Location: Animal Parasitic Diseases Laboratory2013 Annual Report
1a. Objectives (from AD-416):
An important problem with translating the PRSS Host Genetics Consortium (PHGC) mapping results to application is that disease porcine reproductive and respiratory syndrome (PRRS) in the industry is uncontrolled and often occurs in animals with prior or concurrent exposure to other pathogens. All of the previous results are, however, based on a challenge model in clean facilities using naïve pigs and 1 strain of the PRRS virus. Thus, before results can be implemented in industry breeding programs, and to ensure that this selection does not result in negative impacts on response to other diseases, the observed results need to be validated under field conditions and associations with other pathogens assessed. The Cooperator and the assembled team of researchers has the expertise and infrastructure to address the grant objectives: 1) Determine the nature and robustness of the effects of the identified associated genomic regions to infection with other PRRS virus strains and associations with response to other pathogens and vaccines; 2) Validate the effect of the identified genomic regions to disease challenge under field conditions; 3) Develop and implement strategies to educate industry stakeholders on the role of host genotype and on strategies to improve host resistance to the PRRS virus; and 4) Develop and implement strategies to educate the next generation of industry leaders on the role and science of host genetics of resistance to infectious diseases. ARS will actively be involved in grant objectives 1 and 2.
1b. Approach (from AD-416):
For objectives 1 and 2 the Cooperator and the assembled team of researchers will 1) perform new PRRS vaccination trials in nursery pigs and test the effect of vaccination on PRRSvirus (PRRSV) and porcine circovirus (PCV2) challenge; 2) perform single nucleotide polymorphism (SNP) analyses on genomic DNA from samples; 3) conduct genome-wide association analyses based on SNP data; 4) perform gene expression studies using quantitative PCR assays and Transcriptome Sequencing (RNA-seq) analyses of relevant samples; 5) use bioinformatic resources to process genomic data for these analyses; and 6) perform proteomic fluorescent microsphere immunoassays (FMIAs). Overall the studies will test the effect of the alleles on SSC4 and SSCX on responses to vaccination and to combined infection with PRRSV and PCV2, and on swine health in the field.
3. Progress Report:
New trials using commercial pigs of known genotypes have been planned to test the effects of certain genes on swine responses to respiratory pathogens. The targets will be the most economically important pig viruses, porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus (PCV2), causing more that $664 million yearly losses to U.S. pig producers. ARS scientists at the Beltsville Agricultural Research Center (BARC) in Beltsville, Maryland are working with scientists from Iowa State and Kansas State universities to expand their earlier genetic mapping results for PRRS resistance. They will test whether genetic variants, termed alleles, on swine chromosome 4 (SSC4) and SSCX, known to determine responses to PRRSV infection, also will be major influences on responses to PRRS vaccination and to combined infection with PRRSV and PCV2. In addition, they will test effects of these alleles on swine health in the field.