ARS | Publication request: Infection of United States swine with a Chinese highly pathogenic strain of porcine reproductive and respiratory syndrome virus

Submitted to: Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 15, 2012
Publication Date: January 20, 2013
Citation: Guo, B., Lager, K.M., Henningson, J.N., Miller, L.C., Schlink, S.N., Kappes, M.A., Kehrli, Jr., M.E., Brockmeier, S.L., Nicholson, T.L., Yang, H., Faaberg, K.S. 2013. Experimental infection of United States swine with a Chinese highly pathogenic strain of porcine reproductive and respiratory syndrome virus. Virology. 435(2):372-384.

Interpretive Summary: Porcine reproductive and respiratory syndrom virus (PRRSV) is the foremost disease of swine in the United States. In this report, a strain of virus, prevalent in Asia but foreign to the United States, was found to be highly pathogenic to U.S. commercial swine. Specifically, the highly pathogenic (HP) virus was found to replicate to a higher level and, as a result, caused significant weight loss, exacerbated disease due to commensal bacterial sepsis, increased thymic atrophy, and significantly more severe lung lesions in swine that were not seen with U.S prototype strain VR-2332 infection. The results confirm that the HP-PRRSV strains in Asia are also a serious threat to the U.S. swine industry.

Technical Abstract: To assess the pathogenic effects of Type 2 highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) on healthy 10-week old commercial swine in the United States, viral kinetics and resultant disease caused by intranasal inoculation of such virus rescued from an infectious clone of strain JXwn06 (rJXwn06) was fully evaluated. We found that this rescued HP-PRRSV was able to replicate in swine with 100-fold increased kinetics over U.S. Type 2 prototype strain VR-2332. JXwn06 also caused weight loss, exacerbated disease due to commensal bacterial sepsis, increased thymic atrophy, and significantly more severe histopathological lung lesions in pigs exposed to HP-PRRSV that were not seen with VR-2332 infection. Furthermore, detailed cytokine analysis of serum, bronchoalveolar lavage fluid and tracheobronchial lymph node tissue homogenate revealed a striking elevation in levels of cytokines associated with both innate and adaptive immunity in HP-PRRSV infected swine.