Pathogenesis of porcine reproductive and respiratory syndrome virus infection in gnotobiotic pigs

• Published in: Veterinary pathology Vol. 32; no. 4; p. 361
• Main Authors: Rossow, K.D. (University of Minnesota, St. Paul, MN.), Collins, J.E, Goyal, S.M, Nelson, E.A, Christopher-Hennings, J, Benfield, D.A
• Format: Journal Article
• Language: English
• Published: United States 01.07.1995
• Subjects: ANIMAL DE LABORATOIRE; ANIMAL TISSUES; ANIMALES DE LABORATORIO; Animals; ARTERIVIRUS; Arterivirus Infections - etiology; Arterivirus Infections - veterinary; Arterivirus Infections - virology; AXENIE; Blood Vessels - pathology; CERDO; DISEASE COURSE; Encephalitis - pathology; Encephalitis - veterinary; EXENCION DE PATOGENOS ESPECIFICOS; EXPERIMENTACION IN VIVO; EXPERIMENTAL INFECTION; EXPERIMENTATION IN VIVO; Female; Germ-Free Life; GNOTOBIOTIC ANIMALS; HISTOPATHOLOGIE; HISTOPATHOLOGY; HISTOPATOLOGIA; IN VIVO EXPERIMENTATION; INFECCION EXPERIMENTAL; INFECTION EXPERIMENTALE; LABORATORY ANIMALS; LESION; LESIONES; LESIONS; Lung - pathology; Lung - physiopathology; Lymph Nodes - pathology; Lymphocytes - pathology; Myocarditis - pathology; Myocarditis - veterinary; Palatine Tonsil - pathology; PATHOGENESE; PATHOGENESIS; PATOGENESIS; Pneumonia, Viral - pathology; Pneumonia, Viral - veterinary; PORCIN; Random Allocation; REPLICATION; SHEDDING; SINTOMAS; SPECIFIC PATHOGEN FREE STATE; SWINE; Swine Diseases - etiology; Swine Diseases - pathology; Swine Diseases - virology; SYMPTOME; SYMPTOMS; Syndrome; TEJIDOS ANIMALES; TISSU ANIMAL; TOGAVIRIDAE; Vasculitis - pathology; Vasculitis - veterinary
• ISSN: 0300-9858; 1544-2217
• DOI: 10.1177/030098589503200404

The pathogenesis of porcine reproductive and respiratory syndrome virus (PRRSV) was determined in gnotobiotic pigs by studying the sequential development of microscopic lesions and sites of virus distribution and replication. Thirty-two pigs (three pigs/infected group and one pig/control group) were inoculated by nasal instillation of either PRRSV isolate ATCC VR-2332 (total dose 10(2.6) TCID50) or uninfected cell culture supernatant. Infected and control pigs were euthanized at 12 hours, and 1, 2, 3, 5, 7, 14, and 21 days postexposure (PE). Gnotobiotic pigs experimentally infected with PRRSV were viremic by 12 hours PE and subsequently developed pneumonia, lymphadenopathy, vasculitis, myocarditis and encephalitis. Lung lesions developed by day 3 PE, persisted through day 21 PE and were characterized by alveolar septa thickened by macrophages, alveolar proteinaceous and karyorrhectic debris, alveolar syncytial cells, and multifocal type II pneumocyte hypertrophy. Lymph node lesions varied in distribution and severity and were characterized by germinal center hypertrophy and hyperplasia, lymphocyte necrosis, multiple cystic spaces, and polykaryocytes within the cystic spaces. Heart lesions were a late feature of infection and all infected pigs had heart lesions on day 21 PE characterized by subendocardial, myocardial, and perivascular foci of lymphocytes. Vasculitis also varied in distribution and severity and affected all sizes of vessels. Results of this experiment indicate that PRRSV is a multisystem disease characterized initially by viremia with subsequent virus distribution and replication in multiple organs causing interstitial pneumonia, vasculitis, lymphadenopathy, myocarditis, and encephalitis.