Membrane association and secretion of the Japanese encephalitis virus NS1 protein from cells expressing NS1 cDNA

The biosynthesis of the flavivirus nonstructural glycoprotein, NS1, has important implications for (1) vaccine production, since NS1 immunity can protect animals from flavivirus infection; and (2) virion maturation, since NS1 is coretained with immature forms of the structural glycoprotein E in the endoplasmic reticulum (ER) of infected cells. To examine the molecular basis for NS1 retention within the ER we have expressed fragments of Japanese encephalitis virus (JEV) cDNA encoding NS1 in BHK cells. These transient expression studies showed that the JEV NS1 protein was faithfully processed when expressed in isolation, and have revealed that NS1 expressed in the absence of any other viral genes behaves like the NS1 protein found in JEV-infected cells with respect to retention in the ER, secretion, glycosylation, membrane association, and dimerization.