Complete Genome of Achromobacter xylosoxidans, a Nitrogen-Fixing Bacteria from the Rhizosphere of Cowpea (Vigna unguiculata [L.] Walp) Tolerant to Cucumber Mosaic Virus Infection.

Achromobacter xylosoxidans is one of the nitrogen-fixing bacteria associated with cowpea rhizosphere across Africa. Although its role in improving soil fertility and inducing systemic resistance in plants against pathogens has been documented, there is limited information on its complete genomic characteristics from cowpea roots. Here, we report the complete genome sequence of A. xylosoxidans strain DDA01 isolated from the topsoil of a field where cowpea plants tolerant to cucumber mosaic virus (CMV) were grown in Ibadan, Nigeria. The genome of DDA01 was sequenced via Illumina MiSeq and contained 6,930,067 nucleotides with 67.55% G + C content, 73 RNAs, 59 tRNAs, and 6421 protein-coding genes, including those associated with nitrogen fixation, phosphate solubilization, Indole3-acetic acid production, and siderophore activity. Eleven genetic clusters for secondary metabolites, including alcaligin, were identified. The potential of DDA01 as a plant growth-promoting bacteria with genetic capabilities to enhance soil fertility for resilience against CMV infection in cowpea is discussed. To our knowledge, this is the first complete genome of diazotrophic bacteria obtained from cowpea rhizosphere in sub-Saharan Africa, with potential implications for improved soil fertility, plant disease resistance, and food security.

Revision Surgery after Single Level Anterior Cervical Discectomy and Fusion With Plate vs Stand-Alone Cage over 2 to 5 Year Follow-Up.

STUDY DESIGN: retrospective study. OBJECTIVE: To investigate the incidence of all-cause revision surgery between plated vs stand-alone cage constructs for single level ACDF. METHODS: We retrospectively analyzed a commercial insurance claims database. Patients 18-65 years-old were included if they underwent single-level inpatient ACDF (defined with CPT codes) from 2010 - 2018, with a minimum of 2-year continuous insurance enrollment. The primary independent variable was the use of anterior plating vs zero profile device or stand-alone cage. Synthetic (ie, metal, PEEK, etc.) vs allograft interbody was a secondary independent variable. The primary outcome variable was revision cervical arthrodesis after the index operation. RESULTS: In total, 21092 patients undergoing single-level inpatient ACDF were included. 10.0% received a stand-alone cage during the index operation. Mean follow-up duration was 4.5 years. Revision arthrodesis occurred in 8.2% of patients overall, at a mean of 2.4 years after the index surgery. Patients with anterior plating had a lower rate of all-cause revision surgery in unadjusted (overall rate 8.1% vs 9.6%, P = 0.0185) and adjusted analysis (OR 0.78, P = 0.0016) vs stand-alone cages. Patients with stand-alone cages had higher rates of revision with a posterior approach than did patients with plated constructs. In sub-analysis, the combination of a stand-alone interbody device with an allograft had significantly higher odds of revision than other combinations of devices. CONCLUSION: Among commercially insured patients ≤65 years-old undergoing single-level ACDF, anterior plating was associated with a reduced incidence of revision surgery compared to stand-alone cages within the follow up period of our study.

A Decade of Chronic Norovirus Infection Surveillance at the NIH Clinical Research Center: Clinical Characteristics, Molecular Epidemiology, and Replication.

