CYTOKINE REGULATION BY VIRUS-INFECTION - BOVINE VIRAL DIARRHEA VIRUS,A FLAVIVIRUS, DOWN-REGULATES PRODUCTION OF TUMOR-NECROSIS-FACTOR-ALPHA IN MACROPHAGES IN-VITRO

Bovine bone marrow-derived mascrophages were infected in vitro with no ncytopathic or cytopathic strains of bovine viral diarrhea virus. Infe ction with both biotypes resulted in a decreased production of tumor n ecrosis factor alpha upon stimulation with heat-inactivated Salmonella dublin or lipopolysaccharide. Other macrophage functions were not dow nregulated,indicating that the observed effect was not due to a loss i n macrophage viability. The downregulated production of tumor necrosis factor alpha in infected macrophages may contribute to the well-docum ented immunosuppression in animals infected with bovine viral diarrhea virus.