Avicenna J Med Biotech arij002 Avicenna Journal of Medical Biotechnology 2008-2835 2008-4625 Avicenna Research Institute ajmb30432 Immunogenic Potency of Formalin and Heat Inactivated E. coli O157:H7 in Mouse Model Administered by Different Routes ArshadiNasimMousavi Seyed LatifAmani JafarNazarianShahram 12 3 194 200 3 7 2019 1 2 2020

<p>Background: Enterohemorrhagic<em> Escherichia coli (E. coli)</em> (EHEC) O157:H7 is a major foodborne pathogen causing severe disease in humans worldwide. Cattle are important reservoirs of <em>E. coli</em> O157:H7 and developing a specific immunity in animals would be invaluable. The administration of Whole Cell Vaccines (WCV) is a well-established method of vaccination against bacterial infections. Route of administration, inactivation and using suitable adjuvant have significant effects on the characteristics and efficacy of WCV.</p> <p>Methods: In the present study, an attempt was made to evaluate the immunogenic potency of heat and formalin inactivated cells administered orally and subcutaneously in mouse model by ELISA. Mice pretreated with streptomycin were used as a model to evaluate the efficacy of subcutaneous versus oral administration of the vaccine. Following immunization, mice were infected with <em>E. coli</em> O157:H7 and feces were monitored for shedding.</p> <p>Results: Both forms of inactivated cells induced immune response and hence protection against infectious diseases caused by <em>E. coli</em> O157:H7. However, formalin inactivated cells of <em>E. coli</em> O157:H7 showed superior antigenicity compared to heat inactivated cells. Subcutaneous immunization of mice with both heat and formalin inactivated <em>E. coli</em> O157:H7 induced significant specific levels of IgG antibodies but did not lead to significant antigen-specific IgA rise in feces, whereas oral immunization elicited significant levels of IgG antibodies with some animals developing antigen-specific IgA in feces.</p> <p>Conclusion: Inactivated <em>E. coli</em> O157:H7 is highly immunogenic and can induce protective immune responses via oral immunization.</p>