MULTIPLE ANTI-CYTOKINE ACTIVITIES SECRETED FROM TANAPOX VIRUS-INFECTED CELLS

Tanapox virus (TPV) produces a mild disease in humans characterized by transient fever, one or more nodular skin lesions and regional lympha denopathy. We demonstrate that TPV-infected cells, but not mock-infect ed cells, secrete an early 38 kDa glycopeptide that, unlike any other known protein, binds to human (h) interferon-gamma, hIL-2 and HIL-5. I n concomitant experiments this polypeptide failed to bind to hIL-I alp ha, hIL-3, hIL-4, hIL-6, hIL-7, hIL-8 or hIL-10. Inhibition of hIL-2 a nd hIL-5 biological activities were demonstrated using a hIL-2-depende nt mouse T cell line (HT-2) and a hIL-5-dependent erythroleukemia cell line (TF-1), respectively. The 38 kDa polypeptide also inhibited the bioactivity of interferon-gamma. Taken together, our results suggest t hat TPV has evolved multiple pathways to disarm both T(H)1 cell-mediat ed (IL-2 and interferon-gamma) and T(H)2-associated (IL-5) immune resp onses for its infectivity with remarkable genetic economy.