Stable secretion of a soluble, oligomeric form of rabies virus glycoprotein: influence of N-glycan processing on secretion.

Rabies virus glycoprotein (RGP) is a 505 amino acid type I transmembrane glycoprotein that is important in the pathogenesis of rabies virus infection. RGP also stimulates the development of neutralizing antibodies by the host. N-linked glycosylation is required for both cell surface expression and immunogenicity of RGP. In the current study, a soluble form of RGP, constructed by insertion of a stop codon external to the transmembrane domain, was expressed in transfected Chinese hamster ovary cells. The soluble form of RGP was found to be appropriately antigenic and immunogenic. Similar to full-length RGP, the soluble form was assembled into homodimers and homotrimers. Core glycosylation was required for secretion of soluble RGP and cell surface expression of full-length RGP. In addition, initial glucose trimming of the N-glycans was necessary and sufficient for secretion of soluble RGP and cell surface expression of full-length RGP. Further N-glycan processing was not required for secretion or cell surface expression of soluble or full-length RGP, respectively.