Transforming growth factor beta production during rat cytomegalovirus infection

BL Haagmans, KJ Teerds, AJ van den Eijnden-van Raaij, MC Horzinek and VE Schijns Department of Infectious Diseases and Immunology, Veterinary Faculty, Utrecht University, The Netherlands. Haagmans@vetmic.dgk.ruu.nl We analysed the production of transforming growth factor beta (TGF- beta) during a cytomegalovirus (CMV) infection in a rat model system. Splenocytes from immunocompetent rats infected with rat CMV (RCMV) released increased amounts of TGF-beta1. TGF-beta production was also evident in RCMV-infected radiation-immunosuppressed rats; their sera inhibited the interleukin 2-induced proliferation of T cells, which could be restored by anti-TGF-beta antibodies. In addition, TGF-beta production could be visualized immunohistologically in the lungs, spleen, liver and bone marrow of radiation-immunosuppressed infected rats. The virus directly induced this cytokine since TGF-beta was produced upon RCMV infection in vitro. The induction of TGF-beta production may contribute to immunosuppression during CMV infection.