Acrylamide inhibits vaccinia virus through vimentin-independent anti-viral granule formation.

The replication and assembly of vaccinia virus (VACV), the prototypic poxvirus, occurs exclusively in the cytoplasm of host cells. While the role of cellular cytoskeletal components in these processes remains poorly understood, vimentin-a type III intermediate filament-has been shown to associate with viral replication sites and to be incorporated into mature VACV virions. Here, we employed chemical and genetic approaches to further investigate the role of vimentin during the VACV lifecycle. The collapse of vimentin filaments, using acrylamide, was found to inhibit VACV infection at the level of genome replication, intermediate- and late-gene expression. However, we found that CRISPR-mediated knockout of vimentin did not impact VACV replication. Combining these tools, we demonstrate that acrylamide treatment results in the formation of anti-viral granules (AVGs) known to mediate translational inhibition of many viruses. We conclude that vimentin is dispensable for poxvirus replication and assembly and that acrylamide, as a potent inducer of AVGs during VACV infection, serves to bolster cell's anti-viral response to poxvirus infection.

ARID3B: a Novel Regulator of the Kaposi's Sarcoma-Associated Herpesvirus Lytic Cycle.

UNLABELLED: Kaposi's sarcoma-associated herpesvirus (KSHV) is the causative agent of commonly fatal malignancies of immunocompromised individuals, including primary effusion lymphoma (PEL) and Kaposi's sarcoma (KS). A hallmark of all herpesviruses is their biphasic life cycle-viral latency and the productive lytic cycle-and it is well established that reactivation of the KSHV lytic cycle is associated with KS pathogenesis. Therefore, a thorough appreciation of the mechanisms that govern reactivation is required to better understand disease progression. The viral protein replication and transcription activator (RTA) is the KSHV lytic switch protein due to its ability to drive the expression of various lytic genes, leading to reactivation of the entire lytic cycle. While the mechanisms for activating lytic gene expression have received much attention, how RTA impacts cellular function is less well understood. To address this, we developed a cell line with doxycycline-inducible RTA expression and applied stable isotope labeling of amino acids in cell culture (SILAC)-based quantitative proteomics. Using this methodology, we have identified a novel cellular protein (AT-rich interacting domain containing 3B [ARID3B]) whose expression was enhanced by RTA and that relocalized to replication compartments upon lytic reactivation. We also show that small interfering RNA (siRNA) knockdown or overexpression of ARID3B led to an enhancement or inhibition of lytic reactivation, respectively. Furthermore, DNA affinity and chromatin immunoprecipitation assays demonstrated that ARID3B specifically interacts with A/T-rich elements in the KSHV origin of lytic replication (oriLyt), and this was dependent on lytic cycle reactivation. Therefore, we have identified a novel cellular protein whose expression is enhanced by KSHV RTA with the ability to inhibit KSHV reactivation. IMPORTANCE: Kaposi's sarcoma-associated herpesvirus (KSHV) is the causative agent of fatal malignancies of immunocompromised individuals, including Kaposi's sarcoma (KS). Herpesviruses are able to establish a latent infection, in which they escape immune detection by restricting viral gene expression. Importantly, however, reactivation of productive viral replication (the lytic cycle) is necessary for the pathogenesis of KS. Therefore, it is important that we comprehensively understand the mechanisms that govern lytic reactivation, to better understand disease progression. In this study, we have identified a novel cellular protein (AT-rich interacting domain protein 3B [ARID3B]) that we show is able to temper lytic reactivation. We showed that the master lytic switch protein, RTA, enhanced ARID3B levels, which then interacted with viral DNA in a lytic cycle-dependent manner. Therefore, we have added a new factor to the list of cellular proteins that regulate the KSHV lytic cycle, which has implications for our understanding of KSHV biology.

NEDDylation is essential for Kaposi's sarcoma-associated herpesvirus latency and lytic reactivation and represents a novel anti-KSHV target.

Kaposi's sarcoma-associated herpesvirus (KSHV) is the causative agent of Kaposi's sarcoma (KS) and primary effusion lymphoma (PEL), which are aggressive malignancies associated with immunocompromised patients. For many non-viral malignancies, therapeutically targeting the ubiquitin proteasome system (UPS) has been successful. Likewise, laboratory studies have demonstrated that inhibition of the UPS might provide a promising avenue for the treatment of KSHV-associated diseases. The largest class of E3 ubiquitin ligases are the cullin-RING ligases (CRLs) that are activated by an additional ubiquitin-like protein, NEDD8. We show that pharmacological inhibition of NEDDylation (using the small molecule inhibitor MLN4924) is cytotoxic to PEL cells by inhibiting NF-κB. We also show that CRL4B is a novel regulator of latency as its inhibition reactivated lytic gene expression. Furthermore, we uncovered a requirement for NEDDylation during the reactivation of the KSHV lytic cycle. Intriguingly, inhibition prevented viral DNA replication but not lytic cycle-associated gene expression, highlighting a novel mechanism that uncouples these two features of KSHV biology. Mechanistically, we show that MLN4924 treatment precluded the recruitment of the viral pre-replication complex to the origin of lytic DNA replication (OriLyt). These new findings have revealed novel mechanisms that regulate KSHV latency and reactivation. Moreover, they demonstrate that inhibition of NEDDylation represents a novel approach for the treatment of KSHV-associated malignancies.

