i Varicella-zoster virus (VZV) is the etiological agent of chickenpox and shingles. Due to the virus's restricted host and cell type tropism and the lack of tools for VZV proteomics, it is one of the least-characterized human herpesviruses. We generated 251 monoclonal antibodies (MAbs) against 59 of the 71 (83%) currently known unique VZV proteins to characterize VZV protein expression in vitro and in situ. Using this new set of MAbs, 44 viral proteins were detected by Western blotting (WB) and indirect immunofluorescence (IF); 13 were detected by WB only, and 2 were detected by IF only. A large proportion of viral proteins was analyzed for the first time in the context of virus infection. Our study revealed the subcellular localization of 46 proteins, 14 of which were analyzed in detail by confocal microscopy. Seven viral proteins were analyzed in time course experiments and showed a cascade-like temporal gene expression pattern similar to those of other herpesviruses. Furthermore, selected MAbs tested positive on human skin lesions by using immunohistochemistry, demonstrating the wide applicability of the MAb collection. Finally, a significant portion of the VZV-specific antibodies reacted with orthologs of simian varicella virus (SVV), thus enabling the systematic analysis of varicella in a nonhuman primate model system. In summary, this study provides insight into the potential function of numerous VZV proteins and novel tools to systematically study VZV and SVV pathogenesis. V aricella-zoster virus (VZV) belongs to the alphaherpesvirus subfamily and is the only member of the genus Varicellovirus that can infect humans (1, 2). Primary infection causes chickenpox and typically occurs in early childhood with a prominent, highly contagious vesicular rash (3). During primary infection, VZV establishes latency in sensory trigeminal and dorsal root ganglia. Reactivation from latency results in a secondary disease called herpes zoster (HZ), or shingles, that is more common in elderly people (4). HZ most frequently occurs in the thoracic or lumbar nerve segments and the distribution area of the trigeminal nerve, causing a painful rash in the corresponding dermatome. While the molecular mechanism for reactivation from latency is not well characterized, it is more frequent in immunocompromised patients (5). The most common sequela of HZ is postherpetic neuralgia (PHN). In addition, VZV reactivation can lead to zoster ophthalmicus, acute retinal necrosis, meningitis, and vasculopathy (6).The seroprevalence of VZV differs significantly between countries, but the majority of individuals are seropositive by the time of adolescence (7). While in otherwise healthy children and adolescents, primary VZV infection mostly resolves spontaneously without sequelae, severe symptoms may occur in immunocompromised people and during pregnancy (6). Vertical transmission of VZV during the first trimester causes congenital varicella syndrome (CVS), which is characterized by skin lesions, hypoplasia, low birth weight, and neurological dis...