In Response to Representativeness of U.S. News & World Report Outcome and Volume Measures for Otolaryngology.

Although outcomes account for 45% of the total ranking score in otolaryngology in the 2023-2024 U.S. News Best Hospitals rankings, little attention has been paid to the representativeness of their outcomes or volume analyses. Through retrospective review of finance data from an academic otolaryngology department, we found the overall 2023-2024 USNWR volume estimate accounted for only 10.0% (n = 2, usw 024/20,334) of all adult admissions and outpatient procedures and did not adequately represent the overall case mix or caseload.

Accelerated tumor progression after COVID-19 infection in patients with glioblastoma: A retrospective case-control study.

Background: We observed rapid tumor progression following COVID-19 infection among patients with glioblastoma and sought to systematically characterize their disease course in a retrospective case-control study. Methods: Using an institutional database, we retrospectively identified a series of COVID-19-positive glioblastoma cases and matched them by age and sex 1:2 to glioblastoma controls who had a negative COVID-19 test during their disease course. Demographic and clinical data were analyzed. Hyperprogression was defined using modified response evaluation criteria in solid tumors criteria. Time to progression and overall survival were estimated using the Kaplan-Meier method. Results: Thirty-two glioblastoma cases with positive COVID-19 testing were matched to 64 glioblastoma controls with negative testing; age, sex, and molecular profiles did not differ between groups. Progression events occurred in 27 cases (84%) and 46 controls (72%). Of these, 14 cases (52%) presented with multifocal disease or leptomeningeal disease at progression compared with 10 controls (22%; P = .0082). Hyperprogression was identified in 13 cases (48%) but only 4 controls (9%; P = .0001). Cases had disease progression at a median of 35 days following COVID-19 testing, compared with 164 days for controls (P = .0001). Median survival from COVID-19 testing until death was 8.3 months for cases but 17 months for controls (P = .0016). Median overall survival from glioblastoma diagnosis was 20.7 months for cases and 24.6 months for controls (P = .672). Conclusions: Patients with glioblastoma may have accelerated disease progression in the first 2 months after COVID-19 infection. Infected patients should be monitored vigilantly. Future investigations should explore tumor-immune microenvironment changes linking tumor progression and COVID-19.

Oral Hedgehog Inhibitor, Vismodegib, for Locally Advanced Periorbital and Orbital Basal Cell Carcinoma: A Report by the American Academy of Ophthalmology.

PURPOSE: To review the efficacy and safety of oral vismodegib (Erivedge; Genentech) in the management of locally advanced orbital and periorbital basal cell carcinoma (BCC). METHODS: A literature search was conducted last in September 2023 in the PubMed database for English language original research that evaluated the effect of oral vismodegib on orbital and periorbital BCC. Sixty articles were identified and 16 met the inclusion criteria. RESULTS: Most studies demonstrated high response rates, with up to 100% of patients responding to the medication in individual studies and initial complete regression occurring in up to 88% of patients. Vismodegib treatment resulted in significant reductions in tumor volume, resulting in globe preservation for most patients. However, in 12% of patients, the response was partial. Recurrences also occurred with substantial frequency, even after an initial complete response. As such, up to 79.4% of patients required surgical intervention, and up to 23% of patients still required exenteration. Use of these agents resulted in reductions in tumor volume that may delay or prevent the need for exenteration in some, but not all, patients. Importantly, molecular analysis of tissue excised after vismodegib therapy revealed persistent tumor in all patients, with frequent accumulation of mutations that may confer resistance to further hedgehog inhibitor therapy. Although most adverse events were rated as level I or II, side effects were common, with up to 100% of patients in studies experiencing at least 1 event. Muscle cramps, alopecia, weight loss, fatigue, and dysgeusia were the most common adverse events, and several patients discontinued therapy because of them. Furthermore, 1 patient died of sepsis that may have resulted from the therapy. CONCLUSIONS: Although level I and II evidence are lacking, most studies indicate a benefit from the use of oral vismodegib to treat orbital and periorbital BCC tumor volume. However, patients should be cautioned about the adverse side effects of treatment and the persistence of tumor cells with mutations that may cause long-term resistance. Use of vismodegib as short-term neoadjuvant therapy may be effective in shrinking tumor volume to reduce surgical morbidity while reducing the frequency and severity of side effects. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Staged Excision Technique for Periocular Cutaneous Melanoma: Long-Term Outcomes of the Square Procedure.

