Essential Host Factors for Human Parvovirus B19 Replication

Parvovirus B19 (B19V) is a small, non-enveloped virus that contains a single-stranded DNA (ssDNA) genome of 5.6 kb in size. B19V is pathogenic to humans and causes bone marrow failure diseases and various other inflammatory disorders. B19V infection exhibits high tropism for human erythroid progenitor cells (EPCs) in the bone marrow and fetal liver. The exclusive restriction of B19V replication to erythroid lineage cells is partly due to the expression of receptor and co-receptor(s) on the cell surface of human EPCs and partly depends on the intracellular factors essential for virus replication. On this rationale, we tried to investigate the essential host factors for efficient virus replication. Our results demonstrated that signal transducer and activator of transcription 5 (STAT5) and RNA-binding motif protein-38 (RBM38) are two of these important host factors that ensure virus DNA replication and pre-mRNA processing, respectively, during B19V infection. The stages of erythropoiesis during which STAT5 is activated and RBM38 is expressed, are highly susceptible to B19V infection, thus suggesting that these two factors are among the key determinants of the B19V restriction to human EPCs. B19V requires erythropoietin (EPO) signaling and hypoxia for its efficient replication. EPO to EPO receptor signaling activates JAK2-STAT5 pathway that phosphorylates STAT5. In our first study, we show that phosphorylated STAT5 is critical for B19V replication. Upon in-silico analysis, we identified a consensus STAT5 binding element adjacent to the NS1-binding elements within the minimal origin of viral DNA replication (Ori) in the B19V genome. The phosphorylated STAT5 specifically interacts with viral Ori both in vivo and in vitro, and is actively recruited within the viral DNA replication centers. Furthermore, our study shows a novel interaction between STAT5 and the minichromosome maintenance (MCM) complex. Our proposed model suggests that STAT5 directly facilitates viral DNA replication by recruiting MCM complex into viral DNA replication centers. Interestingly, we found that pimozide, a STAT5 phosphorylation inhibitor and an FDA-approved drug, inhibits B19V replication in ex vivo expanded EPCs, suggesting that pimozide could be a promising antiviral drug for the treatment of B19V-related pathologies. B19V expresses a single precursor mRNA (pre-mRNA), which undergoes alternative splicing and alternate polyadenylation to generate 12 viral mRNA transcripts. Splicing at the second 5’ donor site (D2) of the B19V pre-mRNA is essential for the expression of VP1, VP2 and 11-kDa. We have previously identified that a cis-acting intronic splicing enhancer 2 (ISE2) that lies immediately after the D2 site facilitates recognition of the D2 donor for its efficient splicing. In our second study, we described that ISE2 harbors a consensus RBM38 binding sequence–5’-UGUGUG-3’. RBM38 is expressed during the middle stage of erythropoiesis. We first confirmed that the RBM38 binds specifically with the ISE2 element in vitro. Knockdown of RBM38 significantly decreases the level of the spliced mRNA at D2 that encodes 11-kDa protein and, thereafter, the expression of the 11-kDa protein. Importantly, we found that the 11-kDa protein enhances viral DNA replication and virion release. Accordingly, knockdown of RBM38 decreases virus replication via downregulating 11-kDa expression. Taken together, these results suggest that the 11-kDa protein facilitates B19V DNA replication, and that RBM38 is an essential host factor for the splicing of B19V pre-mRNA from D2 to A2-2 sites and for the expression of the 11-kDa protein. In conclusion, we identified two host factors, STAT5 and RBM38, which play important roles in B19V replication. We provide a mechanistic overview of how STAT5 facilitates virus DNA replication and RBM38 promotes the splicing of B19V pre-mRNA that ensures the expression of 11-kDa protein

{2-[(3-Bromo­benzyl­idene)amino]-5-chloro­phen­yl}(phen­yl)methanone

In the title compound, C20H13BrClNO, the azomethine double bond [C=N = 1.246 (4) Å] adopts an E conformation. The bromo- and chlorophenyl rings are inclined to one another by 13.70 (11)°, and form dihedral angles of 76.68 (10) and 74.24 (7)°, respectively, with the phenyl ring. In the crystal, mol­ecules are linked by C—H⋯O hydrogen bonds to form double stranded chains propagating along the b-axis direction

Ubiquitin variants potently inhibit SARS-CoV-2 PLpro and viral replication via a novel site distal to the protease active site