BACKGROUND: Noroviruses are an important viral cause of chronic diarrhea in immunocompromised individuals. METHOD: We collected norovirus-positive stool samples (n=448) from immunocompromised patients (n=88) at the National Institutes of Health Clinical Research Center, U.S. from 2010-2022. We assessed clinical characteristics of the cohort, norovirus molecular epidemiology, and infectivity of norovirus specimens in human intestinal enteroids (HIEs) monolayers. RESULTS: Thirty-nine of the 88 patients had sequential stool samples that allowed documentation of chronic norovirus infection with shedding levels ranging from 104 to 1011 genome copies/g of stool. The majority with confirmed chronic norovirus infection in this cohort (32/39, 82%) had clinical evidence of an inborn error of immunity (13 identified monogenic diseases), most with combined immunodeficiency (15 of 32) or common variable immunodeficiency (11 of 32). Noroviruses detected in the cohort were genetically diverse: both Genogroup I (GI.2, GI.3, GI.5, and GI.6) and Genogroup II (GII.1-GII.4, GII.6, GII.7, GII.12, GII.14, and GII.17) genotypes were detected, with GII.4 variants (Osaka, Apeldoorn, Den Haag, New Orleans, and Sydney) predominant (51 of 88, 57.9%). Viruses belonging to the GII.4 Sydney variant group that replicated in HIEs (n=9) showed a higher fold-increase in RNA genome copies during infection compared to others that replicated. CONCLUSIONS: Genetically and biologically diverse noroviruses established chronic infection in individuals with both inborn and acquired immunologic defects enrolled in an NIH surveillance study spanning 12 years, demonstrating the unique nature of each virus and host interaction.

Cultivation of Limnospira maxima under extreme environmental conditions in Saudi Arabia: Salinity adaptation and scaling-up from laboratory culture to large-scale production.

Limnospira maxima has been adapted to grow in high salinity and in an economically alternative medium using industrial-grade fertilizers under harsh environmental conditions in Saudi Arabia. A sequence of scaling-up processes, from the laboratory to large-scale open raceways, was conducted along with gradual adaptation to environmental stress (salinity, light, temperature, pH). High biomass concentration at harvest point and areal productivity were achieved during the harsh summer season (1.122 g L-1 and 60.35 g m-2 day-1, respectively). The average protein content was found to be above 40 % of dry weight. Changes in the color and morphological appearance of the L. maxima culture were observed after direct exposure to sunlight in the outdoor raceways. These results demonstrate a successful and robust adaptation method for algal cultivation at outdoor large-scale in harsh environment (desert conditions) and also prove the feasibility of using hypersaline seawater (42 g kg-1) as an algal growth medium.

Sports and Recreation-Related Wrist Fractures: An Epidemiological Study.

Background Wrist fractures have increased over the past several decades. The objective of this study was to identify all-cause and sports-related incidence rates of wrist fractures presenting to emergency departments (EDs) in the United States (U.S.) from 2013 to 2022. A secondary aim of the study was to identify if wrist fractures significantly decreased during 2020. Methodology The National Electronic Injury Surveillance System database was queried to identify the number of wrist fractures presenting to U.S. EDs from 2013 to 2022. Incidence rates in 100,000 person-years were calculated by sport, age, sex, and year. Results From 2013 to 2022, there were 2,027,131 wrist fractures evaluated at U.S. EDs. Injuries peaked in the 10-14-year-old age group, followed by the 5-9 and 85+-year-old age groups. In total, 1,096,598 were sustained during sports and recreation. Cycling, playgrounds, and skateboarding were the leading sports and recreation-related activities. Sports-related wrist fractures followed a unimodal distribution peaking in the 10-14-year-old age group. Females sustained 52% of wrist fractures overall but only 39% of sports-related wrist fractures. All-terrain vehicle and skateboarding-related wrist fractures significantly increased over the study period. Playground and soccer-related wrist fractures significantly decreased in 2020. Conclusions All-cause wrist fractures presenting to U.S. EDs significantly increased from 2013 to 2022 though sports-related wrist fractures did not. Pediatric males and elderly females are most at risk for wrist fractures overall while sports-related wrist fractures predominate in the pediatric population. Youth sports and recreation officials should be aware of the risks to mitigate the incidence of sports-related wrist fractures.

Photoinduced Charge Injection from Shallow Point Defects in Diamond into Water.