PURPOSE: To examine the long-term outcome of the staged excision via the square procedure for the treatment of periocular thin cutaneous melanoma. METHODS: A retrospective chart review of 95 periocular cutaneous melanoma-in-situ and microinvasive melanoma tumors that were treated with the square procedure between April 1, 1994 and December 31, 2018 at the University of Michigan. Demographic and clinical data were evaluated. RESULTS: Of 95 cases, 19 (20%) were atypical junctional melanocytic proliferation with features of early melanoma-in-situ, 63 (66.3%) were melanoma-in-situ and 13 (13.7) were microinvasive melanoma with Breslow depth less than 1 mm. Tumor-free margins were achieved with a median margin of 10 mm (range 5-40 mm). Most cases (68.4%) required multiple excision stages. Surgical revision was necessary in 17.9% of cases and was associated with larger defect size. Local recurrence was noted in 8 patients (8.4%) at a median of 42 months postreconstruction. No tumor characteristics were found to predict recurrence. CONCLUSIONS: The square procedure for periocular melanoma offers an 8.4% recurrence rate, consistent with literature reports on similar staged excision approaches. The staged excision provides an excellent option for comprehensive margin review and tumor control with acceptable cosmetic results after reconstruction.

Intraoperative Image Guidance in Orbital and Lacrimal Surgery: A Report by the American Academy of Ophthalmology.

PURPOSE: To review the efficacy and safety of the use of intraoperative image guidance (IIG) in orbital and lacrimal surgery. METHODS: A literature search of the PubMed database was last conducted in November 2023 for English-language original research that assessed the use of any image guidance system in orbital and lacrimal surgery that included at least 5 patients. The search identified 524 articles; 94 were selected for full-text analysis by the panel. A total of 32 studies met inclusion criteria. The panel methodologist assigned a level II rating to 2 studies and a level III rating to 30 studies. No study met the criteria for level I evidence. RESULTS: Procedures reported on were as follows: fracture repair (n = 14), neoplasm and infiltrate biopsy or excision (n = 6), orbital decompression for Graves ophthalmopathy (n = 3), dacryocystorhinostomy (n = 1), and mixed etiology and procedures (n = 8). Four studies used more than one IIG system. One study that met level II evidence criteria compared the outcomes of orbital fracture repair with IIG (n = 29) and without IIG (n = 29). Borderline better outcomes were reported in the IIG group: 2% versus 10% with diplopia (P = 0.039) and 3% versus 10% with enophthalmos (P = 0.065). The other level II study compared the repair of fractures with navigation (n = 20) and without (n = 20). The group in which navigation was used had a measured mean volume reduction of 3.82 cm3 compared with 3.33 cm3 (P = 0.02), and there was a greater measured reduction in enophthalmos in the navigation group of 0.72 mm (P = 0.001). Although the remaining 30 assessed articles failed to meet level II criteria, all alleged a benefit from IIG. No complications were reported. CONCLUSIONS: A small number of comparative studies suggest that there are improved outcomes when IIG is used in orbital fracture repair, but each study suffers from various limitations. No high-quality comparative studies exist for the management of lacrimal surgery, neoplastic disease, or decompression. Complications attributable to the use of IIG have not been identified, and IIG has not been analyzed for cost savings. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.

Protocol for real-time assessment of mitochondrial and glycolytic ATP production in patient-derived glioma stem-like cells.

Glioma cells switch between energetic pathways to adapt and resist therapies. We present a protocol for measuring mitochondrial and glycolytic ATP rates in patient-derived glioma stem-like cells using a Seahorse XF ATP rate assay. We describe steps for growing 3D glioma stem-like cells, attaching cells to the assay plate, preparing drugs, and running the ATP rate assay. We also detail procedures for imaging viable cell numbers and normalization, with tips to overcome pitfalls in Agilent Seahorse assays.

Supported-amine-catalyzed cascade synthesis of spiro-thiazolone-tetrahydrothiophenes: assessing HSA binding activity.

We have devised a supported-amine-catalyzed efficient synthesis of spiro-thiazolone-tetrahydrothiophenes via a sulfa-Michael/aldol cascade approach. The catalyst demonstrated sustained efficacy over 21 cycles. These derivatives were found to exhibit excellent binding abilities with purified human serum albumin as indicated by both in silico and in vitro-based experiments.

Multidisciplinary Management of Isocitrate Dehydrogenase-Mutated Gliomas in a Contemporary Molecularly Defined Era.

