Atomic view of the HIV-1 matrix lattice; implications on virus assembly and envelope incorporation.

During the late phase of HIV type 1 (HIV-1) infection cycle, the virally encoded Gag polyproteins are targeted to the inner leaflet of the plasma membrane (PM) for assembly, formation of immature particles, and virus release. Gag binding to the PM is mediated by interactions of the N-terminally myristoylated matrix (myrMA) domain with phosphatidylinositol 4,5-bisphosphate. Formation of a myrMA lattice on the PM is an obligatory step for the assembly of immature HIV-1 particles and envelope (Env) incorporation. Atomic details of the myrMA lattice and how it mediates Env incorporation are lacking. Herein, we present the X-ray structure of myrMA at 2.15 Å. The myrMA lattice is arranged as a hexamer of trimers with a central hole, thought to accommodate the C-terminal tail of Env to promote incorporation into virions. The trimer­trimer interactions in the lattice are mediated by the N-terminal loop of one myrMA molecule and α-helices I­II, as well as the 310 helix of a myrMA molecule from an adjacent trimer. We provide evidence that substitution of MA residues Leu13 and Leu31, previously shown to have adverse effects on Env incorporation, induced a conformational change in myrMA, which may destabilize the trimer­trimer interactions within the lattice. We also show that PI(4,5)P2 is capable of binding to alternating sites on MA, consistent with an MA­membrane binding mechanism during assembly of the immature particle and upon maturation. Altogether, these findings advance our understanding of a key mechanism in HIV-1 particle assembly.

Discontinuous L-binding motifs in the transactivation domain of the vesicular stomatitis virus P protein are required for terminal de novo transcription initiation by the L protein.

The phospho- (P) protein, the co-factor of the RNA polymerase large (L) protein, of vesicular stomatitis virus (VSV, a prototype of nonsegmented negative-strand RNA viruses) plays pivotal roles in transcription and replication. However, the precise mechanism underlying the transcriptional transactivation by the P protein has remained elusive. Here, using an in vitro transcription system and a series of deletion mutants of the P protein, we mapped a region encompassing residues 51-104 as a transactivation domain (TAD) that is critical for terminal de novo initiation, the initial step of synthesis of the leader RNA and anti-genome/genome, with the L protein. Site-directed mutagenesis revealed that conserved amino acid residues in three discontinuous L-binding sites within the TAD are essential for the transactivation activity of the P protein or important for maintaining its full activity. Importantly, relative inhibitory effects of TAD point mutations on synthesis of the full-length leader RNA and mRNAs from the 3'-terminal leader region and internal genes, respectively, of the genome were similar to those on terminal de novo initiation. Furthermore, any of the examined TAD mutations did not alter the gradient pattern of mRNAs synthesized from internal genes, nor did they induce the production of readthrough transcripts. These results suggest that these TAD mutations impact mainly terminal de novo initiation but rarely other steps (e.g., elongation, termination, internal initiation) of single-entry stop-start transcription. Consistently, the mutations of the essential or important amino acid residues within the P TAD were lethal or deleterious to VSV replication in host cells. IMPORTANCE RNA-dependent RNA polymerase L proteins of nonsegmented negative-strand RNA viruses belonging to the Mononegavirales order require their cognate co-factor P proteins or their counterparts for genome transcription and replication. However, exact roles of these co-factor proteins in modulating functions of L proteins during transcription and replication remain unknown. In this study, we revealed that three discrete L-binding motifs within a transactivation domain of the P protein of vesicular stomatitis virus, a prototypic nonsegmented negative-strand RNA virus, are required for terminal de novo initiation mediated by the L protein, which is the first step of synthesis of the leader RNA as well as genome/anti-genome.

GDP polyribonucleotidyltransferase domain of vesicular stomatitis virus polymerase regulates leader-promoter escape and polyadenylation-coupled termination during stop-start transcription.

