The endoplasmic reticulum-associated VP7 of rotavirus is targeted to axons and dendrites in polarized neurons

Rotavirus, which matures and is retained in the endoplasmic reticulum, was used to examine how polarized dorsal root ganglion and spinal cord neurons distributed cytoplasmic and endoplasmic reticulum-associated proteins. A remarkable observation was that NS28, a trans-endoplasmic reticulum-membrane protein which functions as a receptor for budding particles, remained in the cell body during the whole course of infection (48 h) while the VP7 glycoprotein, which is endoplasmic reticulum associated and usually retained in the endoplasmic reticulum, was targeted to axons already 4 h post infection. VP7 was furthermore transported in an endo-beta-N-acetylglucosaminidase H sensitive form through the secretory pathway. The segregated appearances of NS28 and the endo-beta-N-acetylglucosaminidase H sensitive VP7 indicate that VP7 enters a transport compartment separate from NS28. Brefeldin A treatment rapidly disintegrated the Golgi apparatus of the neurons and rapidly blocked axonal transport of Sendai virus glycoproteins, while axonal transport of rotavirus VP7 was not blocked, suggesting that VP7 uses an intracellular pathway in neurons which does not involve the Golgi apparatus.