Evaluation of the Pathogenicity of a Highly Pathogenic Porcine Reproductive and Respiratory Syndrome Virus Variant in Piglets |
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Authors: | WEI Tian-chao TIAN Zhi-jun ZHOU Yan-jun AN Tong-qing JIANG Yi-feng XIAO Yan HUShou-ping PENG Jin-mei HAO Xiao-fang ZHANG Shan-rui TONG Guang-zhi |
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Affiliation: | 1. State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences,Harbin 150001, P.R.China ;College of Animal Science and Technology, Guangxi University, Nanning 530005, P.R.China 2. State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences,Harbin 150001, P.R.China 3. Division of Swine Infectious Diseases, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200241, P.R.China 4. State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences,Harbin 150001, P.R.China ;Division of Swine Infectious Diseases, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200241, P.R.China |
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Abstract: | Since May 2006,a highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) variant characterized by 30 amino acids deletion within its NSP2-coding region emerged and caused extensive economic losses to China's pig industry.To investigate the in vivo pathogenicity and immune responses of the newly emerging PRRSV,3 groups of 60-d-old conventional piglets were inoculated intranasally with a representative strain of the HP-PRRSV variant HuN4 with 3 different infection doses (3× 103-3× 105 TCID50).The results revealed that the virus variant caused severe disease in piglets and the significant clinical characteristics consisted of persistently high fever (41.0-41.9℃) and high morbidity and mortality (60-100%),the marked clinical signs of PRRS and severe histopathogenic damages in multiple organs.It induced rapid and intense humoral immune responses and seroconversion was detected in most infected pigs at 7 d post-infection (DPI).The virus vigorously replicated in vivo and the highest virus average titer was 9.7 log copies mL-1 serum at 7 DPI.Elevated levels of IFN-y and IL- 10 cytokine production in serum in this study were also observed.Taken together,our results demonstrated that the HP-PRRSV variant HuN4 strain is highly pathogenic for piglets and suitable to be a reference strain of highly virulent PRRSV for evaluating the efficacy of the new vaccines. |
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Keywords: | highly pathogenic porcine reproductive and respiratory syndrome virus pathogenicity immune responses viral load |
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