Comparative Virus-Host Protein Interactions of the Bluetongue Virus NS4 Virulence Factor

Bluetongue virus (BTV) is the etiologic agent of a non-contagious arthropod-borne disease transmitted to wild and domestic ruminants. BTV induces a large panel of clinical manifestations ranging from asymptomatic infection to lethal hemorrhagic fever. Despite the fact that BTV has been studied extensively, we still have little understanding of the molecular determinants of BTV virulence. In our report, we have performed a comparative yeast two-hybrid (Y2H) screening approach to search direct cellular targets of the NS4 virulence factor encoded by two different serotypes of BTV: BTV8 and BTV27. This led to identifying Wilms’ tumor 1-associated protein (WTAP) as a new interactor of the BTV-NS4. In contrast to BTV8, 1, 4 and 25, NS4 proteins from BTV27 and BTV30 are unable to interact with WTAP. This interaction with WTAP is carried by a peptide of 34 amino acids (NS4²²⁻⁵⁵) within its putative coil-coiled structure. Most importantly, we showed that binding to WTAP is restored with a chimeric protein where BTV27-NS4 is substituted by BTV8-NS4 in the region encompassing residue 22 to 55. We also demonstrated that WTAP silencing reduces viral titers and the expression of viral proteins, suggesting that BTV-NS4 targets a cellular function of WTAP to increase its viral replication.     

Voltage-Gated Na+ Channel Activation Induces Both Action Potentials in Utricular Hair Cells and Brain-Derived Neurotrophic Factor Release in the Rat Utricle During a Restricted Period of Development

The mammalian utricular sensory receptors are commonly believed to be non-spiking cells with electrical activity limited to graded membrane potential changes. Here we provide evidence that during the first post-natal week, the sensory hair cells of the rat utricle express a tetrodotoxin (TTX)-sensitive voltage-gated Na⁺ current that displays most of the biophysical and pharmacological characteristics of neuronal Na⁺ current. Single-cell RT-PCR reveals that several α-subunit isoforms of the Na⁺ channels are co-expressed within a single hair cell, with a major expression of Nav1.2 and Nav1.6 subunits. In neonatal hair cells, 30 % of the Na⁺ channels are available for activation at the resting potential. Depolarizing current injections in the range of the transduction currents are able to trigger TTX-sensitive action potentials. We also provide evidence of a TTX-sensitive activity-dependent brain-derived neurotrophic factor (BDNF) release by early post-natal utricle explants. Developmental analysis shows that Na⁺ currents decrease dramatically from post-natal day 0 (P0) to P8 and become almost undetectable at P21. Concomitantly, depolarizing stimuli fail to induce both action potential and BDNF release at P20. The present findings reveal that vestibular hair cells express neuronal-like TTX-sensitive Na⁺ channels able to generate Na⁺-driven action potentials only during the early post-natal period of development. During the same period an activity-dependent BDNF secretion by utricular explants has been demonstrated. This could be an important mechanism involved in vestibular sensory system differentiation and synaptogenesis.     

Impact of Left Ventricular Diastolic Dysfunction on Lung Transplantation Outcome in Patients With Pulmonary Arterial Hypertension

Diastolic dysfunction may influence perioperative outcome, early graft function, and long‐term survival. We compared the outcomes of double lung transplantation (DLTx) for patients with pulmonary arterial hypertension (PAH) with preoperative left ventricular (LV) diastolic dysfunction with the outcomes of patients without diastolic dysfunction. Of 116 consecutive patients with PAH (who underwent transplantation between January 1995 and December 2013), 44 met our inclusion and exclusion criteria. Fourteen (31.8%) patients with diastolic dysfunction pretransplantation had a higher body mass index (29 [IQR 21.5–32.6] vs 22.4 [IQR 19.9–25.3] kg/m²) and mean pulmonary arterial pressure (54.6 ± 10 mmHg vs 47 ± 11.3 mmHg) and right atrial pressure (16.5 ± 5.2 mmHg vs 10.6 ± 5.2 mmHg). The patients received extracorporeal life support more frequently (33% vs 7% [p = 0.02]), had worse APACHE II scores (21.7 ± 7.4 vs 15.3 ± 5.3 [p = 0.02]), and a trend toward worse ventilator‐free days (2.5 [IQR 6.5–32.5] vs 17 [IQR 3–23] [p = 0.08]). There was no effect on development of primary graft dysfunction or intensive care unit/hospital survival. One‐year survival was worse (hazard ratio [HR] 4.45, 95% confidence interval [CI] 1.3–22, p = 0.02). Diastolic dysfunction was the only variable that correlated with overall survival (HR 5.4, 95% CI 1.3–22, p = 0.02). Diastolic dysfunction leads to early postoperative morbidity and worse survival in patients with PAH after DLTx.     

Reflectance confocal microscopy for quantification of Sarcoptes scabiei in Norwegian scabies

Background and Objectives In vivo reflectance‐mode confocal microscopy (RCM) can be used for the diagnosis of scabies. This study quantifies S. scabiei and its eggs and droppings in a patient affected by Norwegian Scabies (NS), and describes their distribution within the epidermis and in different body areas. Methods Different skin sites were randomly chosen in four sections (head, upper limbs, trunk and inferior limbs) of the body surface area (BSA) to acquire a total of 60 RCM z‐stacks. The number of mites and eggs, the presence of droppings, as well as the minimum epidermal depth at which mites, eggs and faeces were detectable, was established for each z‐stack. The total number of mites and eggs on the entire BSA was calculated considering the weighted mean for the four sections of the BSA. Results A total of 15.8 millions of S. scabiei and 7.2 millions of eggs were calculated. Mites, eggs and faeces were homogeneously distributed all over the body surface. Droppings, easily recognized by the RCM, were present in more than an half of the analyzed cutaneous sites and were associated with the presence of parasites (chi‐squared test, P = 0.002). Conclusions Our study illustrates the ability of RCM to identify, locate, and quantify the various forms of S. scabiei in human skin. NS is an extremely contagious disease, considering that the number of mites can be around 15.8 millions. Moreover, all areas of the body are parasitized in NS, including the face.