Detection of cellular cytokine mRNA expression during orf virus infection in sheep: differential interferon-gamma mRNA expression by cells in primary versus reinfection skin lesions. |
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| Authors: | I E Anderson H W Reid P F Nettleton C J McInnes D M Haig |
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| Institution: | Moredun Research Institute, International Research Centre, Pentlands Science Park, Bush Loan, Penicuik, Midlothian EH26 0PZ, UK. |
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| Abstract: | In sheep infected with the parapoxvirus orf virus, primary infection orf skin lesions developed and resolved within 8 weeks. Reinfection lesions were smaller and resolved within 3 weeks. The host response in the skin was characterized by an accumulation of neutrophils, dendritic cells, CD4+ T cells, CD8+ T cells, B cells and T19+ gammadelta T cells. The magnitude of this accumulation paralleled orf virus replication in the skin. In situ hybridization was used to detect cells expressing interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha) and interleukin-4 (IL-4) mRNAs in orf skin. Cells expressing IL-4 mRNA were not detected at any time after infection. Cells expressing IFN-gamma mRNA were detected after reinfection but not after primary infection. Cells expressing TNF-alpha mRNA included epidermal cells, vascular endothelium and uncharacterized cells that increased more rapidly in the skin after reinfection compared to primary infection. The results are consistent with a prominent role for IFN-gamma in the host immune response controlling the severity of the disease. |
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