The
rabies virus glycoprotein (G protein) has several important functions and is a major antigenic stimulus of the host immune system following rabies virus
infection or vaccination. We developed a model system for studying the role of N-linked glycosylation in the intracellular transport and antigenicity of this molecule. The full-length
cDNA of the
G protein of the ERA strain of rabies virus was inserted into the eukaryotic shuttle vector pSG5 and then stably transfected into wild-type Chinese hamster ovary (CHO) cells and mutant CHO cell lines defective in glycosylation. Transfected wild-type CHO cells expressed the
G protein (detected by immunofluorescence) on the cell surface in a manner similar to rabies virus-infected cells. The transfected wild-type CHO cells were shown by immunoprecipitation to produce a
protein of 67K that comigrated with the fully glycosylated
G protein isolated from virus-infected cells or purified virions. Treatment of the transfected cell lines with
tunicamycin completely blocked surface expression and resulted in the intracellular accumulation of the
G protein, suggesting that the presence of N-linked
oligosaccharides is important for transport of this
glycoprotein to the plasma membrane. The
G protein cDNA was also expressed in the
lectin-resistant CHO cell lines Lec 1, Lec 2 and Lec 8. In these cells initial N-linked glycosylation does occur, but later steps in processing of the
oligosaccharides are blocked. In each case, the
G protein was expressed on the surface of
lectin-resistant CHO cells in a similar manner to expression on wild-type CHO cells. This suggests that various different N-linked
oligosaccharide structures support intracellular transport of this
glycoprotein. Thus, stably transfected CHO cell lines will provide a useful model system for further studies of the role of N-linked glycosylation in trafficking and antigenicity of the rabies virus
G protein.