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Over 300 million individuals worldwide are chronically infected with hepatitis B virus and at risk for progressive liver disease. Due to the lack of a therapy that reliably achieves viral elimination and the variability of liver disease progression, treatment decisions are guided by the degree of liver disease and viral biomarkers as the viral life-cycle is well characterized and largely conserved between individuals. In contrast, the immunological landscape is much more heterogeneous and diverse and the measurement of its components is less well standardized. Due to the lack of a universal and easily measurable set of biomarkers, clinical practice guidelines remain controversial, aiming for a balance between simplifying treatment decisions by reducing biomarker requirements and using all available biomarkers to avoid overtreatment of patients with low risk for disease progression. While approved therapies such as nucleos(t)ide analogs improve patient outcomes, the inability to achieve a complete cure highlights the need for novel therapies. Since no treatment candidate has demonstrated universal efficacy, biomarkers will remain important for treatment stratification. Here, we summarize the current knowledge on virological and immunological biomarkers with a specific focus on how they might be beneficial in guiding treatment decisions in chronic hepatitis B., Competing Interests: None declared., (Thieme. All rights reserved.)

Background and Aims: HBV and HIV coinfection is a common occurrence globally, with significant morbidity and mortality. Both viruses lead to immune dysregulation including changes in natural killer (NK) cells, a key component of antiviral defense and a promising target for HBV cure strategies. Here we used high-throughput single-cell analysis to explore the immune cell landscape in people with HBV mono-infection and HIV/HBV coinfection, on antiviral therapy, with emphasis on identifying the distinctive characteristics of NK cell subsets that can be therapeutically harnessed., Approach and Results: Our data show striking differences in the transcriptional programs of NK cells. HIV/HBV coinfection was characterized by an over-representation of adaptive, KLRC2 -expressing NK cells, including a higher abundance of a chemokine-enriched ( CCL3/CCL4 ) adaptive cluster. The NK cell remodeling in HIV/HBV coinfection was reflected in enriched activation pathways, including CD3ζ phosphorylation and ZAP-70 translocation that can mediate stronger antibody-dependent cellular cytotoxicity responses and a bias toward chemokine/cytokine signaling. By contrast, HBV mono-infection imposed a stronger cytotoxic profile on NK cells and a more prominent signature of "exhaustion" with higher circulating levels of HBsAg. Phenotypic alterations in the NK cell pool in coinfection were consistent with increased "adaptiveness" and better capacity for antibody-dependent cellular cytotoxicity compared to HBV mono-infection. Overall, an adaptive NK cell signature correlated inversely with circulating levels of HBsAg and HBV-RNA in our cohort., Conclusions: This study provides new insights into the differential signature and functional profile of NK cells in HBV and HIV/HBV coinfection, highlighting pathways that can be manipulated to tailor NK cell-focused approaches to advance HBV cure strategies in different patient groups., (Copyright © 2024 American Association for the Study of Liver Diseases.)

Background and Aims: The intrahepatic processes associated with chronic hepatitis B (CHB), especially in the context of hepatitis delta virus (HDV) and HIV co-infection, require a better understanding. Spatial transcriptomics can provide new insights into the complex intrahepatic biological processes, guiding new personalised treatments. Our aim is to evaluate this method characterising the intrahepatic transcriptional landscape, cellular composition and biological pathways in liver biopsy samples from patients with hepatitis B virus (HBV) and HDV or HIV co-infection., Method: The NanoString GeoMx digital spatial profiling platform was employed to assess expression of HBV surface antigen and CD45 in formalin-fixed paraffin-embedded (FFPE) biopsies from three treatment-naïve patients with chronic HBV and HDV or HIV co-infection. The GeoMx Human Whole Transcriptome Atlas assay quantified the expression of genes enriched in specific regions of interest (ROIs). Cell type proportions within ROIs were deconvoluted using a training matrix from the human liver cell atlas. A weighted gene correlation network analysis evaluated transcriptomic signatures across sampled regions., Results: Spatially discrete transcriptomic signatures and distinct biological pathways were associated with HBV infection/disease status and immune responses. Shared features including 'cytotoxicity' and 'B cell receptor signalling' were consistent across patients, suggesting common elements alongside individual traits. HDV/HBV co-infection exhibited upregulated genes linked to apoptosis and immune cell recruitment, whereas HIV/HBV co-infection featured genes related to interferon response regulation. Varied cellular characteristics and immune cell populations, with an abundance of γδT cells in the HDV/HBV sample, were observed within analysed regions. Transcriptional differences in hepatocyte function suggest disrupted metabolic processes in HDV/HBV co-infection potentially impacting disease progression., Conclusion: This proof-of-principle study shows the value of this platform in investigating the complex immune landscape, highlighting relevant host pathways to disease pathogenesis., Competing Interests: Competing interests None declared.