The unconventional mRNA capping enzyme (GDP polyribonucleotidyltransferase, PRNTase) domain of the vesicular stomatitis virus (VSV) L protein possesses a dual-functional "priming-capping loop" that governs terminal de novo initiation for leader RNA synthesis and capping of monocistronic mRNAs during the unique stop-start transcription cycle. Here, we investigated the roles of basic amino acid residues on a helix structure directly connected to the priming-capping loop in viral RNA synthesis and identified single point mutations that cause previously unreported defective phenotypes at different steps of stop-start transcription. Mutations of residue R1183 (R1183A and R1183K) dramatically reduced the leader RNA synthesis activity by hampering early elongation, but not terminal de novo initiation or productive elongation, suggesting that the mutations negatively affect escape from the leader promoter. On the other hand, mutations of residue R1178 (R1178A and R1178K) decreased the efficiency of polyadenylation-coupled termination of mRNA synthesis at the gene junctions, but not termination of leader RNA synthesis at the leader-to-N-gene junction, resulting in the generation of larger amounts of aberrant polycistronic mRNAs. In contrast, both the R1183 and R1178 residues are not essential for cap-forming activities. The R1183K mutation was lethal to VSV, whereas the R1178K mutation attenuated VSV and triggered the production of the polycistronic mRNAs in infected cells. These observations suggest that the PRNTase domain plays multiple roles in conducting accurate stop-start transcription beyond its known role in pre-mRNA capping.

Immune response evolution in peanut epicutaneous immunotherapy for peanut-allergic children.

BACKGROUND: Epicutaneous immunotherapy with investigational Viaskin™ Peanut 250 µg (DBV712) has demonstrated statistically superior desensitization versus placebo in peanut-allergic children in clinical trials. It is unclear whether serologic biomarkers predict response. METHODS: Serum-specific IgG4 and IgE (whole peanut and components) from subjects enrolled in the phase 3 Efficacy and Safety of Viaskin Peanut in Children With IgE-Mediated Peanut Allergy study were examined by exploratory univariate and multivariate analyses to determine trajectories and predictors of treatment response, based upon peanut protein eliciting dose (ED) at Month (M) 12 double-blind placebo-controlled food challenge. RESULTS: Among Viaskin Peanut-treated subjects, peanut sIgG4 significantly increased from baseline through M12 and peanut sIgE peaked at M3 and fell below baseline by M12, with sIgG4 and sIgE peanut components mirroring these trajectories. Placebo subjects had no significant changes. By univariate analysis, M12 peanut sIgG4/sIgE was higher in treatment responders (p < 0.001) and had highest area under the curve (AUC) for predicting ED ≥300 mg and ≥1000 mg (AUC 69.5% and 69.9%, respectively). M12 peanut sIgG4/sIgE >20.1 predicted M12 ED ≥300 mg (80% positive predictive value). The best performing component was Ara h 1 sIgE <15.7 kUA /L (AUC 66.5%). A multivariate model combining Ara h 1 and peanut sIgG4/sIgE had an AUC of 68.2% (ED ≥300 mg) and 67.8% (ED ≥1000 mg). CONCLUSIONS: Peanut sIgG4 rise most clearly differentiated Viaskin Peanut versus placebo subjects. sIgG4/sIgE ratios >20.1 and the combination of Ara h 1 and peanut sIgG4/sIgE had moderate ability to predict treatment response and could potentially be useful for clinical monitoring. Additional data are needed to confirm these relationships.

Structural characterization of HIV-1 matrix mutants implicated in envelope incorporation.

During the late phase of HIV-1 infection, viral Gag polyproteins are targeted to the plasma membrane (PM) for assembly. Gag localization at the PM is a prerequisite for the incorporation of the envelope protein (Env) into budding particles. Gag assembly and Env incorporation are mediated by the N-terminal myristoylated matrix (MA) domain of Gag. Nonconservative mutations in the trimer interface of MA (A45E, T70R, and L75G) were found to impair Env incorporation and infectivity, leading to the hypothesis that MA trimerization is an obligatory step for Env incorporation. Conversely, Env incorporation can be rescued by a compensatory mutation in the MA trimer interface (Q63R). The impact of these MA mutations on the structure and trimerization properties of MA is not known. In this study, we employed NMR spectroscopy, X-ray crystallography, and sedimentation techniques to characterize the structure and trimerization properties of HIV-1 MA A45E, Q63R, T70R, and L75G mutant proteins. NMR data revealed that these point mutations did not alter the overall structure and folding of MA but caused minor structural perturbations in the trimer interface. Analytical ultracentrifugation data indicated that mutations had a minimal effect on the MA monomer-trimer equilibrium. The high-resolution X-ray structure of the unmyristoylated MA Q63R protein revealed hydrogen bonding between the side chains of adjacent Arg-63 and Ser-67 on neighboring MA molecules, providing the first structural evidence for an additional intermolecular interaction in the trimer interface. These findings advance our knowledge of the interplay of MA trimerization and Env incorporation into HIV-1 particles.

