Location: Animal Parasitic Diseases Laboratory
2023 Annual Report
Objectives
Objective 1: Develop immunologic tools to evaluate swine immunity.
Sub-objective 1.A: Develop immunological assays and validate their use for assessing host immune responses to infectious diseases and vaccination.
Sub-objective 1.B: Use immunological tools to inform the design of novel innate immune intervention strategies to treat respiratory diseases of swine.
Objective 2: Elucidate immune and genomic determinants of host responses associated with porcine reproductive and respiratory syndrome virus infection.
Sub-objective 2.A: Discover genetic and biological determinants associated with fetal susceptibility, resilience, or resistance to porcine reproductive and respiratory syndrome.
Sub-objective 2.B: Discover genetic and biological determinants associated with good responders to porcine reproductive and respiratory syndrome vaccines.
Approach
This project will produce new reagents for analyses of swine immunity. This will include characterization of monoclonal antibodies (mAbs) reactive with swine cytokines and chemokines and development of assays that quantify their reactivity. These efforts will be coupled with NIFA grant supported Swine Toolkit efforts. Once characterized commercial access to these mAbs will be coordinated through ARS Technology Transfer Office. Basic studies will be expanded by establishing molecular tools to evaluate gene expression using NanoString Technologies, with codesets developed to explore relative importance of specific tissues and unique cell subsets in disease responses and pathogen resistance. These tools will help to identify alternate biomarkers for risk analyses to assess the impact of respiratory diseases and vaccine efficacy.
This project will apply the use of these innovative, next-generation, genomic, transcriptomic, and immunologic techniques to address Porcine Reproductive and Respiratory Syndrome (PRRS), focusing on our unique sample resources collected via the PRRS Host Genetics Consortium and the Canadian Pregnant Gilt Model projects. We will evaluate the influence of host genetics on antiviral response pathways and will aim to identify critical biomarkers of protective vaccine and infection responses. We will use RNAseq data analyses to provide a more complete picture and reveal details of regulatory mechanisms impacting pig responses to vaccination, viral infection, and differential growth effects. Advanced bioinformatics will be combined with new molecular studies, as well as previously collected genotypic and phenotypic data, to identify pathways and biomarkers associated with protective immune responses to respiratory and reproductive diseases that cause significant losses to the pork industry.
This project will provide alternate resources for improved respiratory disease control and elimination strategies. Overall, our project will inform vaccine evaluation and virus control strategies, identify disease-resistant pigs, and stimulate advances that may be of broad economic importance to pig breeders and the animal health industry.
Progress Report
This project’s first objective focuses on the development of new reagents for swine immunity. Scientists at Beltsville, Maryland, obtained cloned and expressed swine immune proteins (cytokines, chemokines) from a commercial partner; another commercial partner developed monoclonal antibodies (mAbs) to these proteins. We characterized reactivities of panels of resultant mAbs reactive with different swine interleukins and chemokines. In collaboration with ARS and university partners, we tested cells for intracellular staining. Subsets of these mAbs have been commercialized and shared with colleagues internationally. These mAbs enable researchers to quantify the effects of specific immune proteins and cell subsets in experimental verification of swine immune, disease, and vaccine responses as well as for basic porcine biomedical research efforts worldwide.
This project’s second objective focuses on porcine reproductive and respiratory syndrome (PRRS) which causes an estimated $600 million in annual losses to the U.S. pig industry. ARS scientists in Beltsville, Maryland, are working with university scientists to probe fetal responses to congenital PRRS virus infection. These responses can vary greatly within fetuses in litters from PRRS virus infected sows. Litters can include uninfected fetuses with neighboring dead fetuses or those harboring high viral levels. We have concentrated on maternal and fetal factors that predict disease severity and fetal resilience, the capacity of a fetus to resist infection. Using tissues, collected from fetuses of late term PRRS virus infected sows, we are testing RNA gene expression with focused NanoString codesets. Our aim is to identify specific genes that are expressed by resilient fetuses; these could then be used as biomarkers for selecting PRRS resistant breeding stock.
In FY23 the Lead Scientist, Dr. Joan Lunney, was a U.S. Presidential Rank Award winner as a Meritorious Senior Professional (2022).
Accomplishments
1. New genetic markers for swine viral disease resistance. Porcine reproductive and respiratory syndrome (PRRS) causes an estimated $600 million in annual losses to the U.S. pig industry. Better understanding of why some pigs resist or succumb to disease can mitigate this problem. Therefore, ARS scientists in Beltsville, Maryland, worked with university scientists to probe both fetal responses to congenital PRRS virus infection and nursery pig responses to PRRSV infection. We discovered genomic control of serum thyroid hormone levels in infected piglets and fetuses. Pinpointing the responsible genes advances understanding of piglet and fetal response to PRRSV infection and will benefit pig breeders, pig farmers, and veterinarians as they seek to enhance resilience and reduce susceptibility.
2. Affirmed the importance of interagency partnerships. The USDA National Institute of Food and Agriculture (NIFA) and the National Institutes of Health (NIH) established an interagency “Dual Purpose” partnership to promote the use of agriculturally important animal species in basic and translational research relevant to both biomedicine and agriculture. Increased knowledge of reproduction and health of domesticated animals is integral to sustain and improve global competitiveness of U.S. animal agriculture. The successes of “Dual Purpose” funding highlighted key advantages of farm animal models for simultaneously addressing biomedical and agricultural challenges. The recommendations highlight opportunities for future interagency partnerships, and grant programs among federal agencies, utilizing domesticated agricultural animals in research.
3. Confirmed reactivity of tools to evaluate swine immunity. Researchers lack sufficient commercial reagents to probe pig immunity and host responses to pathogen infections and vaccines. Therefore, ARS scientists in Beltsville, Maryland, worked with university partners to characterize monoclonal antibodies that bind important swine immune proteins (interleukins and chemokines). They showed that one such antibody (which binds the chemokine CXCL10) performs well against live and fixed tissues, meaning that the reagent offers broad utility for a range of research pursuits. By transferring several anti-swine immune protein antibodies to companies and collaborators, the USDA team enhanced means to access and use these new research tools. These tools will elucidate mechanisms underlying pig responses to pathogens and lead to the design of more effective diagnostics, therapeutics, and vaccine interventions.
Review Publications
Van Goor, A.G., Pasternak, A., Walugembe, M., Chehab, N.L., Hamonic, G., Dekkers, J., Harding, J., Lunney, J.K. 2023. Genome wide association study of thyroid hormone levels following challenge with porcine reproductive and respiratory syndrome virus. Frontiers in Genetics. 14. Article 1110463. https://doi.org/10.3389/fgene.2023.1110463.
Spencer, T.E., Wells, K.D., Lee, K., Telugu, B.P., Hansen, P.J., Bartol, F.F., Blomberg, L., Schook, L.B., Dawson, H.D., Lunney, J.K., Driver, J.P., Davis, T.A., Donovan, S.M., Dilger, R.N., Saif, L.J., Moeser, A., McGill, J.L., Smith, G., Ireland, J.J. 2022. Future of biomedical, agricultural and biological systems research using domesticated animals. Biology of Reproduction. 106(4):629-638. https://doi.org/10.1093/biolre/ioac019.
