Type I Phosphatidylinositol-4-Phosphate 5-Kinases α and γ Play a Key Role in Targeting HIV-1 Pr55Gag to the Plasma Membrane.

HIV-1 assembly occurs principally at the plasma membrane (PM) of infected cells. Gag polyprotein precursors (Pr55Gag) are targeted to the PM, and their binding is mediated by the interaction of myristoylated matrix domain and a PM-specific phosphoinositide, the phosphatidylinositol-(4,5)-bisphosphate [PI(4,5)P2]. The major synthesis pathway of PI(4,5)P2 involves the activity of phosphatidylinositol-4-phosphate 5-kinase family type 1 composed of three isoforms (PIP5K1α, PIP5K1ß, and PIP5K1γ). To examine whether the activity of a specific PIP5K1 isoform determines proper Pr55Gag localization at the PM, we compared the cellular behavior of Pr55Gag in the context of PIP5K1 inhibition using siRNAs that individually targeted each of the three isoforms in TZM-bl HeLa cells. We found that downregulation of PIP5K1α and PIP5K1γ strongly impaired the targeting of Pr55Gag to the PM with a rerouting of the polyprotein within intracellular compartments. The efficiency of Pr55Gag release was thus impaired through the silencing of these two isoforms, while PIP5K1ß is dispensable for Pr55Gag targeting to the PM. The PM mistargeting due to the silencing of PIP5K1α leads to Pr55Gag hydrolysis through lysosome and proteasome pathways, while the silencing of PIP5K1γ leads to Pr55Gag accumulation in late endosomes. Our findings demonstrated that, within the PIP5K1 family, only the PI(4,5)P2 pools produced by PIP5K1α and PIP5K1γ are involved in the Pr55Gag PM targeting process.IMPORTANCE PM specificity of Pr55Gag membrane binding is mediated through the interaction of PI(4,5)P2 with the matrix (MA) basic residues. It was shown that overexpression of a PI(4,5)P2-depleting enzyme strongly impaired PM localization of Pr55Gag However, cellular factors that control PI(4,5)P2 production required for Pr55Gag-PM targeting have not yet been characterized. In this study, by individually inhibiting PIP5K1 isoforms, we elucidated a correlation between PI(4,5)P2 metabolism pathways mediated by PIP5K1 isoforms and the targeting of Pr55Gag to the PM of TZM-bl HeLa cells. Confocal microscopy analyses of cells depleted from PIP5K1α and PIP5K1γ show a rerouting of Pr55Gag to various intracellular compartments. Notably, Pr55Gag is degraded by the proteasome and/or by the lysosomes in PIP5K1α-depleted cells, while Pr55Gag is targeted to endosomal vesicles in PIP5K1γ-depleted cells. Thus, our results highlight, for the first time, the roles of PIP5K1α and PIP5K1γ as determinants of Pr55Gag targeting to the PM.

Synthesis and Antiviral Evaluation of (1,4-Disubstituted-1,2,3-Triazol)-(E)-2-Methyl-but-2-Enyl Nucleoside Phosphonate Prodrugs.

A series of hitherto unknown (1,4-disubstituted-1,2,3-triazol)-(E)-2-methyl-but-2-enyl nucleosides phosphonate prodrugs bearing 4-substituted-1,2,3-triazoles were prepared in a straight approach through an olefin acyclic cross metathesis as the key synthetic step. All novel compounds were evaluated for their antiviral activities against HBV, HIV and SARS-CoV-2. Among these molecules, only compound 15j, a hexadecyloxypropyl (HDP)/(isopropyloxycarbonyl-oxymethyl)-ester (POC) prodrug, showed activity against HBV in Huh7 cell cultures with 62% inhibition at 10 µM, without significant cytotoxicity (IC50 = 66.4 µM in HepG2 cells, IC50 = 43.1 µM in HepG2 cells) at 10 µM.

IFITM proteins are incorporated onto HIV-1 virion particles and negatively imprint their infectivity.