Structure of Nonstructural Protein 1 from SARS-CoV-2.

The periodic emergence of novel coronaviruses (CoVs) represents an ongoing public health concern with significant health and financial burdens worldwide. The most recent occurrence originated in the city of Wuhan, China, where a novel coronavirus (severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2]) emerged causing severe respiratory illness and pneumonia. The continual emergence of novel coronaviruses underscores the importance of developing effective vaccines as well as novel therapeutic options that target either viral functions or host factors recruited to support coronavirus replication. The CoV nonstructural protein 1 (nsp1) has been shown to promote cellular mRNA degradation, block host cell translation, and inhibit the innate immune response to virus infection. Interestingly, deletion of the nsp1-coding region in infectious clones prevented the virus from productively infecting cultured cells. Because of nsp1's importance in the CoV life cycle, it has been highlighted as a viable target for both antiviral therapy and vaccine development. However, the fundamental molecular and structural mechanisms that underlie nsp1 function remain poorly understood, despite its critical role in the viral life cycle. Here, we report the high-resolution crystal structure of the amino globular portion of SARS-CoV-2 nsp1 (residues 10 to 127) at 1.77-Å resolution. A comparison of our structure with the SARS-CoV-1 nsp1 structure reveals how mutations alter the conformation of flexible loops, inducing the formation of novel secondary structural elements and new surface features. Paired with the recently published structure of the carboxyl end of nsp1 (residues 148 to 180), our results provide the groundwork for future studies focusing on SARS-CoV-2 nsp1 structure and function during the viral life cycle.IMPORTANCE Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the COVID-19 pandemic. One protein known to play a critical role in the coronavirus life cycle is nonstructural protein 1 (nsp1). As such, it has been highlighted in numerous studies as a target for both the development of antivirals and the design of live-attenuated vaccines. Here, we report the high-resolution crystal structure of nsp1 derived from SARS-CoV-2 at 1.77-Å resolution. This structure will facilitate future studies focusing on understanding the relationship between structure and function for nsp1. In turn, understanding these structure-function relationships will allow nsp1 to be fully exploited as a target for both antiviral development and vaccine design.

Consequences of Phosphorylation in a Mononegavirales Polymerase-Cofactor System.

Vesicular stomatitis virus (VSV) is a member of the order Mononegavirales, which consists of viruses with a genome of nonsegmented negative-sense (NNS) RNA. Many insights into the molecular biology of NNS viruses were first made in VSV, which is often studied as a prototype for members of this order. Like other NNS viruses, the VSV RNA polymerase consists of a complex of the large protein (L) and phosphoprotein (P). Recent discoveries have produced a model in which the N-terminal disordered segment of P (PNTD) coordinates the C-terminal accessory domains to produce a "compacted" L conformation. Despite this advancement, the role of the three phosphorylation sites in PNTD has remained unknown. Using nuclear magnetic resonance spectroscopy to analyze the interactions between PNTD and the L protein C-terminal domain (LCTD), we demonstrated our ability to sensitively test for changes in the interface between the two proteins. This method showed that the binding site for PNTD on LCTD is longer than was previously appreciated. We demonstrated that phosphorylation of PNTD modulates its interaction with LCTD and used a minigenome reporter system to validate the functional significance of the PNTD-LCTD interaction. Using an electron microscopy approach, we showed that L bound to phosphorylated PNTD displays increased conformational heterogeneity in solution. Taken as a whole, our studies suggest a model in which phosphorylation of PNTD modulates its cofactor and conformational regulatory activities with L.IMPORTANCE Polymerase-cofactor interactions like those addressed in this study are absolute requirements for mononegavirus RNA synthesis. Despite cofactor phosphorylation being present in most of these interactions, what effect if any it has on this protein-protein interaction had not been addressed. Our study is the first to address the effects of phosphorylation on P during its interactions with L in residue-by-residue detail. As phosphorylation is the biologically relevant state of the cofactor, our demonstration of its effects on L conformation suggest that the structural picture of L during infection might be more complex than previously appreciated.

