Location: Animal Parasitic Diseases Laboratory2011 Annual Report
1a. Objectives (from AD-416)
The current specific aims are: 1) Use genotyping and phenotyping tools to determine if there are host genes that control resistance/susceptibility to porcine respiratory and the reproductive syndrome virus (PRRSV) infection; 2) Verify genetic variation in response to PRRSV, via improved health, survivability and growth; and 3) Identify relative importance of different phenotypes, and their heritability, that predict response to PRRSV infection.
1b. Approach (from AD-416)
This is a multi-year project that is funded by a consortium representing NPB, USDA, universities and private companies. The consortium represents the first-of-its-kind approach to food animal infectious disease research. The objective of this cooperative research project is to. assess the genetic basis of pig responses to porcine reproductive and respiratory syndrome virus (PRRSV) infection, an infection which causes pneumonia and growth retardation in pigs, affecting the respiratory mucosa. The project uses a Nursery Pig Model to assess pig resistance/susceptibility to primary PRRSV infection. Results from the first year have affirmed that there are genetic components involved in controlling the effectiveness of pig responses to PRRSV infection. By continuing these studies the plan is to test a larger number (1500 total over 4 years) of PRRSV infected pigs. Data collected, using a series of defined assays, stored samples for later work and collated data in the PHGC database will enable researchers to verify important genotypes and phenotypes that predict resistance, tolerance or susceptibility to PRRSV infection.
3. Progress Report
The PRRS Host Genetics Consortium (PHGC) has completed 9 infection trials to assess the role of host genetics in PRRSV resistance. With National Pork Board (NPB) funding ARS scientists at Beltsville MD (BARC) are working with Kansas State University (KSU) and Iowa State University (ISU), to collect samples for a detailed phenotype of the role of pig genetics in resistance to Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) infection. Using a Nursery Pig PRRSV infection model 9 infection trials of 200 pigs each had been completed at the KSU biosecure animal facility using high health pigs donated by commercial breeding companies and for PHGC9 by Iowa State Univ. scientists from their low and high feed efficiency pigs. Blood was collected at 10 timepoints; samples [aliquots of 20,000 sera/trial (for virus and proteins), whole blood Tempus tubes (for RNA), tonsils (for persistence virus tests), and ears (for DNA)] were aliquoted and stored in numerous freezers at KSU and BARC. At BARC this year 450 genomic DNA samples were prepared from PHGC 7-8 pigs and their parents. All PHGC data is being stored in the secure, password protected PHGC database at ISU: http://www.animalgenome.org/lunney/index.php. Access to the PHGC database is open to Consortium members who have signed a Cooperative Research and Development Agreement (CRADA) Material Transfer Agreement (MTA) #58-3K95-9-1319 organized by BARC. At KSU blood samples were assayed for viral levels. Other grants associated with this effort and with this ARS project have completed single nucleotide polymorphism chip typing of all PHGC pigs and analyses of whole blood RNA and serum for differences in gene and protein expression during the infection. The PHGC and related projects will help identify the role of host genes in PRRSV resistance or susceptibility as well as in the ability of some pigs to grow normally despite being PRRSV infected. This project should reveal new genes and mechanisms that are associated with PRRS resistance or alternately with increased PRRS susceptibility. Results should help pig breeding companies to identify and provide more disease resistant pigs to producers. This project was monitored through email and phone contact with the participating labs and pig breeding companies discussing project plans and pig availability, reviewing pig sampling and data collection plans, and database design.