Differential Levels of mRNAs for Cytokines, the Interleukin-2 Receptor and Class II DR/DQ Genes in Ovine Interstitial Pneumonia Induced by Maedi Visna Virus Infection

Abstract

The relative levels of selected cytokine, interleukin-2 receptor, class II DR and DQ RNAs, and maedi visna virus (MVV) RNA were measured by reverse-transcriptase polymerase chain reaction (RT-PCR) in the lungs of sheep with natural maedi visna virus infection ( n = 8) and a group of age/sex/breed-matched MVV seronegative sheep ( n = 4). These animals were divided into two groups, irrespective of serostatus, according to the severity of lymphocytic interstitial pneumonia. The severity of lung lesions was determined by clinical sign, lung weight, and lesion score in the lungs measured by three pathologic parameters. Sheep with lung lesions showed hyperelevated levels of granulocyte-macrophage colony-stimulating factor upregulated γ-interferon, interleukin 2 receptor, and interleukins 1β, 4, and 10 mRNAs. Class II mRNAs were found not to be elevated in the lungs of sheep with lung lesions. Tumor necrosis factor α and transforming growth factor β1 mRNA levels were similar in all sheep lungs studied. We discuss the major roles played by granulocyte-macrophage colony-stimulating factor and type 2 cytokines in the pathogenesis of this disease and the possible stimulation of the production of these cytokines by viral surface glycoproteins.