Hepatitis C virus (HCV) is among the most relevant causes of liver cirrhosis and hepatocellular carcinoma. Research is complicated by a lack of accessible small animal models. The systematic investigation of viruses of small mammals could guide efforts to establish such models, while providing insight into viral evolutionary biology. We have assembled the so-far largest collection of small-mammal samples from around the world, qualified to be screened for bloodborne viruses, including sera and organs from 4,770 rodents (41 species); and sera from 2,939 bats (51 species). Three highly divergent rodent hepacivirus clades were detected in 27 (1.8%) of 1,465 European bank voles (Myodes glareolus) and 10 (1.9%) of 518 South African four-striped mice (Rhabdomys pumilio). Bats showed anti-HCV immunoblot reactivities but no virus detection, although the genetic relatedness suggested by the serologic results should have enabled RNA detection using the broadly reactive PCR assays developed for this study. 210 horses and 858 cats and dogs were tested, yielding further horse-associated hepaciviruses but none in dogs or cats. The rodent viruses were equidistant to HCV, exceeding by far the diversity of HCV and the canine/equine hepaciviruses taken together. Five full genomes were sequenced, representing all viral lineages. Salient genome features and distance criteria supported classification of all viruses as hepaciviruses. Quantitative RT-PCR, RNA in-situ hybridisation, and histopathology suggested hepatic tropism with liver inflammation resembling hepatitis C. Recombinant serology for two distinct hepacivirus lineages in 97 bank voles identified seroprevalence rates of 8.3 and 12.4%, respectively. Antibodies in bank vole sera neither cross-reacted with HCV, nor the heterologous bank vole hepacivirus. Co-occurrence of RNA and antibodies was found in 3 of 57 PCR-positive bank vole sera (5.3%). Our data enable new hypotheses regarding HCV evolution and encourage efforts to develop rodent surrogate models for HCV.

Formation of iron/sulfur (Fe/S) clusters, protein translocation and protein folding are essential processes in the mitochondria of Saccharomyces cerevisiae. In a systematic approach to characterize essential proteins involved in these processes, we identified a novel essential protein of the mitochondrial matrix, which is highly conserved from yeast to human and which we termed Isd11. Depletion of Isd11 caused a strong reduction in the levels of the Fe/S proteins aconitase and the Rieske protein, and a massive decrease in the enzymatic activities of aconitase and succinate dehydrogenase. Incorporation of iron into the Fe/S protein Leu1 and formation of the Fe/S cluster containing holoform of the mitochondrial ferredoxin Yah1 were inhibited in the absence of Isd11. This strongly suggests that Isd11 is required for the assembly of Fe/S proteins. We show that Isd11 forms a stable complex with Nfs1, the cysteine desulfurase of the mitochondrial machinery for Fe/S cluster assembly. In the absence of Isd11, Nfs1 is prone to aggregation. We propose that Isd11 acts together with Nfs1 in an early step in the biogenesis of Fe/S proteins.

Hepatitis E virus (HEV) is one of the most common causes of acute hepatitis in tropical and temperate climates. Tropical genotypes 1 and 2 are associated with food-borne and waterborne transmission. Zoonotic reservoirs (mainly pigs, wild boar, and deer) are considered for genotypes 3 and 4, which exist in temperate climates. In view of the association of several zoonotic viruses with bats, we analyzed 3,869 bat specimens from 85 different species and from five continents for hepevirus RNA. HEVs were detected in African, Central American, and European bats, forming a novel phylogenetic clade in the family Hepeviridae . Bat hepeviruses were highly diversified and comparable to human HEV in sequence variation. No evidence for the transmission of bat hepeviruses to humans was found in over 90,000 human blood donations and individual patient sera. Full-genome analysis of one representative virus confirmed formal classification within the family Hepeviridae . Sequence- and distance-based taxonomic evaluations suggested that bat hepeviruses constitute a distinct genus within the family Hepeviridae and that at least three other genera comprising human, rodent, and avian hepeviruses can be designated. This may imply that hepeviruses invaded mammalian hosts nonrecently and underwent speciation according to their host restrictions. Human HEV-related viruses in farmed and peridomestic animals might represent secondary acquisitions of human viruses, rather than animal precursors causally involved in the evolution of human HEV.

