title: In vivo replication of porcine reproductive and respiratory syndrome virus in swine alveolar macrophages and change in the cell population in bronchoalveolar lavage fluid after infection.
abstract: Replication of porcine reproductive and respiratory syndrome (PRRS) virus in swine alveolar macrophages (AM) and cell population in broncho-alveolar lavage fluid (BALF) obtained from PRRS virus-infected pigs were investigated. BALF samples were periodically collected from 6 pigs infected with PRRS virus and 3 non-inoculated control pigs by means of fiber-optic bronchoscope between post-inoculation day (PID) 0 and 56. The mean ratio of macrophages in BALF collected from infected group was 92.7 +/- 3.2% before inoculation and gradually decreased from PID 14. On the other hand, the ratio of lymphocytes was 4.8 +/- 3.2% before inoculation and increased from PID 21 and indicated 41.8 +/- 9.1% on PID 28. After that, they decreased gradually and that of macrophages correspondingly increased. The ratio of neutrophils maintained between 0.7% and 5.1%. The ratios of macrophages, lymphocytes and neutrophils collected from control group were almost stable through the examination. Intracellular PRRS virus antigens in AM were detected from PID 2 by indirect immunofluorescence assay (IIFA). PRRS virus was first isolated from BALF samples collected from inoculated group between PID 2 and 49. From serum, virus was isolated between PID 2 and 21. Antibodies in sera measured by IIFA to PRRS virus were first detected on PID 14 and the antibody titer rose to 1:640 or 1:1,280. The results suggested that PRRS virus replicates in swine AM for a relatively long period.
authors.affiliation: Zen-noh Institute of Animal Health, Chiba, Japan.
authors.forename: I
authors.initials: I
authors.lastname: Shibata
authors.forename: M
authors.initials: M
authors.lastname: Mori
authors.forename: K
authors.initials: K
authors.lastname: Uruno
authors.forename: Y
authors.initials: Y
authors.lastname: Samegai
authors.forename: M
authors.initials: M
authors.lastname: Okada
mesh_terms: D000818:Animals; D018893:Bronchoalveolar Lavage / Q000379:methods / Q000662:veterinary; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology* / Q000821:virology; D008214:Lymphocytes / Q000473:pathology; D016676:Macrophages, Alveolar / Q000473:pathology / Q000821:virology*; D019318:Porcine Reproductive and Respiratory Syndrome / Q000473:pathology / Q000503:physiopathology*; D019316:Porcine respiratory and reproductive syndrome virus / Q000302:isolation & purification / Q000502:physiology*; D013552:Swine; D013997:Time Factors; D014779:Virus Replication