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United States Department of Agriculture

Agricultural Research Service

Research Project: INTERVENTION STRATEGIES TO CONTROL VIRAL DISEASES OF SWINE Title: Two Asian highly pathogenic strains of Type 2 PRRSV in United States swine

Authors
item Faaberg, Kay
item Lager, Kelly
item Guo, Baoqing -
item Brockmeier, Susan
item Miller, Laura
item Henningson, Jamie
item Schlink, Sarah
item Kappes, Matthew
item Kehrli Jr, Marcus
item Nicholson, Tracy
item Yang, Han-Chun -

Submitted to: Keystone Symposia
Publication Type: Abstract Only
Publication Acceptance Date: February 14, 2013
Publication Date: April 29, 2013
Citation: Faaberg, K., Lager, K., Brockmeier, S., Guo, B., Swenson, S., Yang, H., Kehrli, M., Nicholson, T., Miller, L., Henningson, J., Schlink, S., Kappes, M. 2013. Two Asian highly pathogenic strains of Type 2 PRRSV in United States swine. Positive Strand RNA Viruses, Keystone Symposia on Molecular and Cellular Biology. Paper No. 1063.

Technical Abstract: Highly pathogenic PRRSV (HP-PRRSV) has been circulating in Asia for 7 years. rJXwn06 and rSRV07 were rescued from infectious clones of two HP-PRRSV for investigation at the National Animal Disease Center. The clinical disease and viral replication kinetics of HP-PRRSV were compared to prototype strain VR-2332. Four-week-old pigs were inoculated intranasally with either a low (2 x 10^3 TCID50) or high (2 x 10^6 TCID50) dose of the rJXwn06, rSRV07, or VR-2332. Swine were monitored for clinical disease and samples collected to assay virus load and host cytokine response. Following rJXwn06 inoculation, rapid onset of disease (fever, weight loss, respiratory distress) occurred that led to death or euthanasia in all low and high dosed swine. The disease in low and high dosed rSVR07 inoculated swine was similar, but less intense. In comparison, VR-2332 challenged swine were mildly affected. The HP-PRRSV inoculated pigs had significant changes in their innate and adaptive cytokine responses when compared to the VR-2332 and control pigs, supported by the isolation of a number of bacterial species from the HP-PRRSV affected pigs in contrast to little or none isolated from the VR-2332 and control swine. In another study, the use of an attenuated PRRSV vaccine (Ingelvac PRRS® MLV) to protect pigs from HP-PRRSV infection was evaluated. Pigs were vaccinated at 4-weeks, and at 10-weeks-of age were challenged intranasally with high doses of the two HP-PRRSV. Vaccination reduced the clinical effect of HP-PRRSV challenged when compared to non-vaccinated challenged controls. However, many of the vaccinated HP-PRRSV challenged swine became very sick with some mortality.

Last Modified: 10/25/2014
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