Diarrhea is the second leading cause of death in children <5 years, and remains a major public health problem. Enterotoxigenic Escherichia coli (ETEC), the most common bacterial cause of diarrhea, causes 280 to 400 million diarrheal cases in children <5 years and 100 million more cases in children >5 years annually, resulting in 150,000 to 300,000 deaths annually. ETEC also commonly cause travellers? diarrhea. While improved sanitation is the eventual solution, vaccination will be the best preventive measure for many decades. Key virulence factors of ETEC are bacterial adhesins and enterotoxins. Adhesins mediate bacterial attachment to host receptors and colonization in small intestines. Enterotoxins, heat-labile toxin (LT) and heat- stable toxin (STa), disrupt intestinal fluid homeostasis to cause fluid hyper-secretion and diarrhea. A vaccine preventing bacteria colonization and neutralizing toxin enterotoxicity could effectively prevent ETEC diarrhea, but until now, a safe and effective ETEC vaccine has not been developed. Developing ETEC vaccines is challenging since the heterogeneous ETEC strains express at least 23 adhesins and 2 distinct toxins. As ETEC strains producing any one or two adhesins and either toxin (LT or STa) cause diarrhea, ideally, an effective ETEC vaccine should protect against all adhesins and both toxins. But protecting against 23 adhesins is not feasible and protecting against 2 toxins is very difficult. Additionally, suitable animal models to unambiguously assess efficacy of ETEC vaccine candidates have been lacking. In this study, we will develop a safe and broadly protective ETEC vaccine. We will apply a multiepitope fusion antigen (MEFA) method to create an adhesin MEFA to induce antibodies against the 7 key adhesins associates with 80% of ETEC diarrhea cases (caused by ETEC strains with known adhesins), and fuse an LT toxoid and a STa toxoid for a safe toxoid fusion to induce antibodies neutralizing both toxins. The adhesin MEFA and the toxoid fusion will be combined (co-administration) or further fused together (as a CFA-toxoid MEFA) to induce broadly protective anti-adhesin and antitoxin antibodies. We will then use a novel piglet and rabbit dual-challenge model to assess efficacy of a subunit vaccine candidate against ETEC diarrhea. Our preliminary studies show LT-STa toxoid fusions, adhesin MEFA and adhesin-toxoid fusion induce antibodies neutralizing both toxins and 7 adhesins and protecting pigs against ETEC diarrhea, and rabbits and pigs are ideal animal models for ETEC vaccine efficacy assessment. A broadly protective subunit ETEC vaccine will benefit millions of children and travelers. The innovative approaches developed in this research can be generally applied to multivalent vaccine development against other diseases.

Public Health Relevance

Projective Narrative: This collaborative project between Kansas State University and Johns Hopkins University will develop a safe and broadly protective subunit vaccine against enterotoxigenic E. coli (ETEC), the most common bacterial cause of diarrhea to children in developing countries (children?s diarrhea) as well as international travelers (travelers? diarrhea). ETEC diarrhea leads to the deaths of 150,000 to 300,000 children annually. Currently, there are no vaccines against ETEC associated diarrhea, but new innovative methods now make the development of a broadly protective subunit vaccine feasible. A successful vaccine will bring enormous benefits for global health, especially for children in developing countries and for international travelers.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI121067-03
Application #
9463753
Study Section
Vaccines Against Microbial Diseases Study Section (VMD)
Program Officer
Baqar, Shahida
Project Start
2016-05-26
Project End
2021-04-30
Budget Start
2018-05-01
Budget End
2019-04-30
Support Year
3
Fiscal Year
2018
Total Cost
Indirect Cost
Name
Kansas State University
Department
Veterinary Sciences
Type
Schools of Veterinary Medicine
DUNS #
929773554
City
Manhattan
State
KS
Country
United States
Zip Code
66506
Duan, Qiangde; Lu, Ti; Garcia, Carolina et al. (2018) Co-administered Tag-Less Toxoid Fusion 3xSTaN12S-mnLTR192G/L211A and CFA/I/II/IV MEFA (Multiepitope Fusion Antigen) Induce Neutralizing Antibodies to 7 Adhesins (CFA/I, CS1-CS6) and Both Enterotoxins (LT, STa) of Enterotoxigenic Escherichia coli (ETEC). Front Microbiol 9:1198
Duan, Qiangde; Huang, Jiachen; Xiao, Nan et al. (2018) Neutralizing Anti-Heat-Stable Toxin (STa) Antibodies Derived from Enterotoxigenic Escherichia coli Toxoid Fusions with STa Proteins Containing N12S, L9A/N12S, or N12S/A14T Mutations Show Little Cross-Reactivity with Guanylin or Uroguanylin. Appl Environ Microbiol 84:
Nandre, Rahul; Ruan, Xiaosai; Lu, Ti et al. (2018) Enterotoxigenic Escherichia coli Adhesin-Toxoid Multiepitope Fusion Antigen CFA/I/II/IV-3xSTaN12S-mnLTG192G/L211A-Derived Antibodies Inhibit Adherence of Seven Adhesins, Neutralize Enterotoxicity of LT and STa Toxins, and Protect Piglets against Diarrhea. Infect Immun 86:
Nandre, Rahul M; Duan, Qiangde; Wang, Yin et al. (2017) Passive antibodies derived from intramuscularly immunized toxoid fusion 3xSTaN12S-dmLT protect against STa+ enterotoxigenic Escherichia coli (ETEC) diarrhea in a pig model. Vaccine 35:552-556
Duan, Qiangde; Lee, Kuo Hao; Nandre, Rahul M et al. (2017) MEFA (multiepitope fusion antigen)-Novel Technology for Structural Vaccinology, Proof from Computational and Empirical Immunogenicity Characterization of an Enterotoxigenic Escherichia coli (ETEC) Adhesin MEFA. J Vaccines Vaccin 8:
Nandre, Rahul M; Ruan, Xiaosai; Duan, Qiangde et al. (2016) Antibodies derived from an enterotoxigenic Escherichia coli (ETEC) adhesin tip MEFA (multiepitope fusion antigen) against adherence of nine ETEC adhesins: CFA/I, CS1, CS2, CS3, CS4, CS5, CS6, CS21 and EtpA. Vaccine 34:3620-5