Effect of tunicamycin on expression of epitopes on Japanese encephalitis virus glycoprotein E in porcine kidney cells

The effect of tunicamycin (Tm), a glycosylation inhibitor, on the epitopes expressed on Japanese encephalitis virus (JEV) glycoprotein E (gpE) in porc ine kidney stable (PS) cells was studied. At Tm concentration of 2 mug/ml, the virus-infected cells showed markedly reduced or no reactivity with any of the monoclonal antibodies (MAbs) directed against JEV gpE except NHs-2 a nd also with polyclonal antibodies (PAbs) directed against JEV. With the in crease in Tin concentration to 3 mug/ml, a complete loss of the conventiona lly detected reactivity of the MAbs except NHs-2 was recorded while the Pab s showed no decrease in their reactivity. However, the MAb NHs-2 and PAbs l ost their reactivity when the cells treated with 3 mug/ml Tm were stained f or epitopes expressed on their surface indicating that glycosylation plays a role in this phenomenon. Tissue culture fluid (TCF) displayed a low virus content in the presence of 3 mug/ml Tm, indicating probably a down-regulat ion of virus maturation inside the cells. Since preM and NS-1 proteins poss ess besides gpE conserved N-glycosylation sires and play a role in the matu ration of JEV. their expression in nascent, i.e. non-glycosylated form migh t be responsible for the observed low virus content of TCF. Thus, the glyco sylation of JEV gpE seems essential for the acquisition of native conformat ion of its epitopes and their expression in cells.