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ARS Home » Southeast Area » Mississippi State, Mississippi » Poultry Research » Research » Research Project #443131

Research Project: Characterization of Avian Pathogenic E. coli Field Isolates and Identification of Potential Vaccine Targets in Commercial Poultry

Location: Poultry Research

Project Number: 6064-13000-014-012-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Sep 15, 2022
End Date: Sep 14, 2027

Objective:
1. Continue characterization of Avian Pathogenic Escherichia coli (APEC) isolates, initiate lethality testing, and identify/screen target antigens for vaccine application. 2. Application of omic techniques to characterize APEC-associated disease factors.

Approach:
Conventional and real-time PCR will be used to confirm putative Avian Pathogenic Escherichia coli (APEC) isolates and to determine serogroup typing and antimicrobial susceptibility. An embryo model will be used to assess APEC isolate virulence. To this end, chicken embryos will be obtained from a specific pathogen-free flock and incubated. Each treatment will have 3 replicate incubators. The injection will occur at 11-18 d of incubation and injection sites will include amnion and yolk sac. Each inoculum will be prepared from overnight cultures and will contain ˜107 cfu/ml. Embryos will be examined daily, and mortality will be recorded. Samples from the amnion and yolk sac will be taken and plated onto McConkey agar plates and incubated overnight at 37°C. Further confirmation and characterization of virulence will be carried out using real-time PCR. Research will be initiated to identify potential immunological targets. The complete genome and plasmid sequence of selected APEC-like strains will be obtained. Gene analysis of putative virulence factors and antibiotic resistance sequenced genomes will be predicted using databases. The conserved core genome of APEC-like strains will be identified using BLAST (Basic Local Alignment Search Tool) to identify essential, virulent, and antigenic proteins. Proteins with the potential for vaccine candidates will then be subjected to antigenicity prediction. The outer membrane proteins and antigenic scores will be determined and proteins will be selected for in vitro and in vivo analyses.