Thanks to its low or negative surface electron affinity and chemical inertness, diamond is attracting broad attention as a source material of solvated electrons produced by optical excitation of the solid-liquid interface. Unfortunately, its wide bandgap typically imposes the use of wavelengths in the ultraviolet range, hence complicating practical applications. Here, we probe the photocurrent response of water surrounded by single-crystal diamond surfaces engineered to host shallow nitrogen-vacancy (NV) centers. We observe clear signatures of diamond-induced photocurrent generation throughout the visible range and for wavelengths reaching up to 594 nm. Experiments as a function of laser power suggest that NV centers and other coexisting defects─likely in the form of surface traps─contribute to carrier injection, though we find that NVs dominate the system response in the limit of high illumination intensities. Given our growing understanding of near-surface NV centers and adjacent point defects, these results open new perspectives in the application of diamond-liquid interfaces to photocarrier-initiated chemical and spin processes in fluids.

Probing Correlation of Optical Emission and Defect Sites in Hexagonal Boron Nitride by High-Resolution STEM-EELS.

Optically bright emitters in hexagonal boron nitride (hBN) often acting as a source of a single-photon are mostly attributed to point-defect centers, featuring localized intra-bandgap electronic states. Although vacancies, anti-sites, and impurities have been proposed as candidates, the exact physical and chemical nature of most hBN single-photon emitters (SPEs) within the visible region are still up for debate. Combining site-specific high-angle annular dark-field imaging (HAADF) with electron energy loss spectroscopy (EELS), we resolve and identify a few carbon substitutions among neighboring hBN hexagons, all within the same sample region, from which typical defect emission is observed. Our experimental results are further supported by first-principles calculations, through which the stability and possible optical transitions of the proposed carbon-defect complex are assessed. The presented correlation between optical emission and defects provides valuable information toward the controlled creation of emitters in hBN, highlighting carbon complexes as another probable cause of its visible SPEs.

Patients' under 25 subjective readiness to return to sport after ACL reconstruction with bone-patellar-bone grafts: Autograft vs. allograft.

Purpose: To assess the difference in perceived readiness to return to sport (RTS) within the first year postoperative period between individuals undergoing anterior cruciate ligament (ACL) reconstruction with bone-patellar tendon-bone (BTB) autografts or allografts. Methods: This was a prospective cohort study of patients undergoing primary ACL reconstruction done either with BTB autograft or allograft from 2010 to 2018. Skeletally mature patients aged 14 to 25 were eligible for inclusion. Patients completed the Marx Activity Rating Scale (MARS) questionnaire postoperatively evaluating perceived ability to perform various activities to compare subjective ability to RTS. Those patients who were outside outlined cohort age, failed to complete a single post-operative survey, underwent revision procedures, or underwent simultaneous or staged additional ligament surgery were excluded. Results: Fifty-nine patients (20.1 ± 3.19 years, 57.6 % Male) were included in the study. Sixteen patients underwent ACL reconstruction with allograft (19.8 ± 3.43 years) while 43 patients received autograft (20.2 ± 3.13). At 3 months autograft recipients reported higher perceived ability to cut (P = .003). At 6-months, allograft recipients reported higher perceived ability to run (P = .033), cut (P = .048), and decelerate (P = .008) as well as a higher overall perceived ability to RTS (P = .032). At all other times, there was no significant difference between cohorts' subjective readiness to perform activities. Conclusion: The results of this study indicate that at times within the first year of recovery following ACL reconstruction, patients who receive allografts and autografts may have significantly different perceived ability to perform activities or RTS. However, while present at various times throughout the first year of recovery, any difference in perceived ability to perform activities or in overall RTS is no longer present at 12 months. Level of evidence: Level II, Prospective cohort study.

Comparative digital study using four methods of measurements of the tibial distal anatomical axes for determining the anatomical-mechanical angle in dogs with cranial cruciate ligament rupture.