BACKGROUND: Interferon induced transmembrane proteins 1, 2 and 3 (IFITMs) belong to a family of highly related antiviral factors that have been shown to interfere with a large spectrum of viruses including Filoviruses, Coronaviruses, Influenza virus, Dengue virus and HIV-1. In all these cases, the reported mechanism of antiviral inhibition indicates that the pool of IFITM proteins present in target cells blocks incoming viral particles in endosomal vesicles where they are subsequently degraded. RESULTS: In this study, we describe an additional mechanism through which IFITMs block HIV-1. In virus-producing cells, IFITMs coalesce with forming virions and are incorporated into viral particles. Expression of IFITMs during virion assembly leads to the production of virion particles of decreased infectivity that are mostly affected during entry in target cells. This mechanism of inhibition is exerted against different retroviruses and does not seem to be dependent on the type of Envelope present on retroviral particles. CONCLUSIONS: The results described here identify a novel mechanism through which IFITMs affect HIV-1 infectivity during the late phases of the viral life cycle. Put in the context of data obtained by other laboratories, these results indicate that IFITMs can target HIV at two distinct moments of its life cycle, in target cells as well as in virus-producing cells. These results raise the possibility that IFITMs could similarly affect distinct steps of the life cycle of a number of other viruses.

Characteristics of patients recently infected with HIV-1 non-B subtypes in France: a nested study within the mandatory notification system for new HIV diagnoses.

The presence of HIV-1 non-B subtypes in Western Europe is commonly attributed to migration of individuals from non-European countries, but the possible role of domestic infections with non-B subtypes is not well investigated. The French mandatory anonymous reporting system for HIV is linked to a virological surveillance using assays for recent infection (<6 months) and serotyping. During the first semester of years 2007 to 2010, any sample corresponding to a non-B recent infection was analyzed by sequencing a 415-bp env region, followed by phylogenetic analysis and search for transmission clusters. Two hundred thirty-three recent HIV-1 infections with non-B variants were identified. They involved 5 subtypes and 7 circulating recombinant forms (CRFs). Ninety-two cases (39.5%) were due to heterosexual transmissions, of which 39 occurred in patients born in France. Eighty-five cases (36.5%) were identified in men having sex with men (MSM). Forty-three recent non-B infections (18.5%) segregated into 14 clusters, MSM being involved in 11 of them. Clustered transmission events included 2 to 7 cases per cluster. The largest cluster involved MSM infected by a CRF02_AG variant. In conclusion, we found that the spread of non-B subtypes in France occurs in individuals of French origin and that MSM are particularly involved in this dynamic.

Sequence and functional analysis of the envelope glycoproteins of hepatitis C virus variants selectively transmitted to a new host.

Hepatitis C virus (HCV) remains a challenging public health problem worldwide. The identification of viral variants establishing de novo infections and definition of the phenotypic requirements for transmission would facilitate the design of preventive strategies. We explored the transmission of HCV variants in three cases of acute hepatitis following needlestick accidents. We used single-genome amplification of glycoprotein E1E2 gene sequences to map the genetic bottleneck upon transmission accurately. We found that infection was likely established by a single variant in two cases and six variants in the third case. Studies of donor samples showed that the transmitted variant E1E2 amino acid sequences were identical or closely related to those of variants from the donor virus populations. The transmitted variants harbored a common signature site at position 394, within hypervariable region 1 of E2, together with additional signature amino acids specific to each transmission pair. Surprisingly, these E1E2 variants conferred no greater capacity for entry than the E1E2 derived from nontransmitted variants in lentiviral pseudoparticle assays. Mutants escaping the antibodies of donor sera did not predominate among the transmitted variants either. The fitness parameters affecting the selective outgrowth of HCV variants after transmission in an immunocompetent host may thus be more complex than those suggested by mouse models. Human antibodies directed against HCV envelope effectively cross-neutralized the lentiviral particles bearing E1E2 derived from transmitted variants. These findings provide insight into the molecular mechanisms underlying HCV transmission and suggest that viral entry is a potential target for the prevention of HCV infection.

Sequential biogenesis of host cell membrane rearrangements induced by hepatitis C virus infection.

Like most positive-strand RNA viruses, hepatitis C virus (HCV) forms a membrane-associated replication complex consisting of replicating RNA, viral and host proteins anchored to altered cell membranes. We used a combination of qualitative and quantitative electron microscopy (EM), immuno-EM, and the 3D reconstruction of serial EM sections to analyze the host cell membrane alterations induced by HCV. Three different types of membrane alteration were observed: vesicles in clusters (ViCs), contiguous vesicles (CVs), and double-membrane vesicles (DMVs). The main ultrastructural change observed early in infection was the formation of a network of CVs surrounding the lipid droplets. Later stages in the infectious cycle were characterized by a large increase in the number of DMVs, which may be derived from the CVs. These DMVs are thought to constitute the membranous structures harboring the viral replication complexes in which viral replication is firmly and permanently established and to protect the virus against double-stranded RNA-triggered host antiviral responses.