Mutations in isocitrate dehydrogenase (IDH) genes, an early step in the ontogeny of lower-grade gliomas, induce global epigenetic changes characterized by a hypermethylation phenotype and are critical to tumor classification, treatment decision making, and estimation of patient prognosis. The introduction of IDH inhibitors to block the oncogenic neomorphic function of the mutated protein has resulted in new therapeutic options for these patients. To appreciate the implications of these recent IDH inhibitor results, it is important to juxtapose historical outcomes with chemoradiotherapy. Herein, we rationally evaluate recent IDH inhibitor data within historical precedents to guide contemporary decisions regarding the role of observation, maximal safe resection, adjuvant therapies, and the import of patient and tumor variables. The biological underpinnings of the IDH pathway and the mechanisms, impact, and limitations of IDH inhibitors, the actual magnitude of tumor regression and patient benefit, and emergence of resistance pathways are presented to guide future trial development. Management in the current, molecularly defined era will require careful patient selection and risk factor assessment, followed by an open dialog about the results of studies such as INDIGO, as well as mature data from legacy trials, and a discussion about risk-versus-benefit for the choice of treatment, with multidisciplinary decision making as an absolute prerequisite.

Spending, utilization, and coverage for chronic rhinosinusitis with nasal polyposis therapies among Medicare Advantage beneficiaries.

KEY POINTS: CRSwNP-specific mean total annual spending ranged from $5,837 (EDS-FLU) to $28,058 (dupilumab). Most CRSwNP patients receiving biologics had comorbid asthma and did not undergo sinus surgery. While biologics were covered by most Medicare Part D plans, only 37% of plans covered EDS-FLU.

Metagenomic Analysis of Biliary Microbial Flora in Patients with Gallbladder Cancer or Gallstones-Associated Chronic Cholecystitis.

Biliary dysbiosis is associated with gallbladder cancer (GBC). We aimed to look for biliary bacteria specifically detected in GBC patients. We used 16S rRNA-based metagenomic analysis to elucidate biliary microbiota in 30 GBC and 30 gallstones-associated chronic cholecystitis patients. Relative abundance of five genera, Streptococcus, Enterococcus, Halomonas, Escherichia and Caulobacter was significantly associated with GBC. Of 15-species, 7 were detected significantly higher in GBC, Streptococcus anginosus, Streptococcus constellatus, Streptococcus intermedius, Actinomyces bowdenii, Actinomyces israelii, Actinomyces gerencseriae, and Escherichia fergusonii were biosafety level-2 infectious bacteria; other 8 species were biosafety level-1 bacteria. These bacterial species may be involved in pathogenesis of GBC.

Precise Calibration of Femoral Component Rotation Using the Posterior Condylar Axis as a Reference during Image-free Robot-assisted Total Knee Arthroplasty: A Technical Note.

Introduction: The use of image-free robotic systems for total knee arthroplasty (TKA) is gaining popularity. Although the surgical transepicondylar axis (sTEA) is considered the optimal femoral rotational reference during TKA, it is difficult to define intra-operatively. Conventional and image-free robot-assisted TKA (RA-TKA) therefore rely on the use of Whiteside's axis (WSA) or the posterior condylar axis (PCA) as surrogate references. The PCA is considered to be associated with less variability than the WSA. The authors present a simple technique to permit calibration of femoral component rotation (FCR) using the PCA as a reference for image-free robotic systems that do not permit this option. Technique: The image-free robotic systems used by the authors (Navio and CORI, Smith and Nephew, Memphis, TN, USA) permit calibration of FCR only when the perpendicular to WSA is used as a reference. When the PCA is selected as a reference, a fixed 3° of external rotation is set by the robot. The technique proposed by the authors involves the use of the former setting, followed by internal rotation of the perpendicular to the WSA to co-align it with the PCA. The planning menu subsequently permits virtual surgical planning using the PCA as the femoral rotational reference and permits adjustments in rotational positioning of the femoral component while displaying the effect of rotation on bony resection and vice versa in real time. In addition, coaligning the perpendicular to the anatomic trans-epicondylar axis (aTEA) displays the internal rotation of the PCA with respect to the aTEA. This information can be used for setting rotational boundaries with respect to the PCA while using various alternate alignment strategies, like functional alignment, since the relation between the aTEA and sTEA is less likely to be affected by dyplasia and wear when compared with the PCA or WSA. Conclusion: This simple technique permits optimally calibrated rotational positioning of the femoral component during image-free RA-TKA, using the PCA as a reference. It can be applied for optimizing surgery in knees with altered or outlier anatomy, as well as routinely, especially when alternate alignment strategies are used.

