Recombinant expression of the TGEV membrane glycoprotein M.

We have previously shown that the membrane protein M of TGEV is involved in efficient induction of alpha interferon (IFN alpha) synthesis by non-immune peripheral blood mononuclear cells incubated with fixed, TGEV-infected cells or inactivated virions. In order to determine whether M protein is able to induce interferon in the absence of other viral factors, we expressed the protein either stably in the porcine ST cells or transiently in the simian COS7 cells. Although showing no obvious difference in intracellular localization or glycosylation compared to its viral counterpart, the recombinant molecule failed to induce significant IFN activity.