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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Virus and Prion Research » Research » Research Project #432023

Research Project: Non-Antibiotic Strategies to Control Priority Bacterial Infections in Swine

Location: Virus and Prion Research

Project Number: 5030-32000-119-00-D
Project Type: In-House Appropriated

Start Date: Oct 6, 2016
End Date: Oct 5, 2021

Objective:
Objective 1: Determine molecular mechanisms for virulence of bacterial diseases of swine, including the genetic determinants of bacterial virulence of important swine bacterial pathogens such as Haemophilus parasuis and Streptococcus suis through the use of functional genomics and proteomics, and identify the genetic determinants that differentiate human and swine methicillin-resistant Staphylococcus aureus (MRSA) strains. Subobjective 1.1: Identify genetic determinants contributing to the virulence of H. parasuis and S. suis through the use of functional genomics and proteomics. Subobjective 1.2: Identify the genetic determinants that differentiate human and swine MRSA strains. Objective 2: Determine mechanisms of host susceptibility/resistance to bacterial diseases of swine, including the role of coinfections, physiological, and/or environmental factors on development of disease with bacterial pathogens of swine, identify mechanisms of cross protective immunity to important swine bacterial pathogens such as Haemophilus parasuis and Streptococcus suis, and determine the role of biofilms in persistence of pathogens in the respiratory tract of swine. Subobjective 2.1: Determine the role of coinfections, physiological, and/or environmental factors on development of disease with bacterial pathogens of swine. Subobjective 2.2: Identify mechanisms of cross protective immunity to important swine bacterial pathogens such as H. parasuis and S. suis. Subobjective 2.3: Determine the role of biofilms in persistence of pathogens in the respiratory tract of swine. Objective 3: Develop novel non-antibiotic intervention strategies to control bacterial diseases in swine, including the discovery of effective vaccine platforms to prevent the pathogenesis and clinical disease caused by important swine bacterial pathogens such as Haemophilus parasuis and Streptococcus suis, and determine the feasibility of using biotherapeutics to treat or prevent infectious disease in swine. Subobjective 3.1: Discover vaccine platforms to prevent clinical disease caused by important swine bacterial pathogens such as H. parasuis and S. suis. Subobjective 3.2: Determine the feasibility of using biotherapeutics to treat or prevent infectious disease in swine.

Approach:
The first goal for this research plan is to determine molecular mechanisms for virulence of bacterial pathogens of swine. By combining the genomic work we accomplished during the previous project plan with functional genomic and proteomic studies we expect to identify genes and proteins that are expressed by respiratory pathogens during infection of swine. Combining these techniques will help to refine and confirm prospective virulence targets. We will then be able to test whether these potential targets are involved in pathogenesis through virulence testing in our swine models. Results from these studies will lead to an improved understanding of pathogenic mechanisms of infection, as well as provide novel targets for vaccine strategies. The second goal of this research plan is to determine mechanisms of host susceptibility and resistance to bacterial diseases of swine. There are three areas we have chosen to focus on for this objective. First, we plan to examine how environmental and physiologic factors affect the composition of the upper respiratory microbiome and the establishment and maintenance of pathogens at these sites. For this plan we will examine how in feed and parenteral antibiotics that weaned pigs are exposed to affect the respiratory microbiome. Eventually this will lead to future experiments that will examine the effects of physiologic and environmental stressors and coinfections on carriage of respiratory acquired pathogens. Secondly, we will use immunoproteomics to identify potential cross protective immunogens of bacterial pathogens, such as H. parasuis, that have many serotypes. Finally, we will examine the role of biofilms in persistence of pathogens in the respiratory tract of swine. The third goal of this plan is to develop novel non-antibiotic intervention strategies to control bacterial diseases in swine. One obvious method to reduce antibiotic usage is prevention of disease through the development of efficacious vaccines. We will ultimately use results obtained from the first two objectives to help develop broadly efficacious vaccines. We will be focusing largely on developing improved vaccines against H. parasuis and S. suis, two bacteria in which the current vaccines are limited in their efficacy due to a large number of serotypes that are present in the swine population. In addition to vaccines, we will examine the use of immunomodulators as a promising area of therapeutic, prophylactic, and metaphylactic use to prevent and combat infectious disease during periods of peak disease incidence.