Orbital decompression surgery among Medicare beneficiaries in the post-teprotumumab era.

KEY POINTS: Utilization of orbital decompressions (ODS) increased (CAGR: +3.2%) from 2000 to 2019. FDA approved teprotumumab in January 2020; ODS utilization decreased (CAGR: -14.9%) from 2019 to 2022. In 2022, total spending was substantially higher for teprotumumab ($325 million) than surgery ($580,000).

Salvage surgery for recurrent or residual hypopharyngeal squamous cell carcinoma: A systematic review.

BACKGROUND: This systematic review aggregates the data of studies that include site-specific analyses of patients undergoing salvage surgery for residual or recurrent hypopharyngeal squamous cell carcinoma. METHODS: The primary outcomes are disease-free, disease-specific, and overall survival (DFS, DSS, and OS, respectively). Secondary outcomes include complications and postoperative feeding requirements. RESULTS: Fifteen studies met the inclusion criteria with a total of 442 patients. Two-year DFS is reported from 30.0 to 50.0% and 5-year DFS ranges from 15.0 to 57.1%. Five-year DSS ranges from 28.0 to 57.1%. Two-year OS ranges from 38.8 to 52.0% and 5-year OS ranges from 15.5 to 57.1%. Complications include pharyngocutaneous fistula (0.0-71.4%), carotid artery rupture (2.9-13.3%), and stomal stenosis (4.2-20.0%). Complete oral feeding achieved following surgery ranges from 61.9 to 100.0%, while complete gastrostomy tube dependence ranges from 0.0 to 28.6%. CONCLUSIONS: Salvage surgery for residual or recurrent hypopharyngeal squamous cell carcinoma has a relatively high complication rate and should be offered to patients with the understanding of a guarded prognosis.

Imaging HIV-1 Nuclear Import, Uncoating, and Proviral Transcription.

Live-cell imaging has become a powerful tool for dissecting the behavior of viral complexes during HIV-1 infection with high temporal and spatial resolution. Very few HIV-1 particles in a viral population are infectious and successfully complete replication (~1/50). Single-particle live-cell imaging enables the study of these rare infectious viral particles, which cannot be accomplished in biochemical assays that measure the average property of the entire viral population, most of which are not infectious. The timing and location of many events in the early stage of the HIV-1 life cycle, including nuclear import, uncoating, and integration, have only recently been elucidated. Live-cell imaging also provides a valuable approach to study interactions of viral and host factors in distinct cellular compartments and at specific stages of viral replication. Successful live-cell imaging experiments require careful consideration of the fluorescent labeling method used and avoid or minimize its potential impact on normal viral replication and produce misleading results. Ideally, it is beneficial to utilize multiple virus labeling strategies and compare the results to ensure that the virion labeling did not adversely influence the viral replication step that is under investigation. Another potential benefit of using different labeling strategies is that they can provide information about the state of the viral complexes. Here, we describe our methods that utilize multiple fluorescent protein labeling approaches to visualize and quantify important events in the HIV-1 life cycle, including docking HIV-1 particles with the nuclear envelope (NE) and their nuclear import, uncoating, and proviral transcription.

Single-Virion Analysis: A Method to Visualize HIV-1 Particle Content Using Fluorescence Microscopy.

HIV-1 virions incorporate viral RNA, cellular RNAs, and proteins during the assembly process. Some of these components, such as the viral RNA genome and viral proteins, are essential for viral replication, whereas others, such as host innate immune proteins, can inhibit virus replication. Therefore, analyzing the virion content is an integral part of studying HIV-1 replication. Traditionally, virion contents have been examined using biochemical assays, which can provide information on the presence or absence of the molecule of interest but not its distribution in the virion population. Here, we describe a method, single-virion analysis, that directly examines the presence of molecules of interest in individual viral particles using fluorescence microscopy. Thus, this method can detect both the presence and the distribution of molecules of interest in the virion population. Single-virion analysis was first developed to study HIV-1 RNA genome packaging. In this assay, HIV-1 unspliced RNA is labeled with a fluorescently tagged RNA-binding protein (protein A) and some of the Gag proteins are labeled with a different fluorescent protein (protein B). Using fluorescence microscopy, HIV-1 particles can be identified by the fluorescent protein B signal and the presence of unspliced HIV-1 RNA can be identified by the fluorescent protein A signal. Therefore, the proportions of particles that contain unspliced RNA can be determined by the fraction of Gag particles that also have a colocalized RNA signal. By tagging the molecule of interest with fluorescent proteins, single-virion analysis can be easily adapted to study the incorporation of other viral or host cell molecules into particles. Indeed, this method has been adapted to examine the proportion of HIV-1 particles that contain APOBEC3 proteins and the fraction of particles that contain a modified Gag protein. Therefore, single-virion analysis is a flexible method to study the nucleic acid and protein content of HIV-1 particles.

