Mareks disease is among the most common viral diseases of poultry affecting chicken flocks worldwide. recognized the tegument protein VP22 (pUL49) as a major MDV-encoded cell cycle regulator, as its vector-driven overexpression in cells lead to a dramatic cell cycle arrest in S-phase. This impressive practical feature of VP22 appears to depend on its ability to associate with histones in the nucleus. Finally, we founded that VP22 manifestation causes the induction of massive and severe DNA damages in cells, which might cause the observed intra S-phase arrest. Taken together, our results provide the first evidence for a hitherto unknown function of the VP22 tegument protein in herpesviral reprogramming of the cell cycle of the host cell and its potential implication in the generation of DNA damages. Introduction Gallid herpesvirus 2 (GaHV-2), more frequently referred to as Mareks disease virus (MDV), is an alphaherpesvirus (type species of the genus Mardivirus) and the causative agent of a highly infectious lymphoproliferative disease termed Mareks disease (MD) affecting many birds in the family. Despite global vaccination campaigns that are effective to prevent disease development, MDV field strains continue to spread in poultry and appear to evolve towards increased virulence. The dissemination of MDV in poultry is mediated by infectious viral particles associated with dander and feather debris [1], [2]. With the exception of the feather follicle epithelium, the site where free infectious viral particles are shed, the virus remains strictly cell-associated and progression of the infection is restricted to viral cell-to cell spread [3]. The MDV particle is composed of a 180-kbp double-strand DNA genome packaged in an icosaedric capsid surrounded by a tegument layer, which insures the morphological and functional continuity between the capsid and the host cell derived viral envelope. By homology with other alphaherpesviruses, a number of viral proteins composing the tegument have been identified, including a major tegument protein, VP22 (pUL49), various trans-activators and two protein kinases (pUL13 and pUS3). The UL49-encoded VP22 protein is abundantly expressed in infected cells and is essential for MDV replication [4], [5], [6]. VP22 is a specific tegument protein of alphaherpesviruses and conserved among this subfamily. To date, the absolute requirement of the UL49 gene for viral replication was initially demonstrated for MDV [5] and afterwards for Varicella Zoster virus (VZV) [7]. The deletion of VP22 in other alphaherpesviruses including Herpes Simplex virus 1 (HSV-1), Pseudorabies disease (PRV), Bovine herpesvirus 1 (BoV-1) still enables viral replication, though viral spread can be low in some cell types [8] actually, [9], [10], [11], [12]. While its part in disease infection continues to be unclear, it had been Nalmefene hydrochloride proven for HSV-1 that VP22 interacts with and recruits different viral protein, like the trans-activators ICP0, ICP4 and viral glycoproteins composing the infectious virions [9], [10], [13]. Furthermore, VP22 was proven to interact with mobile protein mixed up in corporation of microtubules and nucleosome set up [14], [15]. The VP22 proteins encoded by MDV stocks common practical features with VP22 encoded by additional alphaherpesviruses [5], [16]. It had been previously demonstrated that MDV-VP22 displays both a cytoplasmic and nuclear area in contaminated cells and accumulates in the nucleus upon overexpression in cells [4]. Furthermore, MDV-VP22 exhibits a solid affinity to DNA, heterochromatin especially, also to microtubules [4], [17]. We proven the part of VP22 in MDV cell-to-cell spread previously, which could clarify the need of VP22 in MDV replication [16], [18]. It had Nalmefene hydrochloride been recently demonstrated that recombinant MDV infections expressing VP22 having a C or N-terminal GFP-tag are extremely attenuated recommending that VP22 might Mouse monoclonal to CK4. Reacts exclusively with cytokeratin 4 which is present in noncornifying squamous epithelium, including cornea and transitional epithelium. Cells in certain ciliated pseudostratified epithelia and ductal epithelia of various exocrine glands are also positive. Normally keratin 4 is not present in the layers of the epidermis, but should be detectable in glandular tissue of the skin ,sweat glands). Skin epidermis contains mainly cytokeratins 14 and 19 ,in the basal layer) and cytokeratin 1 and 10 in the cornifying layers. Cytokeratin 4 has a molecular weight of approximately 59 kDa. are likely involved in MDV-induced lymphomagenesis [6], [19]. Nevertheless, the complete role of VP22 in MDV MD and replication pathogenesis remains unclear. Notably, the practical need for the VP22 Nalmefene hydrochloride nuclear distribution can be unfamiliar still, actually if previous reviews on VP22 encoded Nalmefene hydrochloride by alphaherpesviruses evoke a feasible regulatory function of VP22 within nuclei [17], [20], [21], [22]. Disease infection frequently leads to the disruption of key mobile processes inside the Nalmefene hydrochloride sponsor cell. The subversion of cell routine pathways is a well-established mechanism by which viruses create the most suitable environment for their replication. Especially, the induction of S-phase is either mandatory or at least advantageous for lytic replication of a number of viruses. The eminent role of cellular factors from the DNA synthesis machinery in viral replication was demonstrated for viruses from different families such as the Flaviviridae, Retroviridae, Parvoviridae, and Polyomaviridae [23], [24], [25], [26], [27], [28]. In contrast, herpesviruses encode their own DNA polymerase and accessory proteins, and thus theoretically do not require an S-phase environment to support their replication (reviewed in [29], [30]). Nevertheless, several studies have demonstrated the importance of the S-phase in the life cycle.