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.

Abstract

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.

• Authors: Shyrley P Amarilla, Jaime Gómez-Laguna, Librado Carrasco, Irene M Rodríguez-Gómez, José M Caridad Y Ocerín, Sophie B Morgan, Simon P Graham, Jean-Pierre Frossard, Trevor W Drew, Francisco J Salguero
• Journal: Veterinary immunology and immunopathology (Vet Immunol Immunopathol) Vol. 164 Issue 3-4 Pg. 137-47 (Apr 15 2015) ISSN: 1873-2534 [Electronic] Netherlands
• PMID: 25739319 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

Chemical References

• Antigens, Viral
• Cytokines
• Interleukin-1alpha

Topics

• Animals
• Antigens, Viral (blood)
• Cytokines (biosynthesis)
• Interleukin-1alpha (biosynthesis)
• Lung (immunology, pathology)
• Porcine Reproductive and Respiratory Syndrome (immunology)
• Porcine respiratory and reproductive syndrome virus (immunology)
• Swine
• Up-Regulation