Despite the physical distance between the domestic pigs

Despite the physical distance between the domestic pigs and the populations of other animals in this study, neutralizing antibody against WBRV1 was detected in a domestic pig serum. In Japan, wild boars represent a constant threat for introducing the viruses, such as Aujeszky’s disease virus, into the commercial swine industry (Mahmoud et al., 2011). Therefore, wild boars may play a role in transmission WBRV1 into swine population in Japan and WBRV1 may have already infiltrated Japanese pig farms. However, the prevalence of WBRV1 in swine population in Japan should not be estimated by only serological data. Further studies are needed to clarify the prevalence of this virus in pigs. In this study, we did not investigate how WBRV1 infects animals. Thus, understanding of the prevalence of this virus in not only pigs but also other animals and insects and exploration of its life cycle needs additional investigations.

Conflict of interest


The Alloherpesviridae is a new virus family in the Herpesvirales order. It is comprised of both piscine and amphibian herpesviruses (McGeoch et al., 2006) and is evolutionary distinct from the other families of the order Herpesvirales (Davison et al., 2009; Hanson et al., 2011; Waltzek et al., 2009). Members of the Alloherpesviridae family are increasingly recognised as pathogens in aquaculture. One important pathogen is the Cyprinid herpesvirus 3 (CyHV-3), a herpesvirus from the Cyprinivirus genus which infects common carp, Cyprinus carpio and its coloured variety, the koi (Waltzek et al., 2009). CyHV-3 infections may cause severe outbreaks of the so called koi herpesvirus disease (KHVD) leading to up to 100% mortalities in infected populations, consequently causing a severe negative impact on carp aquaculture and the ornamental koi trade.
Characteristic features of the virus include a large 295kbp long linear genome with 156 potential ORFs (Aoki et al., 2007) encoding for at least 40 proteins building the mature viron (Michel et al., 2010). The CyHV-3 virion has an icosahedral capsid, an amorphic protein tegument and a lipid envelope containing virus glycoproteins (Dishon et al., 2005; Hutoran et al., 2005) which it acquires during the lxr agonists step from infected cells. This process is similar to the mechanism observed for mammalian herpesviruses (Mettenleiter, 2002). In electron microscopical studies on infected cells, CyHV-3 nucleocapsids appear to bud from the inner nuclear membrane into the perinuclear space. When the nucleocapsids cross the outer nuclear membrane into the cytoplasm, its primary envelope is lost and a second envelope is acquired through budding into cytoplasmic vesicles (Hanson et al., 2011; Miwa et al., 2007).
In enveloped viruses, the viral membrane is required for the critical steps of entry into the target cell and fusion with the host’s cellular membrane in order to deliver the viral capsid into the cell cytosol. The classical endocytotic pathway, which many viruses use as the primary step of internalisation, is clathrin-dependent endocytosis (Marsh and Helenius, 2006). Instead, many viruses use the lipid raft/caveola-dependent entry route, which is characterised by the importance of high levels of cholesterol and sphingolipids ((Doherty and McMahon, 2009) and references therein). In the plasma membrane of cells (chole) sterol–sphingolipids are particularly enriched in dynamic nanoscale liquid ordered microdomains, ordered assemblies of proteins and lipids, which are also termed as lipid rafts (Simons and Toomre, 2000). These microdomains are associated with a range of important cellular and physiological functions including cell signalling, membrane and protein trafficking and sorting and nutrient transport. Lipid rafts have been extensively studied in mammals. In fish, lipid rafts have been isolated from rainbow trout (Zehmer and Hazel, 2003), Atlantic cod (Gylfason and Asgeirsson, 2008), and common carp (Brogden et al., 2014), furthermore the presence of functional lipid rafts in goldfish macrophages was shown (Garcia-Garcia et al., 2012). The lipid raft model is used to investigate a large range of processes including, protein trafficking (Ikonen, 2001), metabolic diseases (Maalouf et al., 2010) and cell signalling (Magee et al., 2002; Varma and Mayor, 1998). In addition, lipid rafts and cell membrane cholesterol were found to be involved in various stages of the viral life cycle, such as entry (Nguyen and Hildreth, 2000; Ono and Freed, 2001), assembly and budding (Chazal and Gerlier, 2003). Many studies demonstrated that several enveloped viruses enter host cells in a cholesterol-dependent manner, including coronavirus (Choi et al., 2005), poxvirus (Chung et al., 2005), paramyxovirus (Martin et al., 2012) and herpesvirus (Bender et al., 2003).