Cytokine transcription in lymph nodes of cattle in different stages of bovine leukemia virus infection

Bovine leukemia virus (BLV) is a transforming oncovirus that contains no oncogenes or preferred site of proviral integration. The role of cytokines in the disease process of BLV is potentially important due to the similarity of BLV with other retroviruses in which cytokines play a role, such as HTLV-I and -II. Mesenteric and supra-mammary lymph nodes were obtained from a panel of nine cattle. Three were non-infected controls, three were BLV-positive aleukemic (AL), and three were BLV-positive persistent lymphocytotic (PL). Mononuclear cells were perfused from the organs and total RNA extracted from either 1 × 108 unseparated cells or 1 × 107 purified CD4CD8 T-cells. cDNA was generated and subjected to RT-PCR to analyze cytokine transcription during disease progression. cDNA levels were normalized using β-actin PCR at sub-plateau cycle number, enabling a semi-quantitative assessment of cytokine gene transcripts. Using this approach, IL-2, IL-10 and IFN-γ message was detected in the T-cell fractions of all of the BLV-infected animals, but not in the non-infected controls.