Location: Poultry Research
2017 Annual Report
Objectives
1. Compare and characterize the transmissibility of Mycoplasma gallisepticum (MG) (virulent and attenuated vaccine strains) between birds in different commercial types of housing systems.
2. Identify the genetic and phenotypic differences between virulent and attenuated vaccine strains which may aid in developing an assay that will allow the differentiation of infection from vaccination.
3. Investigate the efficacy of in ovo vaccination strategies to protect against disease caused by MG.
4. Research and develop vaccine platforms that are effective in very young birds, provide cross-protection, and can be easily administered.
5. Use proteomics, genomics, and systems biology approaches to identify molecular determinants of pathogenesis, strain variation, and tissue tropism.
6. Identify immunological targets that will confer cross-protection against prevalent E. coli strains in poultry production.
Approach
To determine the transmissibility of Mycoplasma gallisepticum (MG) under varying conditions relevant to commercial poultry industries, layer chickens will be challenged with virulent and attenuated MG strains and then will be placed among naïve poultry. Transmissibility will be assessed by detection the MG among non-challenged poultry. To determine the impact of housing system on the transmission rates both conventional cage and non-cage systems will be investigated. Further, among conventional cage systems, the ventilation systems will include both still air and tunnel ventilation. Among the non-cage systems, experiments will be designed to compare poultry housed over open pit, deep pit, and flush tank systems to determine any effects on MG transmissibility. To compare genetic and phenotypic differences between virulent and attenuated strains of MG, MG strains will be sequenced and their genome assembled. Further, comparative proteomics will be performed, and all associated findings will be analyzed to elucidate differences which may be applied to future means of MG control. To develop an MG in ovo vaccination protocol and test its’ potential for application towards protection of commercial flocks from MG challenge, experiments will be initially be performed to determine appropriate dosage levels. The effects of the various doses of the MG vaccine on the 18 d embryo will be determined and findings will be applied to the development of a commercially applicable high throughput automated protocol. In addition, chicks derived from the vaccinated eggs will be hatched and assessed for afforded protection. Newly developed vaccine delivery platforms will be used to study their impact on the delivery of the current commercially available E. coli vaccine. The results will be used to develop improved methods of vaccine delivery to very young chickens, including optimized delivery conditions. In order to understand the molecular basis of E. coli pathogenesis in poultry, a selection of pathogenic E. coli strains will be analyzed by genome sequencing and proteomic analysis to identify genotypic and phenotypic differences and similarities. Parallel studies will be performed to identify the antigenic targets that provide cross-protection against E. coli pathogenesis. The combined results from these methodologies will provide the means for developing improved methods of E. coli control.
Progress Report
Some research has been completed towards determining the impact of housing systems and air flow on the transmission rates of 2 strains of Mycoplasma gallisepticum (MG) (Objective 1a). In particular, trials have been completed to assess the transmission of strains F (low virulence) and Rlow (high virulence) at low air flow while trials to assess the effect of high air flow are underway. Investigations on the impact of litter system on the transmission of MG have been initiated. A trial to assess the impact of a flush-type system (Objective 1b) has been completed and the initial trial involving the high-rise type system is currently underway.
Genome sequencing for MG strains ts-11, 6/85, MX-4, and K5234 has been completed as required for Objective 2. Draft genome assemblies and annotations have been generated. Final genome assembly and annotation is in process. This data is required for accurate identification of protein fragments by mass spectrometry, which will be performed during the upcoming 12 month period (24 month milestone). Sequence data will be further analyzed for differences and similarities that can be used for diagnostic purposes and future control strategies.
Progress in addressing in ovo F strain MG vaccination has been made in that hatching of live, vaccinated chicks has occurred.
Accomplishments