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has made it clear that combating coronavirus outbreaks benefits from a combination of vaccines and therapeutics. A promising drug target common to all coronaviruses-including SARS-CoV, MERS-CoV, and SARS-CoV-2-is the papain-like protease (PLpro). PLpro cleaves part of the viral replicase polyproteins into non-structural protein subunits, which are essential to the viral replication cycle. Additionally, PLpro can cleave both ubiquitin and the ubiquitin-like protein ISG15 from host cell substrates as a mechanism to evade innate immune responses during infection. These roles make PLpro an attractive antiviral drug target. Here we demonstrate that ubiquitin variants (UbVs) can be selected from a phage-displayed library and used to specifically and potently block SARS-CoV-2 PLpro activity. A crystal structure of SARS-CoV-2 PLpro in complex with a representative UbV reveals a dimeric UbV bound to PLpro at a site distal to the catalytic site. Yet, the UbV inhibits the essential cleavage activities of the protease in vitro and in cells, and it reduces viral replication in cell culture by almost five orders of magnitude

Functional gastrointestinal disorders are increased in joint hypermobility-related disorders with concomitant postural orthostatic tachycardia syndrome.

Background Individuals with hypermobility spectrum disorders/hypermobile Ehlers‐Danlos syndrome (HSD/hEDS) frequently fulfill criteria for Rome IV functional gastrointestinal disorders (FGIDs). Postural orthostatic tachycardia syndrome (POTS) is also commonly reported in HSD/hEDS and may impact on co‐morbidity with and severity of FGIDs, although this remains to be studied. We determined the impact of concomitant POTS and HSD/hEDS on their association with Rome IV FGIDs. Methods With the help of the charity organization Ehlers‐Danlos Support UK, an online cross‐sectional health survey was completed by individuals with HSD/hEDS. The survey enquired for (a) self‐reported doctor diagnosis of POTS, chronic fatigue syndrome, and fibromyalgia, (b) the presence and symptom frequency of Rome IV FGIDs, and (c) anxiety and depression scores. Key Results Of 616 subjects with HSD/hEDS, 37.5% reported a doctor diagnosis of POTS. POTS‐positive individuals were significantly younger than POTS‐negative subjects (37 vs 40 years, P = 0.002), more likely to report chronic fatigue syndrome (44% vs 31%, P < 0.0001), and showed a trend toward increased prevalence of fibromyalgia (44% vs 37%, P = 0.06) and higher depression score (P = 0.07). POTS‐positive subjects were also more likely to fulfill criteria for Rome IV FGIDs across various organ domains and experienced both upper and lower gastrointestinal symptoms significantly more frequently. The increased associations for FGIDs and GI symptom frequency remained unchanged in HSD/hEDS subjects with POTS following adjustments for age, chronic fatigue syndrome, fibromyalgia, and depression scores. Conclusions and Inferences The high FGID burden in HSD/hEDS is further amplified in the presence of POTS. Future studies should elucidate the mechanism by which POTS arises in HSD/hEDS and is associated with increased GI symptoms

Extracting scientific trends by mining topics from Call for Papers

© 2019, Emerald Publishing Limited. Purpose: The purpose of this paper is to present a novel approach for mining scientific trends using topics from Call for Papers (CFP). The work contributes a valuable input for researchers, academics, funding institutes and research administration departments by sharing the trends to set directions of research path. Design/methodology/approach: The authors procure an innovative CFP data set to analyse scientific evolution and prestige of conferences that set scientific trends using scientific publications indexed in DBLP. Using the Field of Research code 804 from Australian Research Council, the authors identify 146 conferences (from 2006 to 2015) into different thematic areas by matching the terms extracted from publication titles with the Association for Computing Machinery Computing Classification System. Furthermore, the authors enrich the vocabulary of terms from the WordNet dictionary and Growbag data set. To measure the significance of terms, the authors adopt the following weighting schemas: probabilistic, gram, relative, accumulative and hierarchal. Findings: The results indicate the rise of “big data analytics” from CFP topics in the last few years. Whereas the topics related to “privacy and security” show an exponential increase, the topics related to “semantic web” show a downfall in recent years. While analysing publication output in DBLP that matches CFP indexed in ERA Core A* to C rank conference, the authors identified that A* and A tier conferences not merely set publication trends, since B or C tier conferences target similar CFP. Originality/value: Overall, the analyses presented in this research are prolific for the scientific community and research administrators to study research trends and better data management of digital libraries pertaining to the scientific literature

