Differential production of proinflammatory cytokines in the pig lung during different respiratory virus infections: correlations with pathogenicity.
The acute stages of infection with swine influenza virus (SIV), porcine respiratory coronavirus (PRCV) and porcine reproductive-respiratory syndrome virus (PRRSV) were shown to differ in terms of clinical and lung inflammatory effects and proinflammatory cytokine profiles in bronchoalveolar lavage (BAL) fluids. Caesarian-derived colostrum-deprived pigs were inoculated intratracheally with one of the three viruses. SIV infection was followed within 1 day post inoculation (d PI) by characteristic respiratory and general signs, and excessive lung epithelial desquamation and neutrophil infiltration (38 to 56 per cent of BAL cells at 1 d PI vs 0 to 1 per cent in controls). High concentrations of bioactive interferon-alpha (IFN -alpha), tumour necrosis factor-alpha (TNF -alpha) and interleukin-1 (IL -1) coincided with peak symptoms and neutrophil infiltration. PRCV infection was asymptomatic and produced a mild bronchointerstitial pneumonitis and neutrophil infiltration (13 to 22 per cent of BAL cells at 4 d PI). IFN -alpha titres parallelled those found during SIV infection, TNF -alpha was negligible and IL -1 undetectable. PRRSV infection induced anorexia and lethargy between 3 and 5 d PI. There was marked infiltration with mononuclear cells in alveolar septa and BAL fluids between 7 and 10 d PI, while neutrophils remained at less than 11 per cent of BAL cells at any time. IL -1 was produced from three throughout 10 d PI, while IFN -alpha production was minimal and TNF -alpha undetectable. These data strongly suggest that proinflammatory cytokines can be important mediators of viral respiratory disease.
Van Reeth
K
K
Laboratory of Veterinary Virology, Faculty of Veterinary Medicine, Salisburglaan, Merelbeke, B-9820, Belgium.
Labarque
G
G
Nauwynck
H
H
Pensaert
M
M
D000818:Animals; D001992:Bronchoalveolar Lavage Fluid; D017934:Coronavirus / Q000472:pathogenicity / Q000502:physiology; D018352:Coronavirus Infections / Q000378:metabolism / Q000662:veterinary* / Q000821:virology; D016207:Cytokines / Q000096:biosynthesis*; D009980:Influenza A virus / Q000472:pathogenicity / Q000502:physiology; D008168:Lung / Q000378:metabolism / Q000821:virology*; D009976:Orthomyxoviridae Infections / Q000378:metabolism / Q000662:veterinary* / Q000821:virology; D019318:Porcine Reproductive and Respiratory Syndrome / Q000378:metabolism*; D019316:Porcine respiratory and reproductive syndrome virus / Q000472:pathogenicity / Q000502:physiology; D013552:Swine; D013553:Swine Diseases / Q000378:metabolism* / Q000821:virology*; D014779:Virus Replication
D016207:Cytokines