Bluetongue virus (BTV) is a vector-borne, nonenveloped icosahedral particle that is organized in two capsids, an outer capsid of two proteins, VP2 and VP5, and an inner capsid (or core) composed of two major proteins, VP7 and VP3, in two layers. The VP3 layer (subcore) encloses viral transcription complex (VP1 polymerase, VP4 capping enzyme, VP6 helicase) and a 10-segmented double-stranded (dsRNA) genome. Although much is known about the BTV capsids, the order of the core assembly and the mechanism of genome packaging remain unclear. Here, we established a cell-free system to reconstitute subcore and core structures with the proteins and ssRNAs, demonstrating that reconstituted cores are infectious in insect cells. Furthermore, we showed that the BTV ssRNAs are essential to drive the assembly reaction and that there is a distinct order of internal protein recruitment during the assembly process. The in vitro engineering of infectious BTV cores is unique for any member of the Reoviridae and will facilitate future studies of RNA-protein interactions during BTV core assembly.assembly pathway | Orbivirus | engineered particle

Translation initiation of hepatitis C virus (HCV) occurs through an internal ribosome entry site (IRES) located at its 5′‐end. As a positive‐stranded RNA virus, HCV uses its genome as a common template for translation and replication, but the coordination between these two processes remains poorly characterized. Moreover, although genetic evidence of RNA–protein interactions for viral replication is accumulating because of subgenomic replicons and a recent culture system for HCV, such interactions are still contentious in the regulation of translation. To gain insight into such mechanisms, we addressed the involvement of cis and trans viral factors in HCV IRES activity by using a cell‐based RNA reporter system. We found that the HCV 3′ noncoding region (NCR) strongly stimulates IRES efficiency in cis, depending on the genotype and the cell line. Moreover, we confirmed the role of the core protein in viral gene expression as previously reported in vitro. Surprisingly, we observed a similar effect, i.e. a twofold increase under low amounts of NS5B RNA polymerase, followed by a decrease at higher concentrations. However, no contribution of NS5A to HCV IRES‐mediated translation was noted and no cooperative effect could be detected between 3′ NCR and viral proteins or between proteins. Collectively, these results suggest that HCV RNA translation is regulated, and that the switch from translation to replication might involve a sequential requirement for both cis and trans viral factors, because of their apparent lack of synergy, probably with the aid of host factors.

Seven nucleotide changes characteristic of the hepatitis C virus genotype 3 59 untranslated region: correlation with reduced in vitro replication Computer analysis of 158 hepatitis C virus (HCV) 59 untranslated region (59 UTR) sequences from the six genotypes showed that the 59 UTR from genotype 3 displays seven specific non-contiguous nucleotide changes, at positions 8, 13, 14, 70, 97, 203 and 224. The purpose of this study was to investigate the impact of these changes on translation and replication activities. Indeed, these modifications could alter both the internal ribosome entry site (IRES) present in the 59 UTR of the plus-strand RNA and the 39 end of the minus strand involved in the initiation of plus-strand RNA synthesis. We found that the genotype 3-specific nucleotide changes do not modify the in vitro or ex vivo translation activity of the corresponding IRES, in comparison with that of genotype 1. In contrast, in vitro replication from the minus-strand RNA is eight times less efficient for genotype 3 than for genotype 1 RNA, suggesting the involvement of some nucleotide changes in the reduction of RNA synthesis. Nucleotides 13, 14 and 224 were found to be responsible for this effect. Moreover, a reduced replicative activity was confirmed ex vivo for genotype 3, but to a lesser extent than that observed in vitro, using an RNA minigenome. INTRODUCTIONHepatitis C virus (HCV) affects nearly 200 million people worldwide. Five to seven per cent of patients die as a consequence of liver disease. Hepatic steatosis is a common feature of liver biopsy specimens from patients with chronic hepatitis C, and its presence is associated with fibrotic progression (Rubbia-Brandt et al., 2000). Numerous factors including gender, age of infection, alcohol consumption, exposure to other hepatotoxins and perturbation of lipid metabolism have been identified as determinants of pathogenesis. Viral factors may also be critical determinants of steatosis in chronic hepatitis C, particularly HCV genotype (Rubbia-Brandt et al., 2004). Genetic variability of the RNA genome has made it possible to distinguish six HCV genotypes and over 70 subtypes (Simmonds et al., 2005). Each of these genotypes displays particular features such as resistance to interferon/ribavirin treatments. Thus, genotype 1-infected patients respond less efficiently to therapy than those infected with genotype 2 and 3 viruses. Conversely, patients with HCV genotype 3 infection and chronic hepatitis C are more likely to be subjected to a liver steatosis than those infected with HCV genotype 1 (Lonardo et al., 2006). Viral determinants of this differential progression are as yet poorly understood. It has been suspected that sequence variations in the envelope E1 and E2 glycoproteins might be involved in differences in pathogenesis between genotypes 1 and 3 (Shaw et al., 2003). More recently, in vitro models suggested involvement of the core protein as a viral factor associated with lipid accumulation in genotype 3 infection (Abid et al., 2005;Hourioux et al., 20...

Neutrophilic dermatosis of the dorsal hands, a localized form of Sweet's syndrome, was recently described, and can be associated with several diseases including infections. Chronic hepatitis C virus infection has been proposed as a possible triggering factor. The authors present a case in which the clinical and laboratory workup diagnosis only revealed positive serology for hepatitis C virus. Although a cause-effect relation could not be proved, it might be advisable to include serology for this virus in the initial evaluation of patients with neutrophilic dermatosis.