A further investigation regarding the efficacy of and preference for positive and corrective feedback.

Although feedback is a widely used intervention for improving performance, it is unclear what characteristics individuals prefer and what is necessary for it to be effective. The purpose of this study was to systematically extend Simonian and Brand (2022) by addressing the limitations of the study and adding a best-treatment phase. During an acquisition phase, participants received either positive, corrective, or no feedback upon task completion. Nine of 10 participants mastered the task that was associated with corrective feedback, and one participant mastered the task with no feedback. Eight participants completed a preference phase in which they were provided a choice of either positive or corrective feedback when learning to play a novel game. Half of the eight participants showed a preference for corrective feedback, and the remaining participants had mixed preferences. Overall, corrective feedback was more efficacious and more preferred than positive feedback.

Relevance of Tacrolimus Trough Concentration and Hepatitis E virus Genetic Changes in Kidney Transplant Recipients With Chronic Hepatitis E.

Introduction: Hepatitis E virus (HEV) can cause chronic infection (≥3 months) and cirrhosis in immunocompromised patients, especially kidney transplant recipients. Low alanine aminotransferase (ALT) levels and high HEV intrahost diversity have previously been associated with evolution toward chronicity in these patients. We hypothesized that additional clinical and viral factors could be associated with the risk of chronic HEV infection. Methods: We investigated a series of 27 kidney transplant recipients with HEV infection, including 20 patients with chronic hepatitis E. Results: High tacrolimus trough concentration at diagnosis was the most relevant marker associated with chronic hepatitis E (9.2 vs. 6.4 ng/ml, P = 0.04). Most HEV genetic changes selected during HEV infection were compartmentalized between plasma and feces. Conclusion: This compartmentalization highlights the diversity and complexity of HEV replication compartments. Tacrolimus trough concentration at diagnosis of HEV infection could allow an early identification of patients at high risk of chronic hepatitis E and guide treatment initiation.

HIV cell-to-cell transmission requires the production of infectious virus particles and does not proceed through env-mediated fusion pores.

Direct cell-to-cell transmission of human immunodeficiency virus (HIV) is a more potent and efficient means of virus propagation than infection by cell-free virus particles. The aim of this study was to determine whether cell-to-cell transmission requires the assembly of enveloped virus particles or whether nucleic acids with replication potential could translocate directly from donor to target cells through envelope glycoprotein (Env)-induced fusion pores. To this end, we characterized the transmission properties of viruses carrying mutations in the matrix protein (MA) that affect the incorporation of Env into virus particles but do not interfere with Env-mediated cell-cell fusion. By use of cell-free virus, the infectivity of MA mutant viruses was below the detection threshold both in single-cycle and in multiple-cycle assays. Truncation of the cytoplasmic tail (CT) of Env restored the incorporation of Env into MA mutant viruses and rescued their cell-free infectivity to different extents. In cell-to-cell transmission assays, MA mutations prevented HIV transmission from donor to target cells, despite efficient Env-dependent membrane fusion. HIV transmission was blocked at the level of virus core translocation into the cytosol of target cells. As in cell-free assays, rescue of Env incorporation by truncation of the Env CT restored the virus core translocation and cell-to-cell infectivity of MA mutant viruses. These data show that HIV cell-to-cell transmission requires the assembly of enveloped virus particles. The increased efficiency of this infection route may thus be attributed to the high local concentrations of virus particles at sites of cellular contacts rather than to a qualitatively different transmission process.

Procedural parameters in equivalence-based instruction with individuals diagnosed with autism: A call for systematic research.

Equivalence-based instruction (EBI) is an efficient and efficacious methodology to establish equivalence classes that has been used to teach various academic skills to neurotypical adults. Although previous reviews confirmed the utility of EBI with participants with developmental disabilities, it is unclear whether certain procedural parameters are associated with positive equivalence outcomes. We extended previous reviews by categorizing studies that used EBI with individuals diagnosed with autism spectrum disorder and assessed whether any procedural parameters were associated with better equivalence responding. Due to the wide variability of procedural parameters in EBI research, the best procedural permutations to form equivalence classes with individuals diagnosed with autism spectrum disorder are still unknown. Thus, this paper serves as a call to action for applied researchers. Specifically, we encourage and invite researchers to systematically investigate the necessary variables or combination of variables that may lead to successful equivalence class formation.

