title: Comparative Respiratory Pathogenicity and Dynamic Tissue Distribution of Chinese Highly Pathogenic Porcine Reproductive and Respiratory Syndrome Virus and its Attenuated Strain in Piglets.
abstract: The outbreak of highly pathogenic porcine reproductive and respiratory syndrome (HP-PRRS) in 2006 devastated the Chinese swine industry. HP-PRRS virus is still the predominant strain in mainland China, rather than the classical PRRSV strain, and the attenuated live vaccine remains the preferred choice for protecting piglets against HP-PRRSV infection. To fully evaluate the safety of strain GDr180, the 180th attenuated virus of the HP-PRRSV strain GD, we used clinicopathological, microscopical, ultrastructural, serological and molecular biological methods to assess the different clinical manifestations and respiratory characteristics of piglets inoculated with HP-PRRSV strain GD or strain GDr180. The 5-week-old piglets inoculated with strain GD displayed marked clinical signs, including fever, anorexia, dyspnoea and tachypnoea. Significant interstitial pneumonia was present, characterized by thickened alveolar septa infiltrated with mononuclear cells and cell debris. However, the piglets inoculated with strain GDr180 and the negative control piglets showed neither clinical signs nor microscopical or ultrastructural lesions. Ultrastructural observation of the piglets' tracheas and examination of the dynamic tissue distributions of PRRSV strain GD and attenuated strain GDr180, by immunohistochemistry and fluorescence quantitative reverse transcription-polymerase chain reaction, confirmed significant differences in their pathogenicity and distribution in the respiratory systems of piglets. The differences in pathogenicity are attributable to the different severity of the pathological changes in the pigs inoculated with the two strains. Thus, the HP-PRRSV GDr180 strain is practically harmless to the respiratory systems of piglets and may be a safe candidate for inducing immunity against HP-PRRS.
authors.affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing, PR China; Department of Inspection Technology Research, China Institute of Veterinary Drug Control, No. 8 Zhongguancun South Street, Beijing, PR China.
authors.forename: C
authors.initials: C
authors.lastname: Liu
authors.affiliation: Department of Inspection Technology Research, China Institute of Veterinary Drug Control, No. 8 Zhongguancun South Street, Beijing, PR China.
authors.forename: W
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Department of Inspection Technology Research, China Institute of Veterinary Drug Control, No. 8 Zhongguancun South Street, Beijing, PR China.
authors.forename: W
authors.initials: W
authors.lastname: Gong
authors.affiliation: Department of Inspection Technology Research, China Institute of Veterinary Drug Control, No. 8 Zhongguancun South Street, Beijing, PR China.
authors.forename: D
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing, PR China.
authors.forename: R
authors.initials: R
authors.lastname: She
authors.affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing, PR China. Electronic address: xubr@sina.com.
authors.forename: B
authors.initials: B
authors.lastname: Xu
authors.affiliation: Department of Inspection Technology Research, China Institute of Veterinary Drug Control, No. 8 Zhongguancun South Street, Beijing, PR China. Electronic address: ningyibao@sina.com.
authors.forename: Y
authors.initials: Y
authors.lastname: Ning
mesh_terms: D000818:Animals; D007150:Immunohistochemistry; D019318:Porcine Reproductive and Respiratory Syndrome / Q000473:pathology* / Q000517:prevention & control / Q000821:virology*; D019316:Porcine respiratory and reproductive syndrome virus / Q000235:genetics / Q000472:pathogenicity*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013552:Swine; D014765:Viral Vaccines
chemical_list: D014765:Viral Vaccines
keywords: attenuated virus; dynamic distribution; pathogenicity; porcine reproductive and respiratory syndrome