Dynamic regulation of cellular metabolism is important for maintaining homeostasis and can directly influence immune cell function and differentiation, including NK cell responses. Persistent HIV-1 infection leads to a state of chronic immune activation, NK cell subset redistribution, and progressive NK cell dysregulation. In this study, we examined the metabolic processes that characterize NK cell subsets in HIV-1 infection, including adaptive NK cell subpopulations expressing the activating receptor NKG2C, which expand during chronic infection. These adaptive NK cells exhibit an enhanced metabolic profile in HIV-1- individuals infected with human cytomegalovirus (HCMV). However, the bioenergetic advantage of adaptive CD57+NKG2C+ NK cells is diminished during chronic HIV-1 infection, where NK cells uniformly display reduced oxidative phosphorylation (OXPHOS). Defective OXPHOS was accompanied by increased mitochondrial depolarization, structural alterations, and increased DRP-1 levels promoting fission, suggesting that mitochondrial defects are restricting the metabolic plasticity of NK cell subsets in HIV-1 infection. The metabolic requirement for the NK cell response to receptor stimulation was alleviated upon IL-15 pretreatment, which enhanced mammalian target of rapamycin complex 1 (mTORC1) activity. IL-15 priming enhanced NK cell functionality to anti-CD16 stimulation in HIV-1 infection, representing an effective strategy for pharmacologically boosting NK cell responses.

Bacterial spot caused by Xanthomonas euvesicatoria is a major disease of pepper ( Capsicum annuum L.) in warm and humid production environments. Use of genetically resistant cultivars is an effective approach to manage bacterial spot. Two recessive resistance genes, bs5 and bs6 , confer non-race-specific resistance against bacterial spot. The objective of our study was to map these two loci in the pepper genome. We used a genotyping-by-sequencing approach to initially map the position of the two resistances. Segregating populations for bs5 and bs6 were developed by crossing susceptible Early CalWonder (ECW) with near-isogenic lines ECW50R ( bs5 introgression) or ECW60R ( bs6 introgression). Following fine-mapping, bs5 was delimited to a ~535 Kbp interval on chromosome 3, and bs6 to a ~666 Kbp interval in chromosome 6. We identified 14 and 8 candidate resistance genes for bs5 and bs6 , respectively, based on predicted protein coding polymorphisms between ECW and the corresponding resistant parent. This research enhances marker-assisted selection of bs5 and bs6 in breeding programs and is a crucial step towards elucidating the molecular mechanisms underlying the resistances., Competing Interests: AO and BS are applicants for patent WO2021011348A1/US20210071193A1. MM is a cofounder of Row 7 Seeds, but neither receives compensation nor holds equity. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Sharma, Li, Wente, Minsavage, Gill, Ortega, Vallejos, Hart, Staskawicz, Mazourek, Stall, Jones and Hutton.)

Hepatitis delta virus (HDV) is known to cause the most aggressive and severe form of viral hepatitis, yet it remained under-diagnosed but does require early diagnosis for accurate disease staging. Antibody to HDV (anti-HDV) is the primary screening tool and should be assessed in patients with hepatitis B surface antigen (HBsAg) positivity, as HDV is a satellite RNA virus of hepatitis B. Additionally, the viral load (HDV RNA) should be assessed in those with positive anti-HDV, to differentiate between active infection and resolved hepatitis delta. Data regarding immune responses in HDV are limited but show dysfunctional adaptive and innate immunity. Many studies however fail to distinguish between active and resolved infection. Limited treatments are available for HDV, but promise has been shown with the newly approved Bulevirtide, a first-in-class HBV entry inhibitor. Thus immune response during therapy requires further investigation, along with additional targets for HDV cure., (© 2022 The Author. Journal of Viral Hepatitis published by John Wiley & Sons Ltd.)

Single-cell ribonucleic acid (RNA)-sequencing (scRNA-seq) is a powerful tool to study cellular heterogeneity. The high dimensional data generated from this technology are complex and require specialized expertise for analysis and interpretation. The core of scRNA-seq data analysis contains several key analytical steps, which include pre-processing, quality control, normalization, dimensionality reduction, integration and clustering. Each step often has many algorithms developed with varied underlying assumptions and implications. With such a diverse choice of tools available, benchmarking analyses have compared their performances and demonstrated that tools operate differentially according to the data types and complexity. Here, we present Integrated Benchmarking scRNA-seq Analytical Pipeline (IBRAP), which contains a suite of analytical components that can be interchanged throughout the pipeline alongside multiple benchmarking metrics that enable users to compare results and determine the optimal pipeline combinations for their data. We apply IBRAP to single- and multi-sample integration analysis using primary pancreatic tissue, cancer cell line and simulated data accompanied with ground truth cell labels, demonstrating the interchangeable and benchmarking functionality of IBRAP. Our results confirm that the optimal pipelines are dependent on individual samples and studies, further supporting the rationale and necessity of our tool. We then compare reference-based cell annotation with unsupervised analysis, both included in IBRAP, and demonstrate the superiority of the reference-based method in identifying robust major and minor cell types. Thus, IBRAP presents a valuable tool to integrate multiple samples and studies to create reference maps of normal and diseased tissues, facilitating novel biological discovery using the vast volume of scRNA-seq data available., (© The Author(s) 2023. Published by Oxford University Press.)

