title: Comparison of experimental infection with northern and southern Vietnamese strains of highly pathogenic porcine reproductive and respiratory syndrome virus.
abstract: The aim of this study was to compare the virulence of northern and southern Vietnamese strains of highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) as assessed by the level of viral replication, gross and microscopical lung lesions and virus distribution in experimentally infected pigs. The northern and southern Vietnamese HP-PRRSV strains share 96.7% (non-structural protein 2) and 99.3% (open reading frame 5) nucleotide identity. On experimental challenge, approximately 50% of pigs infected with northern Vietnamese HP-PRRSV died, while death was not observed in any pigs infected with southern Vietnamese HP-PRRSV. Mean viral titres (expressed as log(10)TCID(50)/ml) were significantly (P <0.05) higher in sera and lungs from pigs infected with the northern Vietnamese HP-PRRSV than from those infected with the southern Vietnamese strain at multiple time points. Lung lesion scores and PRRSV antigen within pulmonary and lymphoid lesions were significantly (P <0.05) higher in pigs infected with northern Vietnamese HP-PRRSV than in those receiving southern Vietnamese HP-PRRSV at multiple time points. PRRSV antigens were observed in cardiac myocytes, gastric and renal tubular epithelial cells and astrocytes and microglia of white matter in the brain from pigs infected with the northern Vietnamese HP-PRRSV strain only. Thus, genetic similarity did not predict the degree of virulence of these strains. Northern Vietnamese HP-PRRSV was more virulent and had extended tissue tropism when compared with southern Vietnamese HP-PRRSV.
authors: Seoul National University, Department of Veterinary Pathology, College of Veterinary Medicine, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, Republic of Korea; Faculty of Animal Husbandry and Veterinary Medicine, Nonglam University, Thu Duc District, Ho Chi Minh City, Vietnam.
authors: T D
authors: TD
authors: Do
authors: Seoul National University, Department of Veterinary Pathology, College of Veterinary Medicine, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, Republic of Korea.
authors: C
authors: C
authors: Park
authors: Seoul National University, Department of Veterinary Pathology, College of Veterinary Medicine, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, Republic of Korea.
authors: K
authors: K
authors: Choi
authors: Seoul National University, Department of Veterinary Pathology, College of Veterinary Medicine, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, Republic of Korea.
authors: J
authors: J
authors: Jeong
authors: Faculty of Animal Husbandry and Veterinary Medicine, Nonglam University, Thu Duc District, Ho Chi Minh City, Vietnam.
authors: T T
authors: TT
authors: Nguyen
authors: Faculty of Animal Husbandry and Veterinary Medicine, Nonglam University, Thu Duc District, Ho Chi Minh City, Vietnam.
authors: D Q
authors: DQ
authors: Nguyen
authors: Faculty of Animal Husbandry and Veterinary Medicine, Nonglam University, Thu Duc District, Ho Chi Minh City, Vietnam.
authors: T H
authors: TH
authors: Le
authors: Seoul National University, Department of Veterinary Pathology, College of Veterinary Medicine, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, Republic of Korea. Electronic address: swine@snu.ac.kr.
authors: C
authors: C
authors: Chae
mesh_terms: D000818:Animals; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D016133:Polymerase Chain Reaction; D019318:Porcine Reproductive and Respiratory Syndrome / Q000473:pathology / Q000821:virology*; D019316:Porcine respiratory and reproductive syndrome virus / Q000235:genetics / Q000472:pathogenicity*; D013552:Swine; D013553:Swine Diseases / Q000821:virology*; D014774:Virulence
keywords: highly pathogenic porcine reproductive and respiratory syndrome virus; pathogenicity; pig; respiratory disease