The hepatitis B virus (HBV), family Hepadnaviridae, is one of most relevant human pathogens. HBV origins are enigmatic, and no zoonotic reservoirs are known. Here, we screened 3,080 specimens from 54 bat species representing 11 bat families for hepadnaviral DNA. Ten specimens (0.3%) from Panama and Gabon yielded unique hepadnaviruses in coancestral relation to HBV. Full genome sequencing allowed classification as three putative orthohepadnavirus species based on genome lengths (3,149-3,377 nt), presence of middle HBV surface and X-protein genes, and sequence distance criteria. Hepatic tropism in bats was shown by quantitative PCR and in situ hybridization. Infected livers showed histopathologic changes compatible with hepatitis. Human hepatocytes transfected with all three bat viruses cross-reacted with sera against the HBV core protein, concordant with the phylogenetic relatedness of these hepadnaviruses and HBV. One virus from Uroderma bilobatum, the tent-making bat, cross-reacted with monoclonal antibodies against the HBV antigenicity determining S domain. Up to 18.4% of bat sera contained antibodies against bat hepadnaviruses. Infectious clones were generated to study all three viruses in detail. Hepatitis D virus particles pseudotyped with surface proteins of U. bilobatum HBV, but neither of the other two viruses could infect primary human and Tupaia belangeri hepatocytes. Hepatocyte infection occurred through the human HBV receptor sodium taurocholate cotransporting polypeptide but could not be neutralized by sera from vaccinated humans. Antihepadnaviral treatment using an approved reverse transcriptase inhibitor blocked replication of all bat hepadnaviruses. Our data suggest that bats may have been ancestral sources of primate hepadnaviruses. The observed zoonotic potential might affect concepts aimed at eradicating HBV.evolution | zoonosis | virome | metagenomics | reverse genetics M ore than 40% of the human population has been infected with the hepatitis B virus (HBV), giving rise to 240 million chronic HBV carriers and ca. 620,000 HBV-associated deaths annually (1). A prophylactic vaccine containing the small HBV genotype A2 surface antigen (SHB) is part of the worldwide Expanded Program on Immunization. Because of the general success of SHBs-based vaccination, global eradication of HBV has been considered achievable (2, 3). Potential for the virus to be eradicated is supported by the fact that there are no known animal reservoirs. However, recent studies addressing the distribution of pathogens related to human viruses in wild animals, including mumps-and measles-related viruses in bats, have uncovered surprising putative novel reservoirs for human-pathogenic viruses (4). SignificanceHepatitis B virus (HBV) is the prototype hepadnavirus; 40% of humans have current or past infection. In a global investigation of viral diversity in bats, we discovered three unique hepadnavirus species. The relatedness of these viruses to HBV suggests that bats might constitute ancestral sources of primate hepadnaviruse...

We have identified Tim9, a new component of the TIM22.54 import machinery, which mediates transport of proteins into the inner membrane of mitochondria. Tim9, an essential protein of Saccharomyces cerevisiae, shares sequence similarity with Tim10 and Tim12. Tim9 is located in the mitochondrial intermembrane space and is organized into two distinct hetero-oligomeric assemblies with Tim10 and Tim12. One complex contains Tim9 and Tim10. The other complex contains Tim9, Tim10 and Tim12 and is tightly associated with Tim22 in the inner membrane. The TIM9.10 complex is more abundant than the TIM9.10.12 complex and mediates partial translocation of mitochondrial carriers proteins across the outer membrane. The TIM9.10.12 complex assists further translocation into the inner membrane in association with TIM22.54.

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SummaryThe pattern-recognition molecule Nod1 is a critical sensor for bacterial derived diaminopimelic acidcontaining peptidoglycan fragments which induces innate immune responses in epithelial cells. Here we report the subcellular localization of this protein in human epithelial cells. Nod1 is localized in the cytosol and at the plasma membrane in human cells. This membrane association is dependent on the integrity of the protein, on its signalling capacity and on an intact actin cytoskeleton. Signalling-inactive mutants of Nod1 or disruption of the actin cytoskeleton interferes with this localization pattern and impacts on downstream NF-kB activation. Moreover, the invasive bacterium Shigella flexneri was used as a model for physiological activation of Nod1. Imaging revealed that Nod1 is recruited to the site of bacterial entry, where it colocalizes with NEMO. Our data provide evidence that membrane association is linked to Nod1 function and, in view of recent findings on Nod2, that this may be a common feature of NLR family members.

Tim23, a key component of the mitochondrial preprotein translocase, is anchored in the inner membrane by its C-terminal domain and exposes an intermediate domain in the intermembrane space that functions as a presequence receptor. We show that the N-terminal domain of Tim23 is exposed on the surface of the outer membrane. The two-membrane-spanning topology of Tim23 is a novel characteristic in membrane biology. By the simultaneous integration into two membranes, Tim23 forms contacts between the outer and inner mitochondrial membranes. Tethering the inner membrane translocase to the outer membrane facilitates the transfer of precursor proteins from the TOM complex to the TIM23 complex and increases the efficiency of protein import.