OBJECTIVE: This study evaluates the amplitude of the anatomical-mechanical angle (AMA-angle) using 4 measuring methods of the tibial distal anatomical axes (DAA) previously described, comparing the literature results to determine if there are significant differences in patients with cranial cruciate ligament (CrCL) rupture. ANIMALS: This study was comprised of 30 tibiae (29 dogs), including 1 bilateral case. METHODS: A retrospective study was selected for this research. DAA measurements were performed on all surgically confirmed cases of canine CrCL rupture at Hospital Veterinário de Especialidades Bruselas from 2019 to 2022. Four different published methods (identified by surname of the corresponding author of the original publication) were compared. Tibial measurements were made using Veterinary Preoperative Orthopedic Planning Pro software (https://vpop-pro.com/) on mediolateral radiographic projections obtained from a digital database. RESULTS: The mean (range) in the DAA method conducted by Hulse obtained a AMA-angle of 5.4° (3.3 to 8.1°), 3.0° (0 to 5.8°) for Osmond et al, 3.2° (0.9 to 6°) for Miles, and 5.9° (2.4 to 8.8°) for Tudury. Differences among the means of the AMA-angle of the authors methods were found with a statistical difference (P < .05), except between Osmond and Miles. The mean AMA-angle with the Osmond method concurred with previous study results that determined the magnitude using the same measurement method of DAA in patients with CrCL rupture. CLINICAL RELEVANCE: The AMA-angle magnitude has been associated with higher sensitivity and specificity for predicting the development of CrCL rupture compared to other anatomical factors evaluated; therefore, future comparisons with different methods of measurement of the DAA between healthy and affected patients are recommended to determine whether any of them can increase the percentage value as a predictive factor for the occurrence of this condition.

Cardiometabolic comorbidities and complications of obesity and chronic kidney disease (CKD).

Obesity and chronic kidney disease are two ongoing progressive clinical pandemics of major public health and clinical care significance. Because of their growing prevalence, chronic indolent course and consequent complications both these conditions place significant burden on the health care delivery system especially in developed countries like the United States. Beyond the chance coexistence of both of these conditions in the same patient based on high prevalence it is now apparent that obesity is associated with and likely has a direct causal role in the onset, progression and severity of chronic kidney disease. The causes and underlying pathophysiology of this are myriad, complicated and multi-faceted. In this review, continuing the theme of this special edition of the journal on " The Cross roads between Endocrinology and Nephrology" we review the epidemiology of obesity related chronic kidney disease (ORCKD), and its various underlying causes and pathophysiology. In addition, we delve into the consequent comorbidities and complications associated with ORCKD with particular emphasis on the cardio metabolic consequences and then review the current body of evidence for available strategies for chronic kidney disease modulation in ORCKD as well as the potential unique role of weight reduction and management strategies in its improvement and risk reduction.

Antigenic Characterization of Novel Human Norovirus GII.4 Variants San Francisco 2017 and Hong Kong 2019.

Norovirus is a major cause of acute gastroenteritis; GII.4 is the predominant strain in humans. Recently, 2 new GII.4 variants, Hong Kong 2019 and San Francisco 2017, were reported. Characterization using GII.4 monoclonal antibodies and serum demonstrated different antigenic profiles for the new variants compared with historical variants.

Through the Eye of a Needle: Understanding the Identities of LGBTQ+ Teachers Within Catholic Institutions in the Philippines.

The pervasive Catholic culture permeates through the social fabric of the Philippines and exerts unique pressures on Filipinos. This study highlighted the unique experiences of Filipino LGBTQ+ educators of private Catholic schools. Using the grounded theory approach, seven participants who identified as LGBTQ+ and taught in private Catholic schools in the Philippines for a minimum of one year were interviewed. Semi-structured interviews with the participants illustrated that these LGBTQ+ educators had to contend with negotiating their identities while carefully navigating through their work environment. This yielded three key themes: (1) Recognizing the political dimension of private schools, (2) Threading the Needle, and (3) Obtaining and Optimizing Safe Spaces. As a result, the Constricting Contexts Model was proposed to better understand and contextualize such factors and emphasize the role that environments and expectations play into the identities of marginalized groups such as the LGBTQ+ community.

The cost-utility of intraoperative tranexamic acid in adult spinal deformity patients undergoing long posterior spinal fusion.