Natural and Recombinant SARS-CoV-2 Isolates Rapidly Evolve In Vitro to Higher Infectivity through More Efficient Binding to Heparan Sulfate and Reduced S1/S2 Cleavage.

One of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virulence factors is the ability to interact with high affinity to the ACE2 receptor, which mediates viral entry into cells. The results of our study demonstrate that within a few passages in cell culture, both the natural isolate of SARS-CoV-2 and the recombinant cDNA-derived variant acquire an additional ability to bind to heparan sulfate (HS). This promotes a primary attachment of viral particles to cells before their further interactions with the ACE2. Interaction with HS is acquired through multiple mechanisms. These include (i) accumulation of point mutations in the N-terminal domain (NTD) of the S protein, which increases the positive charge of the surface of this domain, (ii) insertions into the NTD of heterologous peptides containing positively charged amino acids, and (iii) mutation of the first amino acid downstream of the furin cleavage site. This last mutation affects S protein processing, transforms the unprocessed furin cleavage site into the heparin-binding peptide, and makes viruses less capable of syncytium formation. These viral adaptations result in higher affinity of viral particles to heparin, dramatic increase in plaque sizes, more efficient viral spread, higher infectious titers, and 2 orders of magnitude higher infectivity. The detected adaptations also suggest an active role of NTD in virus attachment and entry. As in the case of other RNA-positive (RNA+) viruses, evolution to HS binding may result in virus attenuation in vivo. IMPORTANCE The spike protein of SARS-CoV-2 is a major determinant of viral pathogenesis. It mediates binding to the ACE2 receptor and, later, fusion of viral envelope and cellular membranes. The results of our study demonstrate that SARS-CoV-2 rapidly evolves during propagation in cultured cells. Its spike protein acquires mutations in the NTD and in the P1' position of the furin cleavage site (FCS). The amino acid substitutions or insertions of short peptides in NTD are closely located on the protein surface and increase its positive charge. They strongly increase affinity of the virus to heparan sulfate, make it dramatically more infectious for the cultured cells, and decrease the genome equivalent to PFU (GE/PFU) ratio by orders of magnitude. The S686G mutation also transforms the FCS into the heparin-binding peptide. Thus, the evolved SARS-CoV-2 variants efficiently use glycosaminoglycans on the cell surface for primary attachment before the high-affinity interaction of the spikes with the ACE2 receptor.

NAP1L1 and NAP1L4 Binding to Hypervariable Domain of Chikungunya Virus nsP3 Protein Is Bivalent and Requires Phosphorylation.

Chikungunya virus (CHIKV) is one of the most pathogenic members of the Alphavirus genus in the Togaviridae family. Within the last 2 decades, CHIKV has expanded its presence to both hemispheres and is currently circulating in both Old and New Worlds. Despite the severity and persistence of the arthritis it causes in humans, no approved vaccines or therapeutic means have been developed for CHIKV infection. Replication of alphaviruses, including CHIKV, is determined not only by their nonstructural proteins but also by a wide range of host factors, which are indispensable components of viral replication complexes (vRCs). Alphavirus nsP3s contain hypervariable domains (HVDs), which encode multiple motifs that drive recruitment of cell- and virus-specific host proteins into vRCs. Our previous data suggested that NAP1 family members are a group of host factors that may interact with CHIKV nsP3 HVD. In this study, we performed a detailed investigation of the NAP1 function in CHIKV replication in vertebrate cells. Our data demonstrate that (i) the NAP1-HVD interactions have strong stimulatory effects on CHIKV replication, (ii) both NAP1L1 and NAP1L4 interact with the CHIKV HVD, (iii) NAP1 family members interact with two motifs, which are located upstream and downstream of the G3BP-binding motifs of CHIKV HVD, (iv) NAP1 proteins interact only with a phosphorylated form of CHIKV HVD, and HVD phosphorylation is mediated by CK2 kinase, and (v) NAP1 and other families of host factors redundantly promote CHIKV replication and their bindings have additive stimulatory effects on viral replication. IMPORTANCE Cellular proteins play critical roles in the assembly of alphavirus replication complexes (vRCs). Their recruitment is determined by the viral nonstructural protein 3 (nsP3). This protein contains a long, disordered hypervariable domain (HVD), which encodes virus-specific combinations of short linear motifs interacting with host factors during vRC assembly. Our study defined the binding mechanism of NAP1 family members to CHIKV HVD and demonstrated a stimulatory effect of this interaction on viral replication. We show that interaction with NAP1L1 is mediated by two HVD motifs and requires phosphorylation of HVD by CK2 kinase. Based on the accumulated data, we present a map of the binding motifs of the critical host factors currently known to interact with CHIKV HVD. It can be used to manipulate cell specificity of viral replication and pathogenesis, and to develop a new generation of vaccine candidates.

