Isolation of a cytopathic virus from weak pigs on farms with a history of swine infertility and respiratory syndrome

• Published in: Journal of veterinary diagnostic investigation Vol. 4; no. 2; p. 139
• Main Authors: Yoon, I.J. (University of Minnesota, St. Paul, MN), Joo, H.S, Christianson, W.T, Kim, H.S, Collins, J.E, Carlson, J.H, Dee, S.A
• Format: Journal Article
• Language: English
• Published: United States 01.04.1992
• Subjects: Animals; Cells, Cultured; CERDO; Cytopathogenic Effect, Viral; CYTOPATHOGENICITY; ENFERMEDADES RESPIRATORIAS; ESTERILIDAD; Female; Fetal Death - microbiology; Fetal Death - veterinary; Fluorescent Antibody Technique; INFERTILITE; INFERTILITY; Infertility, Female - microbiology; Infertility, Female - veterinary; Lung - microbiology; Lung - pathology; Macrophages, Alveolar - microbiology; MALADIE RESPIRATOIRE; MINNESOTA; PATHOGENICITY; PODER PATOGENO; PORCIN; POUVOIR PATHOGENE; Pregnancy; Pregnancy Complications, Infectious - microbiology; Pregnancy Complications, Infectious - veterinary; REPRODUCTIVE DISORDERS; RESPIRATORY DISEASES; Respiratory Tract Infections - microbiology; Respiratory Tract Infections - veterinary; RNA Viruses - isolation & purification; RNA Viruses - physiology; SWINE; Swine Diseases - microbiology; Syndrome; TRASTORNOS DE LA REPRODUCCION; TROUBLE DE LA REPRODUCTION; VIRUS; Virus Diseases - microbiology; Virus Diseases - veterinary; VIRUSES
• ISSN: 1040-6387; 1943-4936
• DOI: 10.1177/104063879200400204

Severe clinical signs of swine infertility and respiratory syndrome (SIRS) of unknown cause were observed in several Minnesota swine farms between November 1990 and March 1991. Forty-five lung samples of weak pigs were collected from 13 swine farms, and virus isolation was attempted using swine alveolar macrophage (SAM) cultures. A cytopathic virus was isolated from 19 lung samples collected from 6 different farms. Four pregnant sows were infected intranasally with a tissue suspension from which virus was isolated, and 4 6-week-old pigs and 2 contact pigs were infected intranasally with 1 of the isolates. The 4 sows farrowed 12 stillborn and 32 normal pigs. Virus was recovered from 10 of 19 pigs examined. Infected 6-week-old pigs were clinically normal except for slightly elevated rectal temperatures and mild respiratory signs. No or mild interstitial pneumonic lesions were observed in inoculated pigs, but the lesion was obvious in the 2 contact pigs. Seroconversion was observed in sows and pigs as measured by indirect fluorescent antibody (IFA). Serologic identification of the isolates was carried out by IFA using reference serum prepared from an experimentally infected sow. A cytoplasmic fluorescence was observed on the SAM monolayers infected with each of the 19 different isolates. Fluorescence was also observed when the monolayers were tested with SIRS virus ATCC VR-2332-infected sow sera. Replication of the isolates was not affected in the medium containing 5-iodo-2'-deoxyuridine but was inhibited by treatment with ether. The isolates were relatively stable at 56 C and did not agglutinate with various erythrocytes tested.