PURPOSE: This study aims to evaluate the cost-utility of intraoperative tranexamic acid (TXA) in adult spinal deformity (ASD) patients undergoing long posterior (≥ 5 vertebral levels) spinal fusion. METHODS: A decision-analysis model was built for a hypothetical 60-year-old adult patient with spinal deformity undergoing long posterior spinal fusion. A comprehensive review of the literature was performed to obtain event probabilities, costs and health utilities at each node. Health utilities were utilized to calculate Quality-Adjusted Life Years (QALYs). A base-case analysis was carried out to obtain the incremental cost and effectiveness of intraoperative TXA. Probabilistic sensitivity analysis was performed to evaluate uncertainty in our model and obtain mean incremental costs, effectiveness, and net monetary benefits. One-way sensitivity analyses were also performed to identify the variables with the most impact on our model. RESULTS: Use of intraoperative TXA was the favored strategy in 88% of the iterations. The mean incremental utility ratio for using intraoperative TXA demonstrated higher benefit and lower cost while being lower than the willingness-to-pay threshold set at $50,000 per quality adjusted life years. Use of intraoperative TXA was associated with a mean incremental net monetary benefit (INMB) of $3743 (95% CI 3492-3995). One-way sensitivity analysis reported cost of blood transfusions due to post-operative anemia to be a major driver of cost-utility analysis. CONCLUSION: Use of intraoperative TXAs is a cost-effective strategy to reduce overall perioperative costs related to post-operative blood transfusions. Administration of intraoperative TXA should be considered for long fusions in ASD population when not explicitly contra-indicated due to patient factors.

Nonclassic Congenital Adrenal Hyperplasia Metabolic Resolution Post Roux-en-Y Gastric Bypass and Associated Weight Loss.

Nonclassic congenital adrenal hyperplasia (NCCAH) is characterized by mild cortisol deficiency, excess androgens and adrenocorticotropin (ACTH) production, and often with various features of dysmetabolic syndrome. Elective bariatric surgery is one of the most effective long-term management strategies for severe obesity. Our case presents a 34-year-old woman with symptomatic NCCAH and class III obesity who status post Roux-en-Y gastric bypass (RYGB) had significant weight loss with metabolic resolution of NCCAH, and no longer required glucocorticoid (GC) therapy. At 11 months post operation and off GC therapy, she had a weight deficit of approximately 160 pounds (72.57 kg) with continued metabolic resolution of NCCAH markers including ACTH, 17-hydroxyprogesterone, and androstenedione. Presently, GC therapy remains one of the few available treatments for symptomatic NCCAH; however, long-term GC therapy has the potential for various complications and side effects. Our case presents elective bariatric surgery as a potential and unique treatment option for patients with NCCAH with associated class III obesity. The exact pathophysiologic basis for this effect and its potential role in long-term management of appropriate NCCAH patients requires further study.

Analysis of Archival Sera from Norovirus-Infected Individuals Demonstrates that Cross-Blocking of Emerging Viruses is Genotype-Specific.

BACKGROUND: Rapidly evolving RNA viruses, such as human norovirus, generate extraordinary sequence diversity, posing a significant challenge to vaccine design. This diversity coupled with short-lasting natural immunity leads to re-infection throughout one's lifetime. How re-exposure shapes humoral immunity to future norovirus strains remains incompletely understood. METHODS: We profiled the antibody responses following two community gastroenteritis outbreaks with GII.2 and GII.6 noroviruses in 1971. Using diverse VLPs, ELISA, and carbohydrate-blocking assays (surrogate for neutralization), we examined the antibody response at acute and convalescent timepoints following GII.6 infection. RESULTS: Convalescent sera displayed strong homologous blocking, demonstrating a 5-fold increase in GII.6 carbohydrate-blockade over acute samples, and broad blocking of diverse archival and modern GII.6 noroviruses. Convalescent sera displayed limited carbohydrate-blocking of heterotypic VLPs, despite high ELISA binding titers. Select individuals developed broad cross-genotype blockade, but this response was established before the second outbreak. Finally, we applied a novel competitive carbohydrate-blocking assay to demonstrate the epitope-specificity and discrete compartments of the neutralizing response. CONCLUSIONS: Our data show that infection generates narrow, focused immunity directed towards the infecting genotype. We did detect broad cross-blocking in specific individuals, but these responses could be attributed to diverse, genotype-specific antibodies pre-dating GII.6 infection.