On a persisting curious double standard in behavior analysis: Behavioral scholars' perspectives on procedural fidelity.

Procedural fidelity is the extent to which independent variables are implemented as designed. Despite 40 years of discussion about the importance of procedural fidelity for behavioral research, reporting of fidelity data remains an uncommon practice in behavior-analytic journals. Researchers have speculated about reasons for underreporting, but the perspectives of scholars about when reporting is warranted or necessary have not yet been explored. Thus, the purpose of this study was to evaluate possible reasons for infrequent reporting of fidelity data in behavior-analytic studies. To address this purpose, we conducted focus groups with scholars in applied behavior analysis. Five themes emerged regarding why procedural fidelity data are not typically reported. We provide a discussion about how these themes are interrelated and offer suggestions and recommendations to assist with the collection and reporting of fidelity data.

The Performance Diagnostic Checklist-Human Services (1.1): An initial assessment of validity and reliability.

The Performance Diagnostic Checklist-Human Services (PDC-HS) is an assessment used to identify variables contributing to staff performance concerns in human-service settings. In the current study, we introduce and assess the test validity, interrater reliability, and test-retest reliability of the PDC-HS (1.1), a revised version of the assessment that included revised instructions, questions, and intervention planning references. We measured the psychometric properties of the revised assessment by analyzing answers obtained from watching video vignettes of simulated interviews between consultants and a supervisor. Twenty-one participants watched the vignettes and completed the PDC-HS (1.1) based on the answers provided during the interview. We also included an item analysis to identify questions on which participants made errors and an intervention selection task to assess whether participants selected an appropriate intervention to target the indicated domain. The results support the use of the PDC-HS (1.1) in human services settings.

A detailed examination of reporting procedural fidelity in the Journal of Applied Behavior Analysis.

Few reviews on procedural fidelity-the degree to which procedures are implemented as designed-provide details to gauge the quality of fidelity reporting in behavior-analytic research. This review focused on experiments in the Journal of Applied Behavior Analysis (2006-2021) with "integrity" or "fidelity" in the abstract or body. When fidelity data were collected, the coders characterized measurement details (e.g., description of calculation, report of single or multiple values, frequency of fidelity checks, checklist use). The researchers found increasing trends in describing the calculation(s), reporting multiple values, and stating the frequency of measurement. Few studies described using a checklist. Most studies reported fidelity as a percentage, with high obtained values (M = 97%). When not collecting fidelity data was stated as a limitation, authors were unlikely to provide a rationale for the omission. We discuss recommendations for reporting procedural fidelity to increase the quality of and transparency in behavior-analytic research.

A parametric analysis of procedural fidelity errors following mastery of a task: A translational study.

Procedural fidelity is defined as the extent to which the independent variable is implemented as prescribed. Research using computerized tasks has shown that fidelity errors involving consequences for behavior can hinder skill acquisition. However, studies examining the effects of these errors once skills have been mastered are lacking. Thus, this translational study investigated the effects of varying levels of fidelity following mastery of a computerized arbitrary matching-to-sample task. A group design (consisting of five groups) was used in which college students initially completed 250 trials during which no programmed errors (i.e., perfect fidelity) were arranged, followed by an additional 250 trials with consequences delivered across various levels of fidelity (i.e., 20, 40, 60, 80, and 100% of trials administered without errors). The results showed that participants assigned to higher fidelity conditions performed better (on average). These results extended the findings of previous studies by demonstrating how errors involving consequences affect behavior across various stages of learning.

Trends in Reporting Procedural Integrity: A Comparison.

Procedural integrity refers to the extent to which an independent variable is implemented as described. Measuring procedural integrity is one important factor when considering internal and external validity of experiments. Experimental articles in behavior-analytic journals have rarely reported procedural-integrity data. The purpose of this study was to update previous reviews of whether articles published in the Journal of Applied Behavior Analysis reported procedural integrity, spanning a period from 1980 to 2020, and compare reporting in JABA to recent reviews of studies published in Behavior Analysis in Practice (2008-2019) and the Journal of Organizational Behavior Management (2000-2020). Procedural integrity continues to be underreported across all three journals, but an increasing trend in reporting procedural integrity is evident in the Journal of Applied Behavior Analysis and Behavior Analysis in Practice. In addition to our recommendations and implications for research and practice, we provide examples and resources to assist researchers and practitioners with recording and reporting integrity data.