Merkel cell polyomavirus small T antigen mediates microtubule destabilization to promote cell motility and migration.

UNLABELLED: Merkel cell carcinoma (MCC) is an aggressive skin cancer of neuroendocrine origin with a high propensity for recurrence and metastasis. Merkel cell polyomavirus (MCPyV) causes the majority of MCC cases due to the expression of the MCPyV small and large tumor antigens (ST and LT, respectively). Although a number of molecular mechanisms have been attributed to MCPyV tumor antigen-mediated cellular transformation or replication, to date, no studies have investigated any potential link between MCPyV T antigen expression and the highly metastatic nature of MCC. Here we use a quantitative proteomic approach to show that MCPyV ST promotes differential expression of cellular proteins implicated in microtubule-associated cytoskeletal organization and dynamics. Intriguingly, we demonstrate that MCPyV ST expression promotes microtubule destabilization, leading to a motile and migratory phenotype. We further highlight the essential role of the microtubule-associated protein stathmin in MCPyV ST-mediated microtubule destabilization and cell motility and implicate the cellular phosphatase catalytic subunit protein phosphatase 4C (PP4C) in the regulation of this process. These findings suggest a possible molecular mechanism for the highly metastatic phenotype associated with MCC. IMPORTANCE: Merkel cell polyomavirus (MCPyV) causes the majority of cases of Merkel cell carcinoma (MCC), an aggressive skin cancer with a high metastatic potential. However, the molecular mechanisms leading to virally induced cancer development have yet to be fully elucidated. In particular, no studies have investigated any potential link between the virus and the highly metastatic nature of MCC. We demonstrate that the MCPyV small tumor antigen (ST) promotes the destabilization of the host cell microtubule network, which leads to a more motile and migratory cell phenotype. We further show that MCPyV ST induces this process by regulating the phosphorylation status of the cellular microtubule-associated protein stathmin by its known association with the cellular phosphatase catalytic subunit PP4C. These findings highlight stathmin as a possible biomarker of MCC and as a target for novel antitumoral therapies.

No evident association between efavirenz use and suicidality was identified from a disproportionality analysis using the FAERS database.

OBJECTIVE: To assess the potential association of selected antiretrovirals (ARVs), including efavirenz, with suicidality. DESIGN: Retrospective analysis of the Food and Drug Administration Adverse Event Reporting System (FAERS), by performing a Multi-Item Gamma Poisson Shrinker (MGPS) disproportionality analysis. METHODS: MGPS disproportionality analysis, a technique to identify associations between drugs and adverse events, was performed using cumulative data from the FAERS database collected up to August 2012. This method yields an Empirical Bayesian Geometric Mean score and corresponding 90% confidence interval (EB05, EB95). EB05 scores ≥ 2 were pre-defined as a signal for a potential drug-event association. The FAERS database includes spontaneous adverse-event reports from consumers and healthcare professionals. All FAERS reports of suicidality (including suicidal ideation, suicide attempt and completed suicide or a composite of these) in patients taking efavirenz (as single agent or in fixed-dose combination), atazanavir, darunavir, etravirine, nevirapine and raltegravir were identified. A number of parallel analyses were performed to assess the validity of the methodology: fluoxetine and sertraline, antidepressants with a known association with suicidality, and raltegravir, an ARV with rhabdomyolysis and myopathy listed as "uncommon" events in the US-prescribing information. RESULTS: A total of 29,856 adverse event reports were identified among patients receiving efavirenz, atazanavir, darunavir, etravirine, nevirapine and raltegravir, of which 457 were reports of suicidality events. EB05 scores observed for the composite suicidality term for efavirenz (EB05=0.796), and other ARVs (EB05=0.279-0.368), were below the pre-defined threshold. Fluoxetine and sertraline gave EB05 scores for suicidality >2. Raltegravir gave EB05 scores >2 for myopathy and rhabdomyolysis. CONCLUSIONS: The pre-determined threshold for signals for suicidality, including suicidal ideation, suicide attempt, completed suicide and a composite suicidality endpoint, was not exceeded for efavirenz and other ARVs in this analysis. Efavirenz has been associated with suicidality in clinical trials. Further studies that adjust for confounding factors are needed to better understand any potential association with ARVs and suicidality.

Merkel cell polyomavirus: molecular insights into the most recently discovered human tumour virus.

A fifth of worldwide cancer cases have an infectious origin, with viral infection being the foremost. One such cancer is Merkel cell carcinoma (MCC), a rare but aggressive skin malignancy. In 2008, Merkel cell polyomavirus (MCPyV) was discovered as the causative agent of MCC. It is found clonally integrated into the majority of MCC tumours, which require MCPyV oncoproteins to survive. Since its discovery, research has begun to reveal the molecular virology of MCPyV, as well as how it induces tumourigenesis. It is thought to be a common skin commensal, found at low levels in healthy individuals. Upon loss of immunosurveillance, MCPyV reactivates, and a heavy viral load is associated with MCC pathogenesis. Although MCPyV is in many ways similar to classical oncogenic polyomaviruses, such as SV40, subtle differences are beginning to emerge. These unique features highlight the singular position MCPyV has as the only human oncogenic polyomavirus, and open up new avenues for therapies against MCC.

