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Researcher: Dr. Anup Kollanoor Johny (Interventional Microbiologist), University of Minnesota
Co-Investigator: Dr. Sally Noll (Turkey Nutrition and Management), University of Minnesota
Postdoctoral Researcher: Dr. Luna Akhtar (Phage biologist, Johny lab)
Industry Partners: Dr. Petri Papinaho (Jennie-O), Dr. Michelle Kromm (Jennie-O)
MTRPC funding amount: $66,000
Goals:
The overall goal of this integrated project is to develop integrator-friendly, farm-derived bacteriophage cocktails, and vaccination in combination against Salmonella serovars in turkey production.
Specific Objectives:
Expected Deliverables:
Final Report: December 2024
Major Goal:
To develop novel bacteriophage cocktails against Salmonella serotypes alone or in combination with Salmonella vaccination in turkey production.
Impact of the study:
Two custom bacteriophage cocktails highly effective against field strains of Salmonella Reading were developed and tested successfully in adult turkeys.
Producer-focused project summary:
Salmonella, a major bacterium causing human foodborne illnesses, is a constant threat to the turkey industry. The major contributing factor to this issue is the colonization of turkeys with different serotypes of Salmonella with potential to end up in products. This MTRPC-funded project targeted several emerging types of Salmonella relevant to turkey production for screening tests to develop novel bacteriophage cocktails and test them against field strains of Salmonella Reading in turkeys along with a Salmonella vaccine. This is important for our turkey producers because multiple types of Salmonella could be present at one time in flocks, and better farm-friendly and economical strategies against Salmonella are required. Our results indicate that when we develop the correct phage mix with appropriate outcomes in mind, a consistent and meaningful reduction of Salmonella without affecting the body weight should be obtained. This approach will be helpful for our producers since phage-based Salmonella control strategy, once developed, can be highly economical for flock-friendly use.
Background of the project:
Salmonella has been a constant threat to the safety of our food supply, including turkeys. The problem is worsened due to the emerging types of Salmonella in turkey production, in addition to the common types. The industry is adopting measures to control these salmonellae; however, we need more effective alternatives for production use. Our team has been successful in testing a USDA-approved Salmonella vaccine in commercial turkeys against multiple Salmonella (some results are published, and some projects are active). We are also validating a novel bacteriophage-based drug development pipeline with less impact on the environment. The novel cocktails along with the vaccine, was tested against Salmonella Reading in this study.
The procedure employed in the project:
A. Development of phage cocktails and characterization:
Several samples of turkey ceca from processing and phage-harboring environments were screened during the study period. Due to Avian Influenza, we could not obtain farm samples for bacteriophage isolation. We had to extend our isolation strategy toother environmental sources. A total of 23 strains of Salmonella, including 9 strains of S. Reading, were used to screen the potential phages to lyse them. Phages were isolated and processed phenotypically. After these assessments, multiple cocktails against single or multiple serotypes of Salmonella, with a focus on S. Reading, were developed.
B. Testing of phage cocktails in turkeys:
Two, 11-week-longstudies in turkeys were completed. In each study, day-old poults were randomly assigned to seven treatment groups at the poultry barn with age-appropriate management procedures. The treatment groups were: Group 1 - Negative Control (NC-birds with no treatment or Salmonella challenge serving as industry performance group), Group 2 - Positive Control (PC-birds with Salmonella infection but no treatments),Group 3 - Vaccine Control (VC-birds challenged with Salmonella and vaccine), Group 4 (UMNØ1 - phage 1 cocktail and Salmonella challenge), Group 5 (UMNØ1VC - phage 1 cocktail, Salmonella challenge, and vaccine),Group 6 (UMNØ2 - UMN Phage 2 cocktail and Salmonella challenge), Group 7 (UMNØ2VC - Phage 2 cocktail, Salmonella challenge, and vaccine). This is a very complex turkey challenge model. The birds in the vaccination groups (groups 3, 5, 7) were vaccinated using Megan Egg (Elanco). At 10 weeks, turkeys were transferred to the isolation barns. All groups were inoculated with field strains of Salmonella Reading using the oral gavage method. The birds were given appropriate phage cocktails at there searched dose rate by UMN investigators. Birds in groups 1 and 2 did not receive phages. All birds were euthanized for sample collection after 7 days of the challenge.
Results:
We developed two bacteriophage cocktails highly effective inactivating all the S. Reading strains used in the study. The results from objective 1 were used to test the efficacy of bacteriophage cocktails against S. Reading in adult turkeys. The results from Objective 2 (in live turkeys) are given below (Figures 1, 2, and 3).
Fig 1 represents the effect of various phage treatments against S. Reading after challenge in turkeys. PC (black bar) yielded 3 log10 CFU/g of S. Reading in turkey cecum. VC and UMNØ1 did not yield a significant reduction of S. Reading, however, numerical reduction was observed (orange and green bar, respectively). However, UMNØ2 independently (purple bar), and in combination with vaccination (red bar), and UMNØ1 with vaccine (blue bar) yielded ~2 log10CFU/g of reduction of S. Reading.
Fig 2 represents the effect of various phage treatments against S. Reading dissemination to the liver of turkeys. PC had all liver samples tested positive for Salmonella. When independent phage treatments yielded nearly 50% samples negative for S. Reading in the liver (green and purple bars), all vaccine treatments completed inhibited S. Reading dissemination to the liver (no bars seen).
Fig 3 represents the effect of various treatments on the bodyweights of turkeys. None of the treatments were significantly different from each other, indicating that the phage treatments yielded similar bodyweights compared to the controls and vaccinated birds.
