Higher serum anti-CS3 IgA titers at the time of challenge correlated with less severe diarrheal illness.
McKenzie
Robin
R
Division of Infectious Diseases, Johns Hopkins University, Johns Hopkins Bayview Medical Center, 4940 Eastern Avenue, Baltimore, MD 21224, United States. rmckenz@jhmi.edu
Darsley
Michael
M
Thomas
Nicola
N
Randall
Roger
R
Carpenter
Colleen
C
Forbes
Edrick
E
Finucane
Mariel
M
Sack
R Bradley
RB
Hall
Eric
E
Bourgeois
August L
AL
D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D000907:Antibodies, Bacterial / Q000097:blood; D003906:Developing Countries; D003967:Diarrhea / Q000517:prevention & control; D004311:Double-Blind Method; D054307:Enterotoxigenic Escherichia coli / Q000276:immunology*; D004927:Escherichia coli Infections / Q000517:prevention & control*; D022361:Escherichia coli Vaccines / Q000008:administration & dosage / Q000276:immunology*; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D008875:Middle Aged; D010919:Placebos / Q000008:administration & dosage; D012720:Severity of Illness Index; D013223:Statistics as Topic; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000276:immunology
D000907:Antibodies, Bacterial; D022361:Escherichia coli Vaccines; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D010919:Placebos; D014613:Vaccines, Attenuated