Intraspecific variation and directional casque asymmetry in adult southern cassowaries (Casuarius casuarius).

The cranial casques of modern cassowaries (Casuarius) have long intrigued researchers; however, in-depth studies regarding their morphological variation are scarce. Through visual inspection, it has been recognized that casque variability exists between conspecifics. Understanding casque variation has both evolutionary and ecological importance. Although hypothesized to be targeted by selection, intraspecific casque variation has not been quantified previously. Through a large sample of C. casuarius (n = 103), we compared casque shape (lateral and rostral views) between sexes and between individuals from non-overlapping geographical regions using two-dimensional (2D) geometric morphometrics. We found no statistically significant differences between the casque shape of females and males and few substantial shape differences between individuals from different geographic areas. Much of the intraspecific variation within C. casuarius is due to casque asymmetries (77.5% rightward deviating, 20.7% leftward deviating, and 1.8% non-deviating from the midline; n = 111), which explain the high variability of southern cassowary casque shape, particularly from the rostral aspect. Finally, we discuss how our non-significant findings implicate social selection theory, and we identify the benefits of quantifying such variation for further elucidating casque function(s) and the social biology of cassowaries.

Psychometric parameters of food allergy quality of life during an allergen immunotherapy trial.

BACKGROUND: The Food Allergy Quality of Life Questionnaire-Parent Form (FAQLQ-PF) is a commonly used patient-reported outcome measure in food allergy (FA) research. It was developed before FA treatment clinical trials were commonplace and is used as a secondary outcome measure in pivotal FA treatment trials. We examined the psychometric properties of the FAQLQ-PF and its relevance to children with peanut allergy engaged in an epicutaneous immunotherapy (EPIT) clinical trial. METHODS: Analysis was performed on 26 universally answered items of the FAQLQ-PF, from assessments undertaken during the phase 3 PEPITES study (baseline, Month 12), which examined the safety and efficacy of EPIT for children with peanut allergy aged 4-11 years. Item response theory (IRT) was used to assess psychometric parameters of the FAQLQ-PF (i.e., discrimination, difficulty, and information). Confirmatory factor analysis was also employed; reliability was assessed using McDonald's omega (ω) and Cronbach's alpha (α). RESULTS: A total of 23 of 26 items presented very high discrimination levels (>1.7), and all 26 fell within the recommended difficulty threshold (between -1.5 and 1.5). The items contributed a reasonable information level for their respective factors/subdomains. The measure also presented a marginally acceptable model fit for the 3-factor structure (e.g., comparative fit index = 0.88, Tucker-Lewis index = 0.87) and good reliability levels across time points (ω and α > 0.90). CONCLUSIONS: Herein, we present a novel reanalysis of the FAQLQ-PF items using IRT. The longitudinal performance of individual items and subscales was corroborated, and items with the highest discrimination were identified, showing that the tool is suitable for longitudinal measurements in FA treatment trials.

Peanut cross-contamination in randomly selected baked goods.

