Design, development, and evaluation of the efficacy of a nucleic acid-free version of a bacterial ghost candidate vaccine against avian pathogenic E. coli (APEC) O78:K80 serotype

Safoura Soleymani,Gholam Ali Kalidari,Hesam Dehghani,Amin Tavassoli,Gholamreza Hashemi Tabar

doi:10.1186/s13567-020-00867-w

Safoura Soleymani, Gholam Ali Kalidari + Show 3 more

Open Access

https://doi.org/10.1186/s13567-020-00867-w

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Journal: Veterinary Research	Publication Date: Dec 1, 2020
Citations: 14	License type: open-access

Affiliation: Ferdowsi University of Mashhad

Abstract

One of the major bacterial infectious diseases in the poultry industry is avian pathogenic Escherichia coli (APEC), which causes colibacillosis in chickens. To develop a novel nucleic acid-free bacterial ghost (BG) vaccine against the O78:K80 serotype of APEC, in this study we constructed a plasmid that harbored E-lysis and S nuclease (SNUC). Following the expression, the O78:K80 bacteria lost all of their cytoplasmic content and nucleic acids by enzymatic digestion. The functionality of these two proteins in the production procedure of bacterial ghosts was confirmed by monitoring the number of colonies, scanning electron microscopy imaging, gel electrophoresis of genomic DNA, and qPCR on the plasmid content of bacterial ghosts. The protective efficacy of the ghost vaccine generated from O78:K80 serotype of APEC was tested in chickens by injection and inhalation routes and compared with that in chickens that received the injection of a killed vaccine. The O78:K80 BG vaccine candidate, used as injection and inhalation, in comparison with the killed vaccine, triggered higher proinflammatory cytokine expression including IL-6, IL-1β, and TNFSF15; a higher level of antibody-dependent humoral (IgY and IgA) and cellular immune responses (IFNγ and lymphocyte proliferation); and lower lesion scores. According to the results of this study, we suggest that the bacterial ghost technology has the potential to be applied for the development of novel vaccines against avian colibacillosis. This technology provides an effective and reliable approach to make multivalent vaccines for more prevalent APEC strains involved in the establishment of this infectious disease in the poultry industry.

Highlights

Avian colibacillosis is one of the most commonly occurring bacterial diseases caused by avian pathogenic Escherichia coli (APEC) [1]
We demonstrate that the non-living O78:K80 bacterial ghost (BG) are effective as the killed bacteria in eliciting significant protection
Generation of nucleic acid‐free bacterial ghost against O78:K80 Production of E. coli O78:K80 ghosts was induced by activating the expression of the E-Lysis gene in the pmET32c vector (Figure 1A)

Summary

Introduction

Avian colibacillosis is one of the most commonly occurring bacterial diseases caused by avian pathogenic Escherichia coli (APEC) [1]. It is a localized or systemic infection that manifests with various signs including, acute fatal septicemia, subacute pericarditis, airsacculitis, and perihepatitis. This infectious disease is generally associated with respiratory disease in poultry flocks, which in severe cases, leads to septicemia and is Soleymani et al Vet Res (2020) 51:144 responsible for a significant proportion of the mortality [1,2,3,4]. Preventive measures that would protect against these three serotypes of avian colibacillosis have the potential to prevent a large number of APEC outbreaks [2]

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