Intracellular transport of varicella-zoster glycoproteins

Previous observations have established that varicella-zoster virus (VZV) is enveloped in the trans-Golgi network (TGN) in cultures infected with VZV and that the glycoprotein gE is targeted to the TGN by a signal sequence (AYRV) and an acidic TGN signal patch in its cytosolic domain. Neither sequence is present in other VZV glycoproteins. Like gE, gI was targeted to the TGN when it was expressed in transfected cells, suggesting that gI also contains TGN targeting information (colocalized with gE and the AP-1 adaptin complex). In contrast, gB, gC, gH, and gL immunoreactivities were not detected in the TGN when they were expressed individually in transfected cells. In VZV-infected cells, gE, gI, gH, and gL were all concentrated in the TGN. Since VZV glycoproteins that lack targeting sequences (gB, gC, gH, and gL) concentrated in the TGN of infected cells, it is proposed that gE and gI, which have such sequences, serve as navigator glycoproteins, forming complexes that direct the signal-deficient glycoproteins to the TGN.