BACKGROUND: The current standard of care for managing peanut allergy includes avoidance of peanut and use of injectable epinephrine; however, strict avoidance is difficult and accidental ingestion is common with potentially serious consequences. Despite vigilance and efforts to minimize the risk of accidental exposure, peanut protein cross-contamination continues to occur in a variety of foods, including baked goods. OBJECTIVE: To assess and quantify the presence of peanut protein contamination in certain baked goods. METHODS: Randomly selected baked goods were collected from bakeries in the New York and Miami metropolitan areas that sold a variety of ethnic cuisines. A second set of samples from the same bakeries was collected at least 1 week after to evaluate between-batch variability. Samples were sent to the Food Allergy Research and Resource Program to analyze peanut contamination by enzyme-linked immunosorbent assay. Consumption estimates were based on 2003 to 2010 National Health and Nutrition Examination Survey survey data. RESULTS: Of 154 samples from 18 bakeries, 4 (2.6%) had detectable peanut contamination with peanut protein levels ranging from 0.1 mg/100 g to 650 mg/100 g. Consumption estimates for single occasion ingestion of a contaminated item ranged from 0.07 mg to 832 mg of peanut protein. CONCLUSION: In this study, unintended peanut protein was present in a small, but not insignificant, proportion of baked goods, with the potential to trigger a reaction in individuals with peanut allergy. Some products contained high levels of unintended peanut protein. The current data support the potential for accidental exposure to peanut protein with its associated risk.

The genetic architecture of type 2 diabetes.

The genetic architecture of common traits, including the number, frequency, and effect sizes of inherited variants that contribute to individual risk, has been long debated. Genome-wide association studies have identified scores of common variants associated with type 2 diabetes, but in aggregate, these explain only a fraction of the heritability of this disease. Here, to test the hypothesis that lower-frequency variants explain much of the remainder, the GoT2D and T2D-GENES consortia performed whole-genome sequencing in 2,657 European individuals with and without diabetes, and exome sequencing in 12,940 individuals from five ancestry groups. To increase statistical power, we expanded the sample size via genotyping and imputation in a further 111,548 subjects. Variants associated with type 2 diabetes after sequencing were overwhelmingly common and most fell within regions previously identified by genome-wide association studies. Comprehensive enumeration of sequence variation is necessary to identify functional alleles that provide important clues to disease pathophysiology, but large-scale sequencing does not support the idea that lower-frequency variants have a major role in predisposition to type 2 diabetes.

Gastrointestinal Intramural Pancreatic Pseudocysts in a Dog: A Case Report and Human Literature Review.

A 9.5 yr old Yorkshire terrier presented with chronic intermittent vomiting and lethargy of 1.5 yr duration that progressed to generalized weakness. Insulin:glucose ratio was consistent with an insulinoma. Triple-phase computed tomography revealed a mid-body pancreatic nodule. The mid-body pancreatic nodule was enucleated; histopathology was consistent with an insulinoma. Two weeks after the operation, the dog presented for anorexia and diarrhea. Abdominal ultrasound revealed a thick-walled cystic lesion along the dorsal stomach wall. An intramural gastric pseudocyst was diagnosed via exploratory laparotomy and intraoperative gastroscopy. Comparison of amylase and lipase levels of the cystic fluid with that of concurrent blood serum samples confirmed the lesion was of pancreatic pseudocyst origin. The gastric pseudocyst was omentalized. Two weeks after the operation, the dog re-presented for anorexia, regurgitation, and diarrhea. An intramural duodenal pseudocyst was identified and treated with a duodenal resection and anastomosis. The dog has remained asymptomatic and recurrence free based on serial abdominal ultrasounds 22 mo following insulinoma removal. To our knowledge, this phenomenon of pancreatic pseudocysts forming in organs other than the pancreas has not been reported in dogs. This case report and comprehensive human literature review purpose is to raise awareness of this disease process in dogs.

The Connector Domain of Vesicular Stomatitis Virus Large Protein Interacts with the Viral Phosphoprotein.

Vesicular stomatitis virus (VSV) is an archetypical member of Mononegavirales, viruses with a genome of negative-sense single-stranded RNA (-ssRNA). Like other viruses of this order, VSV encodes a unique polymerase, a complex of viral L (large, the enzymatic component) protein and P (phosphoprotein, a cofactor component). The L protein has a modular layout consisting of a ring-shaped core trailed by three accessory domains and requires an N-terminal segment of P (P N-terminal disordered [PNTD]) to perform polymerase activity. To date, a binding site for P on L had not been described. In this report, we show that the connector domain of the L protein, which previously had no assigned function, binds a component of PNTD We further show that this interaction is a positive regulator of viral RNA synthesis, and that the interfaces mediating it are conserved in other members of Mononegavirales Finally, we show that the connector-P interaction fits well into the existing structural information of VSV L.IMPORTANCE This study represents the first functional assignment of the connector domain of a Mononegavirales L protein. Furthermore, this study localizes P polymerase cofactor activity to specific amino acids. The functional necessity of this interaction, combined with the uniqueness of L and P proteins to the order Mononegavirales, makes disruption of the P-connector site a potential target for developing antivirals against other negative-strand RNA viruses. Furthermore, the connector domain as an acceptor site for the P protein represents a new understanding of Mononegavirales L protein biology.

