title: Apoptosis in the lungs of pigs infected with porcine reproductive and respiratory syndrome virus and associations with the production of apoptogenic cytokines.
abstract: Apoptosis was studied in the lungs of pigs during an infection with a European strain of porcine reproductive and respiratory syndrome virus (PRRSV) and it was examined if cytokines were involved in the induction of apoptosis. Twenty-two 4- to 5-week-old gnotobiotic pigs were inoculated intranasally with 10(6.0) TCID50 of the Lelystad virus and euthanised between 1 and 52 days post inoculation (PI). The lungs and broncho-alveolar lavage (BAL) cells were assessed both for virus replication and apoptosis; BAL fluids were examined for interleukin (IL)-1, tumour necrosis factor-alpha and IL-10. Double-labellings were conducted to determine the relation between virus replication and apoptosis and to identify the apoptotic cells. Apoptosis occurred in both infected and non-infected cells. The percentages of infected cells, which were apoptotic, ranged between 9 and 39% in the lungs and between 13 and 30% in the BAL cells. The majority of apoptotic cells were non-infected. Non-infected apoptotic cells in the lungs were predominantly monocytes/macrophages, whereas those in the broncho-alveolar spaces were predominantly lymphocytes. The peak of apoptosis in the lungs at 14 days PI was preceded by a peak of IL-1 and IL-10 production at 9 days PI, suggesting a possible role of these cytokines in the induction of apoptosis in non-infected interstitial monocytes/macrophages. However, the latter hypothesis was not confirmed in vitro, since blood monocytes or alveolar macrophages did not undergo apoptosis after treatment with recombinant porcine IL-1 or IL-10.
authors.affiliation: Laboratory of Virology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Labarque
authors.forename: Steven
authors.initials: S
authors.lastname: Van Gucht
authors.forename: Hans
authors.initials: H
authors.lastname: Nauwynck
authors.forename: Kristien
authors.initials: K
authors.lastname: Van Reeth
authors.forename: Maurice
authors.initials: M
authors.lastname: Pensaert
mesh_terms: D000818:Animals; D017209:Apoptosis; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry / Q000166:cytology; D007375:Interleukin-1 / Q000378:metabolism / Q000494:pharmacology; D016753:Interleukin-10 / Q000378:metabolism / Q000494:pharmacology; D008168:Lung / Q000473:pathology* / Q000821:virology*; D016676:Macrophages, Alveolar / Q000187:drug effects; D009000:Monocytes / Q000187:drug effects; D019318:Porcine Reproductive and Respiratory Syndrome / Q000473:pathology*; D019316:Porcine respiratory and reproductive syndrome virus / Q000502:physiology*; D013552:Swine / Q000821:virology; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D014779:Virus Replication
chemical_list: D007375:Interleukin-1; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10