Oropouche orthobunyavirus infection is mediated by the cellular host factor Lrp1

Oropouche orthobunyavirus (OROV

Lrp1 is essential for lethal Rift Valley fever hepatic disease in mice

Rift Valley fever virus (RVFV) is an emerging arbovirus found in Africa. While RVFV is pantropic and infects many cells and tissues, viral replication and necrosis within the liver play a critical role in mediating severe disease. The low-density lipoprotein receptor-related protein 1 (Lrp1) is a recently identified host factor for cellular entry and infection by RVFV. The biological significance of Lrp1, including its role in hepatic disease in vivo, however, remains to be determined. Because Lrp1 has a high expression level in hepatocytes, we developed a mouse model in which Lrp1 is specifically deleted in hepatocytes to test how the absence of liver Lrp1 expression affects RVF pathogenesis. Mice lacking Lrp1 expression in hepatocytes showed minimal RVFV replication in the liver, longer time to death, and altered clinical signs toward neurological disease. In contrast, RVFV infection levels in other tissues showed no difference between the two genotypes. Therefore, Lrp1 is essential for RVF hepatic disease in mice

Recent Advances in Replication and Infection of Human Parvovirus B19

Parvovirus B19 (B19V) is pathogenic to humans and causes bone marrow failure diseases and various other inflammatory disorders. B19V infection exhibits high tropism for human erythroid progenitor cells (EPCs) in the bone marrow and fetal liver. The exclusive restriction of B19V replication to erythroid lineage cells is partly due to the expression of receptor and co-receptor(s) on the cell surface of human EPCs and partly depends on the intracellular factors essential for virus replication. We first summarize the latest developments in the viral entry process and the host cellular factors or pathways critical for B19V replication. We discuss the role of hypoxia, erythropoietin signaling and STAT5 activation in the virus replication. The B19V infection-induced DNA damage response (DDR) and cell cycle arrest at late S-phase are two key events that promote B19V replication. Lately, the virus infection causes G2 arrest, followed by the extensive cell death of EPCs that leads to anemia. We provide the current understanding of how B19V exploits the cellular resources and manipulate pathways for efficient virus replication. B19V encodes a single precursor mRNA (pre-mRNA), which undergoes alternate splicing and alternative polyadenylation to generate at least 12 different species of mRNA transcripts. The post-transcriptional processing of B19V pre-mRNA is tightly regulated through cis-acting elements and trans-acting factors flanking the splice donor or acceptor sites. Overall, in this review, we focus on the recent advances in the molecular virology and pathogenesis of B19V infection

The metabolites of the genus onopordum (asteraceae): Chemistry and biological properties

Onopordum is an interesting genus belonging to the tribe Cardueae (Asteraceae family), and the species of this genus are used as food and in the popular medicine of several countries. The present paper reviews all the metabolites present in all the species of this genus, reported up to 2009, and several chemotaxonomic consideration have been made. Furthermore, the occurrence in other genus, the spectral data, the synthetic approaches, the chemical modifications and the biological properties of the sesquiterpenes of genus Onopordum have been reviewe

Phosphorylated STAT5 directly facilitates parvovirus B19 DNA replication in human erythroid progenitors through interaction with the MCM complex.

Productive infection of human parvovirus B19 (B19V) exhibits high tropism for burst forming unit erythroid (BFU-E) and colony forming unit erythroid (CFU-E) progenitor cells in human bone marrow and fetal liver. This exclusive restriction of the virus replication to human erythroid progenitor cells is partly due to the intracellular factors that are essential for viral DNA replication, including erythropoietin signaling. Efficient B19V replication also requires hypoxic conditions, which upregulate the signal transducer and activator of transcription 5 (STAT5) pathway, and phosphorylated STAT5 is essential for virus replication. In this study, our results revealed direct involvement of STAT5 in B19V DNA replication. Consensus STAT5-binding elements were identified adjacent to the NS1-binding element within the minimal origins of viral DNA replication in the B19V genome. Phosphorylated STAT5 specifically interacted with viral DNA replication origins both in vivo and in vitro, and was actively recruited within the viral DNA replication centers. Notably, STAT5 interacted with minichromosome maintenance (MCM) complex, suggesting that STAT5 directly facilitates viral DNA replication by recruiting the helicase complex of the cellular DNA replication machinery to viral DNA replication centers. The FDA-approved drug pimozide dephosphorylates STAT5, and it inhibited B19V replication in ex vivo expanded human erythroid progenitors. Our results demonstrated that pimozide could be a promising antiviral drug for treatment of B19V-related diseases