A dual-functional priming-capping loop of rhabdoviral RNA polymerases directs terminal de novo initiation and capping intermediate formation.

The L proteins of rhabdoviruses, such as vesicular stomatitis virus (VSV) and rabies virus (RABV), possess an unconventional mRNA capping enzyme (GDP polyribonucleotidyltransferase, PRNTase) domain with a loop structure protruding into an active site cavity of the RNA-dependent RNA polymerase (RdRp) domain. Here, using complementary VSV and RABV systems, we show that the loop governs RNA synthesis and capping during the dynamic stop-start transcription cycle. A conserved tryptophan residue in the loop was identified as critical for terminal de novo initiation from the genomic promoter to synthesize the leader RNA and virus replication in host cells, but not for internal de novo initiation or elongation from the gene-start sequence for mRNA synthesis or pre-mRNA capping. The co-factor P protein was found to be essential for both terminal and internal initiation. A conserved TxΨ motif adjacent the tryptophan residue in the loop was required for pre-mRNA capping in the step of the covalent enzyme-pRNA intermediate formation, but not for either terminal or internal transcription initiation. These results provide insights into the regulation of stop-start transcription by the interplay between the RdRp active site and the dual-functional priming-capping loop of the PRNTase domain in non-segmented negative strand RNA viruses.

Long-term, open-label extension study of the efficacy and safety of epicutaneous immunotherapy for peanut allergy in children: PEOPLE 3-year results.

BACKGROUND: The PEPITES (Peanut EPIT Efficacy and Safety) trial, a 12-month randomized controlled study of children with peanut allergy and 4 to 11 years old, previously reported the safety and efficacy of epicutaneous immunotherapy (EPIT) for peanut allergy (250 µg, daily epicutaneous peanut protein; DBV712 250 µg). OBJECTIVE: We sought to assess interim safety and efficacy of an additional 2 years of EPIT from the ongoing (5-year treatment) PEOPLE (PEPITES Open-Label Extension) study. METHODS: Subjects who completed PEPITES were offered enrollment in PEOPLE. Following an additional 2 years of daily DBV712 250 µg, subjects who had received DBV712 250 µg in PEPITES underwent month-36 double-blind, placebo-controlled food challenge with an optional month-38 sustained unresponsiveness assessment. RESULTS: Of 213 eligible subjects who had received DBV712 250 µg in PEPITES, 198 (93%) entered PEOPLE, of whom 141 (71%) had assessable double-blind, placebo-controlled food challenge at month 36. At month 36, 51.8% of subjects (73 of 141) reached an eliciting dose of ≥1000 mg, compared with 40.4% (57 of 141) at month 12; 75.9% (107 of 141) demonstrated increased eliciting dose compared with baseline; and 13.5% (19 of 141) tolerated the full double-blind, placebo-controlled food challenge of 5444 mg. Median cumulative reactive dose increased from 144 to 944 mg. Eighteen subjects underwent an optional sustained unresponsiveness assessment; 14 of those (77.8%) maintained an eliciting dose of ≥1000 mg at month 38. Local patch-site skin reactions were common but decreased over time. There was no treatment-related epinephrine use in years 2 or 3. Compliance was high (96.9%), and withdrawals due to treatment-related adverse events were low (1%). CONCLUSIONS: These results demonstrate that daily EPIT treatment for peanut allergy beyond 1 year leads to continued response from a well-tolerated, simple-to-use regimen.

DIFFUSIBLE IODINE-BASED CONTRAST-ENHANCED COMPUTED TOMOGRAPHY AS A NECROPSY AID: A CASE REPORT EVALUATING RESPIRATORY DISEASE IN MACROCEPHALON MALEO.

