Molecular and biological characterization of a non-glycosylated isolate of St Louis encephalitis virus

The glycosylation patterns of the envelope (E) glycoprotein of several naturally occurring strains of St Louis encephalitis (SLE) virus were investigated. SLE viruses were found that contained both glycosylated and non-glycosylated E proteins, and one isolate (Tr 9464) that lacks N-linked glycosylation sites on its E protein was identified. SLE virus monoclonal antibodies that define E protein B cell epitopes and demonstrate biological activities reacted essentially to the same extent with glycosylated and non-glycosylated virions. These results indicate that glycosylation is not essential for epitope conformation or recognition. However, failure to glycosylate the E protein was associated with possible morphogenetic differences as manifested by reduced virus yields and differences in specific infectivity.