Progeny Varicella-Zoster Virus Capsids Exit the Nucleus but Never Undergo Secondary Envelopment during Autophagic Flux Inhibition by Bafilomycin A1

Girsch, James H.; Walters, Katherine; Jackson, Wallen; Grose, Charles

One of the initial methods used to detect autophagy was microscopy (4) . The autophagosome is characterized by its double-walled outer membrane containing microtubule-associated protein 1 light chain 3B (LC3-II), the lipidated form of LC3-I (5) . Because of the diameter of the autophagosome (300 to 1,000 nm) and its immunogenic LC3-II protein, confocal microscopy with a fluorescent-antibody probe is an excellent method by which to visualize and enumerate autophagosomes in VZV-infected cells (6) . Using this technology, we documented an abundant autophagy response in the skin vesicles within the exanthem of human subjects with herpes zoster (7) . We have reproduced these results both in infected cell cultures and in infected human skin xenografts within the severe combined immunodeficient (SCID) mouse model for varicella (8, 9) . More recently, these results have been duplicated in a human skin organ culture model for herpes zoster infection (10) . In another set of experiments, we documented autophagic flux in VZV-infected cells (9) . In other words, the accumulation of autophagosomes was not caused by a block in the autophagy pathway. These VZV data are supported by papers that report similar autophagy results after infection with the closely related alphaherpesvirus pseudorabies virus (PRV), as well as duck enteritis herpesvirus (11, 12) , both of which also lack the herpesvirus ICP34.5 homolog.