Longitudinal machine learning uncouples healthy aging factors from chronic disease risks.

To understand human longevity, inherent aging processes must be distinguished from known etiologies leading to age-related chronic diseases. Such deconvolution is difficult to achieve because it requires tracking patients throughout their entire lives. Here, we used machine learning to infer health trajectories over the entire adulthood age range using extrapolation from electronic medical records with partial longitudinal coverage. Using this approach, our model tracked the state of patients who were healthy and free from known chronic disease risk and distinguished individuals with higher or lower longevity potential using a multivariate score. We showed that the model and the markers it uses performed consistently on data from Israeli, British and US populations. For example, mildly low neutrophil counts and alkaline phosphatase levels serve as early indicators of healthy aging that are independent of risk for major chronic diseases. We characterize the heritability and genetic associations of our longevity score and demonstrate at least 1 year of extended lifespan for parents of high-scoring patients compared to matched controls. Longitudinal modeling of healthy individuals is thereby established as a tool for understanding healthy aging and longevity.

Gender diversity at spine surgery academic conferences: a 15-year investigation.

BACKGROUND CONTEXT: Enhancing gender diversity at academic conferences is critical for advancing women's representation and career trajectories in spine surgery. PURPOSE: To discover trends in women's representation at major spine conferences over a 15-year period. STUDY DESIGN/SETTING: Conference records from the 2007-2021 annual meetings of the Congress of Neurological Surgeons, North American Spine Society, and Scoliosis Research Society (SRS). PATIENT SAMPLE: Authors of spine-related presentations. OUTCOME MEASURES: Authorship by gender. METHODS: Retrospective bibliometric analysis with univariate and multivariate modeling to identify trends and predictors of gender diversity. RESULTS: Among 8,948 presentations, 750 (8.4%) had female first authors and 618 (6.9%) had female senior authors. There was no change in rates of female first authorship (p=.41) or senior authorship (p=.88) over time. The strongest predictors of female first authorship were having a female senior author (OR 7.32, p<.001), and delivering presentations at SRS (OR 1.95, p=.001). Factors negatively associated with female first authorship included poster format (OR 0.82, p=.039) and conference location in the United States/Canada (OR 0.76, p=.045). Similar trends were encountered for senior authorship. Productivity per senior author was similar between genders (p=.160); whereas a gender gap in productivity per first author during 2007 to 2011 (p=.020) equalized by 2017 to 2021 (p=.300). Among the 10 most productive authors of each gender, male authors delivered more presentations, but all authors shared similar format, content, and location. CONCLUSIONS: Women's representation in spine-related presentations did not increase at three major conferences over a 15-year period. Our findings regarding the positive effects of female mentorship, and international or virtual venues merit further investigation to address the gender gap. The upstream pipeline of recruiting women into academic spine surgery also needs to be addressed.

Structural and functional insights into the enzymatic plasticity of the SARS-CoV-2 NiRAN Domain.

The enzymatic activity of the SARS-CoV-2 nidovirus RdRp-associated nucleotidyltransferase (NiRAN) domain is essential for viral propagation, with three distinct activities associated with modification of the nsp9 N-terminus, NMPylation, RNAylation, and deRNAylation/capping via a GDP-polyribonucleotidyltransferase reaction. The latter two activities comprise an unconventional mechanism for initiating viral RNA 5'-cap formation, while the role of NMPylation is unclear. The structural mechanisms for these diverse enzymatic activities have not been properly delineated. Here we determine high-resolution cryo-electron microscopy structures of catalytic intermediates for the NMPylation and deRNAylation/capping reactions, revealing diverse nucleotide binding poses and divalent metal ion coordination sites to promote its repertoire of activities. The deRNAylation/capping structure explains why GDP is a preferred substrate for the capping reaction over GTP. Altogether, these findings enhance our understanding of the promiscuous coronaviral NiRAN domain, a therapeutic target, and provide an accurate structural platform for drug development.

