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Gutiérrez RL, Porter CK, Harro C, Talaat K, Riddle MS, DeNearing B, Brubaker J, Maciel M, Laird RM, Poole S, Chakraborty S, Maier N, Sack DA, Savarino SJ. Efficacy Evaluation of an Intradermally Delivered Enterotoxigenic Escherichia coli CF Antigen I Fimbrial Tip Adhesin Vaccine Coadministered with Heat-Labile Enterotoxin with LT(R192G) against Experimental Challenge with Enterotoxigenic E. coli H10407 in Healthy Adult Volunteers. Microorganisms 2024; 12:288. [PMID: 38399692 PMCID: PMC10892241 DOI: 10.3390/microorganisms12020288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 01/16/2024] [Accepted: 01/26/2024] [Indexed: 02/25/2024] Open
Abstract
BACKGROUND Enterotoxigenic E. coli (ETEC) is a principal cause of diarrhea in travelers, deployed military personnel, and children living in low to middle-income countries. ETEC expresses a variety of virulence factors including colonization factors (CF) that facilitate adherence to the intestinal mucosa. We assessed the protective efficacy of a tip-localized subunit of CF antigen I (CFA/I), CfaE, delivered intradermally with the mutant E. coli heat-labile enterotoxin, LTR192G, in a controlled human infection model (CHIM). METHODS Three cohorts of healthy adult subjects were enrolled and given three doses of 25 μg CfaE + 100 ng LTR192G vaccine intradermally at 3-week intervals. Approximately 28 days after the last vaccination, vaccinated and unvaccinated subjects were admitted as inpatients and challenged with approximately 2 × 107 cfu of CFA/I+ ETEC strain H10407 following an overnight fast. Subjects were assessed for moderate-to-severe diarrhea for 5 days post-challenge. RESULTS A total of 52 volunteers received all three vaccinations; 41 vaccinated and 43 unvaccinated subjects were challenged and assessed for moderate-to-severe diarrhea. Naïve attack rates varied from 45.5% to 64.7% across the cohorts yielding an overall efficacy estimate of 27.8% (95% confidence intervals: -7.5-51.6%). In addition to reducing moderate-severe diarrhea rates, the vaccine significantly reduced loose stool output and overall ETEC disease severity. CONCLUSIONS This is the first study to demonstrate protection against ETEC challenge after intradermal vaccination with an ETEC adhesin. Further examination of the challenge methodology is necessary to address the variability in naïve attack rate observed among the three cohorts in the present study.
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Affiliation(s)
- Ramiro L. Gutiérrez
- Naval Medical Research Command, Silver Spring, MD 20910, USA; (R.L.G.); (M.S.R.); (R.M.L.); (S.P.); (S.J.S.)
| | - Chad K. Porter
- Naval Medical Research Command, Silver Spring, MD 20910, USA; (R.L.G.); (M.S.R.); (R.M.L.); (S.P.); (S.J.S.)
| | - Clayton Harro
- Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21224, USA (K.T.); (B.D.); (D.A.S.)
| | - Kawsar Talaat
- Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21224, USA (K.T.); (B.D.); (D.A.S.)
| | - Mark S. Riddle
- Naval Medical Research Command, Silver Spring, MD 20910, USA; (R.L.G.); (M.S.R.); (R.M.L.); (S.P.); (S.J.S.)
| | - Barbara DeNearing
- Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21224, USA (K.T.); (B.D.); (D.A.S.)
| | - Jessica Brubaker
- Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21224, USA (K.T.); (B.D.); (D.A.S.)
| | - Milton Maciel
- Naval Medical Research Command, Silver Spring, MD 20910, USA; (R.L.G.); (M.S.R.); (R.M.L.); (S.P.); (S.J.S.)
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD 20817, USA
| | - Renee M. Laird
- Naval Medical Research Command, Silver Spring, MD 20910, USA; (R.L.G.); (M.S.R.); (R.M.L.); (S.P.); (S.J.S.)
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD 20817, USA
| | - Steven Poole
- Naval Medical Research Command, Silver Spring, MD 20910, USA; (R.L.G.); (M.S.R.); (R.M.L.); (S.P.); (S.J.S.)
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD 20817, USA
| | - Subra Chakraborty
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA;
| | | | - David A. Sack
- Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21224, USA (K.T.); (B.D.); (D.A.S.)
| | - Stephen J. Savarino
- Naval Medical Research Command, Silver Spring, MD 20910, USA; (R.L.G.); (M.S.R.); (R.M.L.); (S.P.); (S.J.S.)
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