Abstract
Live attenuated vaccines are commonly used to control Mycoplasma gallisepticum infections in chickens. M. gallisepticum ts-304 is a novel live attenuated vaccine strain that has been shown to be safe and effective. In this study, the transcriptional profiles of genes in the tracheal mucosa in chickens challenged with the M. gallisepticum wild-type strain Ap3AS at 57 weeks after vaccination with ts-304 were explored and compared with the profiles of unvaccinated chickens that had been challenged with strain Ap3AS, unvaccinated and unchallenged chickens, and vaccinated but unchallenged chickens. At two weeks after challenge, pair-wise comparisons of transcription in vaccinated-only, vaccinated-and-challenged and unvaccinated and unchallenged birds detected no differences. However, the challenged-only birds had significant up-regulation in the transcription of genes and enrichment of gene ontologies, pathways and protein classes involved in infiltration and proliferation of inflammatory cells and immune responses mediated through enhanced cytokine and chemokine production and signaling, while those predicted to be involved in formation and motor movement of cilia and formation of the cellular cytoskeleton were significantly down-regulated. The transcriptional changes associated with the inflammatory response were less severe in these mature birds than in the relatively young birds examined in a previous study. The findings of this study demonstrated that vaccination with the attenuated M. gallisepticum strain ts-304 protects against the transcriptional changes associated with the inflammatory response and pathological changes in the tracheal mucosa caused by infection with M. gallisepticum in chickens for at least 57 weeks after vaccination.
Highlights
Mycoplasma gallisepticum is the primary etiological agent of chronic respiratory disease (CRD) in chickens
In order to further understand the protective immunity offered by this new vaccine strain, we explored the transcriptional profiles of the tracheal mucosa in chickens challenged with the M. gallisepticum wild-type strain Ap3AS at 57 weeks after vaccination and compared these to the profiles of unvaccinated chickens of a similar age that had been infected with strain Ap3AS
This study explored the transcriptional profile of the tracheal mucosa of chickens after vaccination with the ts-304 live attenuated vaccine against M. gallisepticum and/or infection with virulent M. gallisepticum
Summary
Mycoplasma gallisepticum is the primary etiological agent of chronic respiratory disease (CRD) in chickens. The consequent reduced feed consumption, decreased egg production and slower weight gain cause significant economic loss in both egg and meat producing poultry [4,5,6]. The most effective control measure is maintenance of diseasefree flocks by adhering to strict biosecurity, with periodic serological testing and immediate culling of infected flocks [7]. Administration of antimicrobial drugs in the feed or water and vaccination are effective approaches to control of disease in those large-scale commercial poultry farms in which maintenance of disease-free flocks is not feasible [8]. Inactivated vaccines reduce clinical signs of the disease and production losses, but offer minimal protection against infection [9]. Several live attenuated vaccines, including F strain [7], strain 6/85 [10] and ts-11 [11] are used to immunize chickens against M. gallisepticum and have been shown to have greater efficacy in prevention of mycoplasmosis than killed vaccines [12]
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