Formation of partially embedded Au nanostructures: Ion beam irradiation on thin film.

The Au partially embedded nanostructure (PEN) is synthesized by ion irradiation on an Au thin film deposited on a glass substrate using a 50 keV Ar ion. Scanning electron microscopy results show ion beam-induced restructuring from irregularly shaped nanostructures (NSs) to spherical Au NSs, and further ion irradiation leads to the formation of well-separated spherical nanoparticles. Higuchi's algorithm of surface analysis is utilized to find the evolution of surface morphology with ion irradiation in terms of the Hurst exponent and fractal dimension. The Au PEN is evidenced by Rutherford backscattering spectrometry and optical studies. Also, the depth of the mechanism behind synthesized PEN is explained on the basis of theoretical simulations, namely, a unified thermal spike and a Monte Carlo simulation consisting of dynamic compositional changes (TRIDYN). Another set of plasmonic NSs was formed on the surface by thermal annealing of the Au film on the substrate. Glucose sensing has been studied on the two types of plasmonic layers: nanoparticles on the surface and PEN. The results reveal the sensing responses of both types of plasmonic layers. However, PEN retains its plasmonic behavior as the NSs are still present after washing with water, which demonstrates the potential for reusability. RESEARCH HIGHLIGHTS: Synthesis of PENs by ion irradiation Utilization of Higuchi's algorithm to explore the surface morphology. Unified thermal spike and TRIDYN simulations being used to explain the results. Glucose is only used as a test case for reusability of substrate.

Medical Management of Headache and Facial Pain in CRS: A Systematic Review and Meta-Analysis.

OBJECTIVES: This study aims to characterize the effect of medical therapy on headache and facial pain/pressure among patients with chronic rhinosinusitis (CRS). DATA SOURCES: CINAHL, PubMed, and Scopus. METHODS: CINAHL, PubMed, and Scopus were searched from inception through April 10th, 2024, for English language articles reporting headache or facial pain/pressure outcomes in CRS patients. Inclusion was restricted to studies reporting results of the medical treatment of CRS in nonsurgical cohorts. Primary outcome measures included the sino-nasal outcome test (SNOT) and the visual analogue scale (VAS). Meta-analyses of continuous measures (mean), mean difference (Δ), and proportions (%) were conducted. RESULTS: The initial search yielded 2429 unique articles. After a full-text review of 272 articles, 17 studies reporting outcomes for 2269 patients were included in the meta-analysis. The mean patient age was 48.6 years (range 18.0-86.0; 95% CI: 46.5 to 50.6), among which 55.4% (95% CI: 51.5 to 59.4) were male and 82.9% (95% CI: 68.8 to 93.4) had nasal polyposis. SNOT facial pain/pressure scores improved by 1.1 points (95% CI: -1.7 to -0.5; relative reduction 40.4%) with non-biologic therapies and 1.0 point (95% CI: -1.4 to -0.6; relative reduction 54.6%) with biologic therapies. On an 11-point scale, VAS headaches scores improved by 1.8 units (95% CI: -3.3 to -0.3; 42.1% relative reduction) in CRSwNP patients and 1.0 unit (95% CI: -1.7 to -0.3; 54.0% relative reduction) in CRSsNP patients. CONCLUSIONS: Our findings suggest medical therapy significantly reduces facial pain and pressure in the CRS population. Laryngoscope, 2024.

Surgical management of headache and facial pain/pressure in chronic rhinosinusitis: A systematic review and meta-analysis.

