A comparative study of the local cytokine response in the lungs of pigs experimentally infected with different PRRSV-1 strains: upregulation of IL-1α in highly pathogenic strain induced lesions.
Porcine reproductive and respiratory syndrome viruses (PRRSV) show high genetic differences both among and within genotypes. Recently, several highly pathogenic PRRSV (HP-PRRSV) strains have been described. This study compares and characterizes the production of cytokines by pulmonary macrophages in pigs experimentally infected with four different PRRSV-1 strains: two low-virulent strains, Lelystad (LV) and a British field strain (215-06); a HP strain (SU1-bel) from Belarus and the attenuated vaccine strain DV (Porcilis(®) PRRS). Animals were clinically monitored and post-mortem examinations were performed at 3, 7 and 35 days post-infection (dpi). Lung samples were processed for histopathological and immunohistochemical studies by using specific antibodies against PRRSV, IL1-α, IL-6, TNF-α, IL-10 and IFN-γ. SU1-bel infected animals presented the highest mean scores for clinical observations, gross and microscopic lesions as well as for PRRSV expression compared with the other infected groups (p≤0.027). These animals displayed the highest expression of IL1-α at 7dpi, together with the highest score for lung pathology, whereas LV, 215-06 and DV inoculated animals only showed a transient enhancement in some of these cytokines. SU1-bel-infected pigs showed a positive correlation between the amount of PRRSV antigen and IL-1α expression (r=0.645, p<0.001). The highest expression of IL-10 was detected in 215-06-infected animals (p≤0.004), with a positive correlation with the numbers of virus-infected cells (r=0.375, p≤0.013). In conclusion, the HP-PRRSV SU1-bel strain replicated more efficiently in the lung of infected animals and induced a higher expression of IL-1α than the other PRRSV-1-infected groups, which may have played a key role in the onset of the clinical signs and interstitial pneumonia.
Department of Anatomy and Comparative Pathology, Faculty of Veterinary Medicine, Campus Universitario de Rabanales, 'International Excellence Agrifood Campus, CeiA3', 14071 Cordoba, Spain. Electronic address: ashyrleypaola@yahoo.com.
Shyrley P
SP
Amarilla
CICAP - Food Research Centre, 14400 Pozoblanco, Córdoba, Spain.
Jaime
J
Gómez-Laguna
Department of Anatomy and Comparative Pathology, Faculty of Veterinary Medicine, Campus Universitario de Rabanales, 'International Excellence Agrifood Campus, CeiA3', 14071 Cordoba, Spain.
Librado
L
Carrasco
Department of Anatomy and Comparative Pathology, Faculty of Veterinary Medicine, Campus Universitario de Rabanales, 'International Excellence Agrifood Campus, CeiA3', 14071 Cordoba, Spain.
Irene M
IM
Rodríguez-Gómez
Department of Statistics, Econometrics, Operations Research, Business Organization and Applied Economics, Faculty of Law and Economics, 14071 Cordoba, Spain.
José M
JM
Caridad Y Ocerín
Department of Virology, Animal Health and Veterinary Laboratories Agency-Weybridge, Addlestone, Surrey KT15 3NB, UK.
Sophie B
SB
Morgan
Department of Virology, Animal Health and Veterinary Laboratories Agency-Weybridge, Addlestone, Surrey KT15 3NB, UK.
Simon P
SP
Graham
Department of Virology, Animal Health and Veterinary Laboratories Agency-Weybridge, Addlestone, Surrey KT15 3NB, UK.
Jean-Pierre
JP
Frossard
Department of Virology, Animal Health and Veterinary Laboratories Agency-Weybridge, Addlestone, Surrey KT15 3NB, UK.
Trevor W
TW
Drew
Department of Virology, Animal Health and Veterinary Laboratories Agency-Weybridge, Addlestone, Surrey KT15 3NB, UK; Department of Pathology and Infectious Diseases, School of Veterinary Medicine, University of Surrey, Guildford GU2 7TE, UK.
Francisco J
FJ
Salguero
D000818:Animals; D000956:Antigens, Viral / Q000097:blood; D016207:Cytokines / Q000096:biosynthesis*; D053582:Interleukin-1alpha / Q000096:biosynthesis*; D008168:Lung / Q000276:immunology* / Q000473:pathology; D019318:Porcine Reproductive and Respiratory Syndrome / Q000276:immunology*; D019316:Porcine respiratory and reproductive syndrome virus / Q000276:immunology; D013552:Swine; D015854:Up-Regulation
D000956:Antigens, Viral; D016207:Cytokines; D053582:Interleukin-1alpha
Cytokines; Highly pathogenic porcine reproductive and respiratory syndrome (HP-PRRSV); IL-1α; Lung; PRRSV-1 strains