title: Development of safe, effective and immunogenic vaccine candidate for diarrheagenic Escherichia coli main pathotypes in a mouse model.
abstract: BACKGROUND
  Enteric and diarrheal diseases are important causes of childhood death in the developing world. These diseases are responsible for more than 750 thousand deaths in children under 5 years old worldwide, ranking second cause of death, after lower respiratory diseases, in this age group. Among the major causative agents of diarrhea is Escherichia coli. There are several vaccine trials for diarrheagenic E. coli. However, diarrheagenic E. coli has seven pathotypes and vaccines are directed for one or two of the five main pathotypes-causing diarrhea. Currently, there are no combined vaccines available in the market for all five diarrheagenic E. coli pathotypes. Therefore, we aimed to develop a low-cost vaccine candidate combining the five main diarrheagenic E. coli to offer wide-spectrum protection. We formulated a formalin-killed whole-cell mixture of enteroaggregative, enteropathogenic, enteroinvasive, enterohemorrhagic, and enterotoxigenic E. coli pathotypes as a combined vaccine candidate.
  
  
  RESULTS
  We immunized Balb/C mice subcutaneously with 10(9) CFU of combined vaccine candidate and found a significant increase in survival rate post challenge compared to unimmunized controls (100 % survival). Next we aimed to determine the immunological response of mice to the combined vaccine candidate compared to each pathotype immunization. To do so, we immunized mice groups with combined vaccine candidate and monitored biomarkers levels over 6 weeks as well as measured responses post challenge with relevant living E. coli. We found significant increase in specific systemic antibodies (IgG), interferon gamma (IFNγ) and interleukin 6 (IL-6) levels elicited by combined vaccine candidate especially in the first 2 weeks after mice immunization compared to controls (p < 0.05). We also evaluated alum and cholera toxin B subunit (CTB) as potential adjuvant systems for our candidate vaccine. We found that CTB-adjuvanted combined vaccine candidate showed significantly higher IgG and IFNγ levels than alum.
  
  
  CONCLUSIONS
  Overall, our combined vaccine candidate offered protection against the five main diarrheagenic E. coli pathotypes in a single vaccine using mouse model. To the best of our knowledge, this is the first combined vaccine against the five main diarrheagenic E. coli pathotypes that is cost-effective with promise for further testing in humans.
authors: Viral Control Unit, National Organization of Research and Control of Biological, Cairo, Egypt. asma.gohar@yahoo.com.
authors: Asmaa
authors: A
authors: Gohar
authors: Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Kasr El-Aini, Cairo, 11562, Egypt. nourtan@gmail.com.
authors: Nourtan F
authors: NF
authors: Abdeltawab
authors: Viral Control Unit, National Organization of Research and Control of Biological, Cairo, Egypt. fahmy.aly@gmail.com.|Research and Development Sector, Egyptian Company for Production of Vaccines, Sera and Drugs, The Holding Company for Biological Products and Vaccines (VACSERA), Cairo, Egypt. fahmy.aly@gmail.com.
authors: Ali
authors: A
authors: Fahmy
authors: Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Kasr El-Aini, Cairo, 11562, Egypt. magdy_biotek3@yahoo.com.
authors: Magdy A
authors: MA
authors: Amin
mesh_terms: D000276:Adjuvants, Immunologic; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood / Q000276:immunology; D000917:Antibody Formation / Q000276:immunology; D002772:Cholera Toxin / Q000276:immunology; D004195:Disease Models, Animal; D055808:Drug Discovery; D054307:Enterotoxigenic Escherichia coli / Q000276:immunology*; D004926:Escherichia coli / Q000276:immunology*; D022361:Escherichia coli Vaccines / Q000276:immunology*; D007114:Immunization; D007074:Immunoglobulin G / Q000276:immunology; D018836:Inflammation Mediators / Q000097:blood; D007371:Interferon-gamma / Q000097:blood; D015850:Interleukin-6 / Q000097:blood; D008807:Mice, Inbred BALB C; D016019:Survival Analysis
chemical_list: D000276:Adjuvants, Immunologic; D000907:Antibodies, Bacterial; D022361:Escherichia coli Vaccines; D007074:Immunoglobulin G; D018836:Inflammation Mediators; D015850:Interleukin-6; D007371:Interferon-gamma; D002772:Cholera Toxin