BACKGROUND: Headache and facial pain are common symptoms of chronic rhinosinusitis (CRS). However, given the numerous etiologies that can cause these symptoms, the impact of sinus surgery is not well characterized. METHODS: A systematic review was performed by searching the literature from inception through June 6, 2023. English-language articles reporting outcomes for facial pain/pressure or headache following endoscopic sinus surgery were selected for inclusion. Meta-analyses were performed using random and fixed effect models on continuous measures (mean), mean difference (Δ), and proportions (%). RESULTS: A total of 26 articles reporting on 2839 patients were selected for inclusion. The mean patient age was 44.0 ± 3.9 (range 16.0-84.0), with an average symptom duration of 5.3 ± 2.8 years. Among these patients, 56.5% (95% confidence interval [CI]: 52.3-60.6) were male and 77.0% (95% CI: 56.6-92.3) had nasal polyposis (NP). Patients with and without NP reported substantial reductions in both 22-item sino-nasal outcome test facial pain/pressure (with NP: -1.4 [95% CI: -1.6 to -1.2; relative reduction 59.1%]; without NP: -1.5 [95% CI: -1.9 to -1.1; relative reduction 60.9%]) and visual analogue scale (VAS) headache (with NP: -2.5 [95% CI: -2.8 to -2.1; relative reduction 67.2%]; without NP: -2.8 [95% CI: -4.7 to -1.0; relative reduction 42.7%]). Symptom reductions were greater in the without NP versus with NP group; VAS facial pain/pressure: Δ0.4 (95% CI: 0.2-0.6; p = 0.0006) and VAS headache: Δ0.4 (95% CI: 0.1-0.7; p = 0.02). CONCLUSIONS: Our findings suggest that CRS patients, regardless of polyp status, benefit from significant reductions in facial pain/pressure and headache following surgical therapy.

Topical steroids for chronic rhinosinusitis without nasal polyps: A systematic review and meta-analysis.

BACKGROUND: Evidence supporting topical steroids for the treatment of chronic rhinosinusitis without nasal polyposis (CRSsNP) is unclear. Recent trials describe alternative topical steroid delivery modalities, including rinses and exhalation delivery system (EDS), necessitating a re-examination of the current literature. METHODS: Cochrane Library, CINAHL, PubMed, and Scopus databases were searched from inception to February 13, 2024 for placebo-controlled randomized control trials on topical steroids used to treat CRSsNP, including topical spray, nasal irrigation, sinonasal catheter, and EDS modalities. Primary outcome measures included total symptom scores (TSS) (Δ) and response rates (odds ratio). RESULTS: Ten trials (N = 751) were included for meta-analysis, with a mean age of 47.5 years (range: 18-80 years; 95% confidence interval [CI]: 43.9-51.2 years). Topical steroids delivered by any method significantly improved TSS in CRSsNP patients (Δ0.4; 95% CI: 0.3-0.6; p < 0.0001). When stratified by allergy status, CRSsNP patients without allergy had significantly improved TSS when treated with EDS (Δ0.4; 95% CI: 0.1-0.7; p = 0.01), but not with topical spray (Δ0.04; 95% CI: -0.9 to 1.0; p = 0.94). Patients treated with EDS or sinonasal catheter responded significantly better compared to placebo (odds ratio [OR]: 3.4; 95% CI: 1.9-6.0; p < 0.0001; OR: 12.4; 95% CI: 1.8-83.8; p < 0.01), whereas patients treated with topical spray had no significant difference (OR: 1.8; 95% CI: 0.9-4.0; p = 0.12). CONCLUSIONS: Topical steroids are effective in treating CRSsNP, especially when delivered via EDS or sinonasal catheter. Future trials comparing steroid delivery mechanisms using validated outcome measures in CRSsNP populations are needed.

Structural insights into PPP2R5A degradation by HIV-1 Vif.

HIV-1 Vif recruits host cullin-RING-E3 ubiquitin ligase and CBFß to degrade the cellular APOBEC3 antiviral proteins through diverse interactions. Recent evidence has shown that Vif also degrades the regulatory subunits PPP2R5(A-E) of cellular protein phosphatase 2A to induce G2/M cell cycle arrest. As PPP2R5 proteins bear no functional or structural resemblance to A3s, it is unclear how Vif can recognize different sets of proteins. Here we report the cryogenic-electron microscopy structure of PPP2R5A in complex with HIV-1 Vif-CBFß-elongin B-elongin C at 3.58 Å resolution. The structure shows PPP2R5A binds across the Vif molecule, with biochemical and cellular studies confirming a distinct Vif-PPP2R5A interface that partially overlaps with those for A3s. Vif also blocks a canonical PPP2R5A substrate-binding site, indicating that it suppresses the phosphatase activities through both degradation-dependent and degradation-independent mechanisms. Our work identifies critical Vif motifs regulating the recognition of diverse A3 and PPP2R5A substrates, whereby disruption of these host-virus protein interactions could serve as potential targets for HIV-1 therapeutics.