Norovirus evolves as one or more distinct clonal populations in immunocompromised hosts.

Noroviruses are a major cause of acute gastroenteritis worldwide and can establish chronic infection in immunocompromised individuals. To investigate the mechanisms of norovirus evolution during chronic infection, we selected seven representative patients from a National Institutes of Health study cohort who sustained norovirus infection for periods ranging from 73 to 1,492 days. Six patients shed viruses belonging to a single genotype (GII.2[PNA], GII.4 New Orleans[P4], GII.4 Den Haag[P4], GII.3[P21], GII.6[P7], or GII.14[P7]) over the period examined, while one patient sequentially shed two genotypes (GII.6[P7] followed by GII.4 Sydney[P31]). Norovirus genomes from consecutive stool samples were sequenced at high resolution (>3,300 reads/nucleotide position) using the Illumina platform and subjected to bioinformatics analysis. Norovirus sequences could be resolved into one or more discrete clonal RNA genomes that persisted within these patients over time. Phylogenetic analyses inferred that clonal populations originated from a single founder virus and not by reinfection with community strains. Estimated evolutionary rates of clonal populations during persistent infection were similar to those of noroviruses from acute infection in the global database, suggesting that inherently higher RNA-dependent polymerase error rates were not associated with the ability to persist. The high-resolution analysis of norovirus diversity and evolution at the population level described here should allow a better understanding of adaptive mutations sustained during chronic infection. IMPORTANCE Noroviruses are an important cause of chronic diarrhea in patients with compromised immune systems. Presently, there are no effective therapies to clear the virus, which can persist for years in the intestinal tract. The goal of our study was to develop a better understanding of the norovirus strains that are associated with these long-term infections. With the remarkable diversity of norovirus strains detected in the immunocompromised patient cohort we studied, it appears that most, if not all, noroviruses circulating in nature may have the capacity to establish a chronic infection when a person is unable to mount an effective immune response. Our work is the most comprehensive genetic data set generated to date in which near full-length genomes from noroviruses associated with chronic infection were analyzed by high-resolution next-generation sequencing. Analysis of this data set led to our discovery that certain patients in our cohort were shedding noroviruses that could be subdivided into distinct haplotypes or populations of viruses that were co-evolving independently. The ability to track haplotypes of noroviruses during chronic infection will allow us to fine-tune our understanding of how the virus adapts and maintains itself in the human host, and how selective pressures such as antiviral drugs can affect these distinct populations.

Structural and functional insights into the enzymatic plasticity of the SARS-CoV-2 NiRAN domain.

The enzymatic activity of the SARS-CoV-2 nidovirus RdRp-associated nucleotidyltransferase (NiRAN) domain is essential for viral propagation, with three distinct activities associated with modification of the nsp9 N terminus, NMPylation, RNAylation, and deRNAylation/capping via a GDP-polyribonucleotidyltransferase reaction. The latter two activities comprise an unconventional mechanism for initiating viral RNA 5' cap formation, while the role of NMPylation is unclear. The structural mechanisms for these diverse enzymatic activities have not been properly delineated. Here, we determine high-resolution cryoelectron microscopy (cryo-EM) structures of catalytic intermediates for the NMPylation and deRNAylation/capping reactions, revealing diverse nucleotide binding poses and divalent metal ion coordination sites to promote its repertoire of activities. The deRNAylation/capping structure explains why GDP is a preferred substrate for the capping reaction over GTP. Altogether, these findings enhance our understanding of the promiscuous coronaviral NiRAN domain, a therapeutic target, and provide an accurate structural platform for drug development.