MDV glycoprotein D is expressed in the feather follicle epithelium of infected chickens

Glycoprotein D (gD) and its homologues are essential for many alphaherpesvirus life cycles. A gene encoding a homologue of gD was recently found in the Marek's disease virus (MDV) genome. Interestingly, gD-negative MDV mutants apparently replicate unimpaired in both cell culture and chickens. In this study, we show the expression of the gD homologue of MDV in feather follicle epithelium in infected birds. The gD homologue was detected in a few feather follicles even when most of the follicles were expressing pp38 or gB, other MDV-specific proteins. These observations indicate that the MDV gD homologue is expressed in a very limited set of cells and may be differently regulated. Since feather follicle epithelium of infected birds are the only place where the infectious cell-free MDV virions can be recovered, analysis of the transcriptional regulation of gD may lead to the understanding of the cell-associated nature of MDV.