Herpes simplex virus (HSV) glycoprotein H is partially processed in a cell line that expresses the glycoprotein and fully processed in cells infected with deletion or ts mutants in the known HSV glycoproteins.
Cell lines that constitutively express herpes simplex virus 1 (HSV-1) glycoprotein H (gH-1) failed to synthesize the mature form of gH and accumulated a precursor-like form of the glycoprotein, which was retained intracellularly, most likely in RER. Fine-structure analysis of the oligosaccharides present in recombinant gH revealed oligosaccharides processed by RER enzymes; sialylated complex-type and biantennary oligosaccharides, which are assembled in the trans-Golgi, were absent. A small fraction had the characteristics of oligosaccharides processed by the early mannosidases of the Golgi. These findings suggest that a defect in the transport out of RER to the Golgi may account for the intracellular retention of the immature form of gH in cells that express the glycoprotein constitutively. Upon superinfection of cells expressing gH-1 with HSV-2, recombinant gH-1 underwent maturation, indicating that a viral function is required to attain full processing of gH. The known HSV glycoproteins do not appear to carry out this function, since in cells infected with deletion mutants in gD, gG, gE, and gE-gI, with a spontaneous gC- mutant, or with a temperature-sensitive mutant in gB, maturation of gH occurred independently of the presence or of the maturation of the single glycoproteins tested. The present findings together with previous observations on HSV, human CMV, and the EBV homologue of gH suggest that inability of gH to undergo full processing in the absence of viral protein(s) is a property of gH.
Foà-Tomasi
L
L
Section on Microbiology and Virology, University of Bologna, Italy.
Avitabile
E
E
Boscaro
A
A
Brandimarti
R
R
Gualandri
R
R
Manservigi
R
R
Dall'Olio
F
F
Serafini-Cessi
F
F
Fiume
G C
GC
D000818:Animals; D002460:Cell Line; D002872:Chromosome Deletion; D005814:Genes, Viral; D008358:Mannose / Q000378:metabolism; D009154:Mutation; D009844:Oligosaccharides / Q000302:isolation & purification; D010957:Plasmids; D011499:Protein Processing, Post-Translational; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification; D011995:Recombination, Genetic; D015183:Restriction Mapping; D018139:Simplexvirus / Q000235:genetics*; D014709:Vero Cells; D014759:Viral Envelope Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000302:isolation & purification
D009844:Oligosaccharides; D011994:Recombinant Proteins; D014759:Viral Envelope Proteins; C044200:glycoprotein H, herpes simplex virus type 1; D008358:Mannose