Autologous cultured chondrocytes: adverse events reported to the United States Food and Drug Administration.

BACKGROUND: Carticel is an autologous cultured chondrocyte product that has been approved by the United States Food and Drug Administration for the repair of symptomatic cartilaginous defects of the femoral condyle that are caused by acute or repetitive trauma in patients who have been previously managed with arthroscopy or other surgical procedures. The present report describes the adverse events following Carticel implantation as reported to the Food and Drug Administration from 1996 to 2003. METHODS: We reviewed adverse event reports that had been submitted to the Food and Drug Administration's MedWatch system for information on demographic characteristics, adverse events, and surgical revisions. Adverse events were categorized into sixteen non-mutually exclusive groups. Five categories were used to classify reoperations. Food and Drug Administration regulations require manufacturers to report adverse events; however, reporting by clinicians and others is voluntary. Therefore, adverse event reporting is likely to underestimate the number of event occurrences. Adverse events may be either causally or coincidentally related to the product. RESULTS: A total of 497 adverse events among 294 patients receiving Carticel were reported. The median interval from Carticel implantation to the diagnosis of an adverse event was 240 days (range, one to 2105 days). The median age of the patients was thirty-eight years, and 63% of the patients were male. Of the 270 events for which the anatomic site was noted, 258 (96%) involved the femoral condyles. More than one adverse event was reported for 135 patients (46%). The most commonly reported events were graft failure (seventy-three patients; 25%), delamination (sixty-five patients; 22%), and tissue hypertrophy (fifty-two patients; 18%). In addition, eighteen surgical site infections were reported, including eleven joint and seven soft-tissue infections. Surgical revision subsequent to Carticel implantation was mentioned in the records for 273 patients (93%). The reasons for the 389 revision procedures included graft-related problems (187 procedures; 48.1%), periarticular soft-tissue problems (ninety-seven procedures; 24.9%), and intra-articular problems (sixty-three procedures; 16.2%). Eight patients had a total knee replacement. Based on the manufacturer's reported distribution of 7500 Carticel lots between 1995 and 2002, 285 patients (3.8%) had an adverse event that was reported to the Food and Drug Administration. CONCLUSIONS: The most common adverse events reported in association with the Carticel technique involved graft failure, delamination, and tissue hypertrophy.

Thromboembolic adverse events after use of recombinant human coagulation factor VIIa.

CONTEXT: The US Food and Drug Administration (FDA) licensed recombinant human coagulation factor VIIa (rFVIIa) on March 25, 1999, for bleeding in patients with hemophilia A or B and inhibitors to factors VIII or IX. Use in patients without hemophilia has been increasing since licensure. OBJECTIVE: To review serious thromboembolic adverse events (AEs) reported to the FDA's Adverse Event Reporting System (AERS). DESIGN, SETTING, AND PATIENTS: The AERS database was reviewed from March 25, 1999, through December 31, 2004, for thromboembolic AE reports with rFVIIa. The AERS database includes US and non-US spontaneous AE reports from both approved (specific indications for patients with hemophilia) and unlabeled uses. It also includes serious AEs in patients enrolled in postlicensure clinical trials who received rFVIIa. Manufacturer reporting to FDA is mandatory, but primary notification from clinicians and others to FDA or manufacturers is voluntary for spontaneous reports; therefore, AERS underrepresents actual event occurrences. MAIN OUTCOME MEASURE: Reported thromboembolic events occurring in patients administered rFVIIa. RESULTS: A total of 431 AE reports for rFVIIa were found, of which 168 reports described 185 thromboembolic events. Seventeen events occurred in patients with hemophilia and 59 occurred in patients enrolled in postlicensure trials. Unlabeled indications accounted for 151 of the reports, most with active bleeding (n = 115). Reported AEs were thromboembolic cerebrovascular accident (n = 39), acute myocardial infarction (n = 34), other arterial thromboses (n = 26), pulmonary embolism (n = 32), other venous thromboses (including deep vein thrombosis) (n = 42), and clotted devices (n = 10). In 36 (72%) of 50 reported deaths, the probable cause of death was the thromboembolic event. In 144 patients with timing information, 73 events (52%) occurred in the first 24 hours after the last dose (30 events within 2 hours). Sixty-four reports (38%) noted concomitant use of hemostatic agents. Most reports lacked sufficient information to evaluate potential dosage associations. CONCLUSIONS: Most reported thromboembolic AEs followed the use of rFVIIa for unlabeled indications and occurred in arterial and venous systems, often resulting in serious morbidity and mortality. Analysis of the relationship between AEs and rFVIIa is hindered by concomitant medications, preexisting medical conditions, confounding by indication, and inherent limitations of passive surveillance. Randomized controlled trials are needed to establish the safety and efficacy of rFVIIa in patients without hemophilia.