Lectins Inhibit the Aujeszky's Disease Virus-Induced Interferon-α Production of Porcine Peripheral Blood Mononuclear Cells

Abstract

The interaction between virus and peripheral blood mononuclear cells (PBMC) required to elicit the production of interferon-α (IFN-α) by the so-called natural interferon-producing cell is unknown. However, results from inhibition experiments suggest that viral glycoproteins are essential in this IFN induction process. We demonstrate here that cellular glycoproteins also appear to be involved in the initiation of IFN-α production. Lectins, that is, sugar binding glycoproteins, inhibited the Aujeszky's disease virus-induced IFN-α production of porcine PBMC by up to 99%. The level of inhibition varied with the lectin used (concanavalin A, Galanthus nivalis lectin, Helix pomatia lectin, and lentil lectin). Preincubation experiments with porcine cells and concanavalin A (ConA) revealed that the lectin exerted its major effect directly on the PBMC. Although the IFN-α production in some cases was reduced by more than 90%, the PBMC were still able to proliferate in response to mitogenic lectins. The ConA-mediated inhibition of the IFN-α production was reduced if the lectin was added later than 6-8 h after the start of induction and was not mediated by soluble factors. Both orthovanadate and staurosporine inhibited the IFN-α production and did not relieve the ConA-mediated inhibition. Thus, ConA seems to interfere with the early events during IFN-α induction, but the mechanisms behind this interference could not be clarified.