A pig model of chronic hepatitis E displaying persistent viremia and a downregulation of innate immune responses in the liver.

BACKGROUND: Hepatitis E virus (HEV) is a zoonotic virus transmitted by pig meat and responsible for chronic hepatitis E in immunocompromised patients. It has proved challenging to reproduce this disease in its natural reservoir. We therefore aimed to develop a pig model of chronic hepatitis E to improve the characterization of this disease. METHODS: Ten pigs were treated with a tacrolimus-based regimen and intravenously inoculated with HEV. Tacrolimus trough concentration, HEV viremia, viral diversity, innate immune responses, liver histology, clinical disease and biochemical markers were monitored for 11 weeks post-infection (p.i.). RESULTS: HEV viremia persisted for 11 weeks p.i. HEV RNA was detected in the liver, small intestine, and colon at necropsy. Histological analysis revealed liver inflammation and fibrosis. Several mutations selected in the HEV genome were associated with compartmentalization in the feces and intestinal tissues, consistent with the hypothesis of extrahepatic replication in the digestive tract. Antiviral responses were characterized by a downregulation of IFN pathways in the liver, despite an upregulation of RIG-I and ISGs in the blood and liver. CONCLUSIONS: We developed a pig model of chronic hepatitis E that reproduced the major hallmarks of this disease. This model revealed a compartmentalization of HEV genomes in the digestive tract and a downregulation of innate immune responses in the liver. These original features highlight the relevance of our model for studies of the pathogenesis of chronic hepatitis E and for validating future treatments.

Continuous spread of HIV-1 subtypes D and CRF01_AE in France from 2003 to 2009.

Among 61 and 35 patients who were infected in France by viruses of the rare clades D and CRF01_AE, respectively, approximately half of them originated from areas where HIV-1 is endemic, but the data showed that both clades have spread in the French indigenous population, particularly in men having sex with men (MSM).

Assessing the efficacy of and preference for positive and corrective feedback.

Feedback is an effective strategy for improving performance and consists of multiple characteristics. One characteristic that can influence feedback efficacy is its nature (whether feedback is positive or corrective) and little is known about the conditions under which individuals may prefer corrective over positive feedback. Thus, the purpose of this study was to assess the efficacy of and preference for positive and corrective feedback during the acquisition of novel tasks. In the first phase, participants received either positive, corrective, or no feedback across three novel tasks. Participants only mastered the task in which they received corrective feedback. In the second phase, participants chose to receive either positive or corrective feedback after completing trials of the previous phase's control task. All participants chose to receive corrective feedback more frequently than positive feedback. We discuss the implications of the results for feedback delivery in the workplace and provide suggestions for future research.

The Performance Diagnostic Checklist - Human Services: Guidance for Assessment Administration.

The Performance Diagnostic Checklist - Human Services (PDC-HS) is an assessment designed to assess the environmental variables contributing to employee performance concerns in human-service settings. Recent research has demonstrated that interventions indicated by the PDC-HS result in improved employee performance across several human-service settings and that the assessment has acceptable reliability and validity. Although PDC-HS-indicated interventions have been effective at increasing employee performance, there is a need for additional guidance when using the assessment given the limited nature of the original administration guidelines. Thus, the purpose of the current manuscript is to introduce additional guidance for use of the PDC-HS across a variety of situations.

Treatment Integrity Reporting in Behavior Analysis in Practice 2008-2019.

Treatment integrity is the extent to which procedures are implemented in a manner consistent with their prescribed protocols and is necessary for reaching accurate conclusions regarding functional relations between dependent (i.e., behavior) and independent (i.e., the environment) variables. Several studies assessing the frequency that studies report treatment integrity have been conducted. However, no review has included articles from Behavior Analysis in Practice. Thus, the current study reviewed Behavior Analysis in Practice between 2008 and 2019 to assess the frequency of studies reporting treatment integrity data. A total of 193 articles consisting of 205 studies met the inclusionary criteria for this review. Ninety-six studies (46.83%) reported treatment integrity data, compared to 193 (94.15%) that provided interobserver agreement data. Additionally, 98 studies (47.80%) were considered high risk for treatment implementation inaccuracies. Recommendations and implications for research and practice are discussed.