Do immune genes indicate which pigs will have persistent PRRSV infections?

Authors: Lunney, Joan; ROWLAND, RRR - KANSAS STATE UNIV.; MOLINA, R - IOWA STATE UNIV.; HERMANN, J - IOWA STATE UNIV.; Kuhar, Daniel; CHRISTOPHER, J - SOUTH DAKOTA STATE UNIV; NELSON, E - SOUTH DAKOTA STATE UNIV; LEATHERS, V - IDEXX; ZIMMERMAN, J - IOWA STATE UNIV.

Submitted to: Porcine Reproductive and Respiratory Syndrome International Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 10/1/2006
Publication Date: 12/1/2006
Citation: Lunney, J.K., Rowland, R., Molina, R., Hermann, J., Kuhar, D.J., Christopher, J., Nelson, E., Leathers, V.J., Zimmerman, J. 2006. Do immune genes indicate which pigs will have persistent PRRSV infections? [Abstract]. 2006 International PRRS Symposium. p. 28. Available: http://www.prrssymposium.org/ p. 40

Interpretive Summary:

Technical Abstract: The "Big Pig" project is a multi-disciplinary, multi-institutional approach to 1) establish a better estimate of the proportion of pigs with persistent PRRSV infections and 2) identify virological or immunological correlates of persistent infection or immunity for diagnostic use. This study highlights immune response differences between pigs that have evidence of long term persistent PRRSV infection at >/= 112 days post inoculation (dpi) and compare those responses to control pigs and pigs that apparently cleared the infection in the first 28 dpi. Two-week old pigs (n=109) were inoculated with PRRSV ATCC VR-2332 and 56 age-matched animals served as uninoculated controls. Sets of PRRSV infected and control pigs were euthanized at 2 week intervals through 203 dpi and tissues collected. We prepared RNA from respiratory immune and regional mucosal tissues [lung, tracheobronchial lymph nodes and tonsil]. A panel of 23 immune markers, representing innate, T helper and regulatory genes, were assayed on tissue cDNA from pigs with persistent versus non-persistent PRRSV infections and controls. Low levels of interferon-gamma and certain innate immune genes were expressed by all infected pigs. Final statistical analyses for all tissues are continuing. We hope to determine if there is a pattern of cytokine expression that might help predict which pigs will clear virus, and distinguish them from those that remain persistently infected. A parallel test of serologic cytokine levels is underway. We expect this data will reveal differential gene and protein expression associated with PRRSV clearance and help identify novel regulatory pathways that would stimulate PRRSV immunity. Supported by USDA ARS and NRI PRRS CAP1 funds.