This study describes the novel use of diffusible iodine-based contrast-enhanced computed tomography (diceCT) as a digital necropsy aid. DiceCT was used postmortem to evaluate the cause of progressive respiratory disease in a juvenile maleo (Macrocephalon maleo). The technique facilitated soft-tissue contrast and a three-dimensional investigation of sinus and choanal anatomy as a means to identify normal and pathologic morphologies. Results showed right-sided narial occlusion by mucoid debris, along with left-sided choanal stenosis caused by osteomyelitis and reactive bone formation. The high spatial resolution afforded by diceCT enabled targeted histology and quantification of the clinical impact of pathologies, which contributed to an effective 60% loss in nasal airway aperture for this individual. This study demonstrates how adding diceCT to traditional necropsy can proffer additional understanding of an individual's pathology, and the resulting data can enhance research programs in vertebrate anatomy, evolution, and health.

Defining HIV-1 Envelope N-Glycan Microdomains through Site-Specific Heterogeneity Profiles.

The HIV-1 envelope (Env) glycans shield the surface of Env from the immune system and form integral interactions important for a functional Env. To understand how individual N-glycosylation sites (NGS) coordinate to form a dynamic shield and evade the immune system through mutations, we tracked 20 NGS in Env from HIV-transmitted/founder (T/F) and immune escape variants and their mutants involving the N262 glycan. NGS were profiled in a site-specific manner using a high-resolution mass spectrometry (MS)-based workflow. Using this site-specific quantitative heterogeneity profiling, we empirically characterized the interdependent NGS of a microdomain in the high-mannose patch (HMP). The changes (shifts) in NGS heterogeneity between the T/F and immune escape variants defined a range of NGS that we further probed for exclusive combinations of sequons in the HMP microdomain using the Los Alamos National Laboratory HIV sequence database. The resultant sequon combinations, including the highly conserved NGS N262, N448, and N301, created an immune escape map of the conserved and variable sequons in the HMP microdomain. This report provides details on how some clustered NGS form microdomains that can be identified and tracked across Env variants. These microdomains have a limited number of N-glycan-sequon combinations that may allow the anticipation of immune escape variants.IMPORTANCE The Env protein of HIV is highly glycosylated, and the sites of glycosylation can change as the virus mutates during immune evasion. Due to these changes, the glycan location and heterogeneity of surrounding N-glycosylation sites can be altered, resulting in exposure of different glycan or proteoglycan surfaces while still producing a viable HIV variant. These changes present a need for vaccine developers to identify Env variants with epitopes most likely to induce durable protective responses. Here we describe a means of anticipating HIV-1 immune evasion by dividing Env into N-glycan microdomains that have a limited number of N-glycan sequon combinations.

Commercial claims costs related to health care resource use associated with a diagnosis of peanut allergy.

BACKGROUND: Peanut allergy (PA) affects approximately 1.6 million US children. The current standard of care is strict avoidance and prompt reaction treatment. Peanut allergy health care costs and health care resource utilization (HCRU) are poorly understood. OBJECTIVE: To estimate PA health care costs and HCRU using a nationally representative commercial payer database. METHODS: The IBM MarketScan Commercial Claims and Encounters Database was examined for PA diagnosis/reaction codes between January 2010 and October 2016 in patients 64 years of age or younger, with age cohort-matched controls. Outcomes were measured 12 months before and after the first claim date. Health care costs and HCRU were compared using Student's t tests and χ2 tests. RESULTS: Patients with a PA-related diagnostic code (n = 41,675) incurred almost double all-cause health care costs vs controls ($6436 vs $3493, P < .001), mainly from inpatient and outpatient medical costs ($5002 vs $2832, P < .001). More than one third of the PA group patients (36%) had a code indicative of an anaphylactic reaction during follow-up. Mean PA or reaction-related code costs per visit totaled $7921 for hospitalizations and $1115 for emergency department (ED) visits. Costs were 30% lower in patients with asthma codes without PA codes vs those with both codes ($5678 vs $8112, P < .001); all-cause ED costs were more than double in patients with atopic dermatitis codes with PA codes vs those without PA codes ($654 vs $308, P < .001). CONCLUSION: National commercial payer claims data indicate a significant health care burden associated with a PA-related code, including over $6400/patient in annual all-cause costs and increased health care utilization.