Background & Aims: Antivirals represent the mainstay of chronic hepatitis B treatment given their efficacy and tolerability, but rates of functional cure remain low during long-term therapy. Treatment discontinuation has emerged as a strategy to maintain partial cure and achieve functional cure in select patient groups. We aimed to evaluate how data from treatment discontinuation studies exploring novel viral and/or immune markers could be applied to the functional cure program., Methods: Treatment discontinuation studies evaluating novel viral and/or immune markers were identified by a systematic search of the PubMed database through to October 30, 2022. Data extraction focused on information regarding novel markers, including identified cut-off levels, timing of measurement, and associated effect on study outcomes of virological relapse, clinical relapse, and HBsAg seroclearance., Results: From a search of 4,492 citations, 33 studies comprising a minimum of 2,986 unique patients met the inclusion criteria. Novel viral markers, HBcrAg and HBV RNA, were demonstrated across most studies to be helpful in predicting off-therapy partial cure, with emerging evidence to support a link with functional cure. From novel immune marker studies, we observed that treatment discontinuation has the potential to trigger immune restoration, which may be associated with a transient virological relapse. To this end, these studies support the combination of virus-directing agents with immunomodulator therapies to induce two key steps underlying functional cure: viral antigen load reduction and restoration of the host immune response., Conclusions: Patients with a favourable profile of novel viral and immune markers stand to benefit from a trial of antiviral treatment discontinuation alongside novel virus-directing agents with the aim of achieving functional cure without excessive risk of severe clinical relapse., Impact and Implications: Select patients with chronic hepatitis B undergoing nucleoside analogue therapy may benefit from a trial of treatment discontinuation, aiming to maintain partial cure and/or achieve functional cure. We propose a profile of novel viral and immune markers to identify patients who are likely to achieve these goals without excessive risk of hepatic decompensation. Furthermore, treatment discontinuation may also be considered as a therapeutic strategy to trigger immune restoration, which may increase the chance of functional cure when used in conjunction with novel virus-directing agents., Competing Interests: L-YM has served as an advisory board member for Gilead Sciences. PK has served as a speaker, a consultant/advisory board member for Abbott Diagnostics, Aligos, Antios Therapeutics, Assembly Biosciences, Gilead Sciences, Janssen, GlaxoSmithKline, Immunocore and Drug Farm, and has received research funding from Gilead Sciences. GZ, AK and UG have no conflicts of interest to disclose. Please refer to the accompanying ICMJE disclosure forms for further details., (© 2023 The Authors.)

The liver is bathed in bacterial products, including lipopolysaccharide transported from the intestinal portal vasculature, but maintains a state of tolerance that is exploited by persistent pathogens and tumours 1-4 . The cellular basis mediating this tolerance, yet allowing a switch to immunity or immunopathology, needs to be better understood for successful immunotherapy of liver diseases. Here we show that a variable proportion of CD8 + T cells compartmentalized in the human liver co-stain for CD14 and other prototypic myeloid membrane proteins and are enriched in close proximity to CD14 high myeloid cells in hepatic zone 2. CD14 + CD8 + T cells preferentially accumulate within the donor pool in liver allografts, among hepatic virus-specific and tumour-infiltrating responses, and in cirrhotic ascites. CD14 + CD8 + T cells exhibit increased turnover, activation and constitutive immunomodulatory features with high homeostatic IL-10 and IL-2 production ex vivo, and enhanced antiviral/anti-tumour effector function after TCR engagement. This CD14 + CD8 + T cell profile can be recapitulated by the acquisition of membrane proteins-including the lipopolysaccharide receptor complex-from mononuclear phagocytes, resulting in augmented tumour killing by TCR-redirected T cells in vitro. CD14 + CD8 + T cells express integrins and chemokine receptors that favour interactions with the local stroma, which can promote their induction through CXCL12. Lipopolysaccharide can also increase the frequency of CD14 + CD8 + T cells in vitro and in vivo, and skew their function towards the production of chemotactic and regenerative cytokines. Thus, bacterial products in the gut-liver axis and tissue stromal factors can tune liver immunity by driving myeloid instruction of CD8 + T cells with immunomodulatory ability., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Although cultivars possessing recessive resistance alleles provide effective control of bacterial spot of pepper ( Capsicum annuum ), the deployed resistance gene, bs5 , is ineffective against Xanthomonas gardneri , one of the pathogenic species. Resistance against X. gardneri was identified in C. annuum accession PI 163192, and this study sought to characterize this novel resistance and to map the resistance gene(s) to the pepper genome. We crossed PI 163192 with the susceptible cultivar Early Calwonder (ECW) to develop resistant near-isogenic lines (NILs) of ECW, designated ECW80R. The novel resistance in ECW80R was determined to be quantitative, recessively inherited, and non-hypersensitive-response causing, and inhibits lesion expansion and chlorosis. Presence of the resistance in NILs decreased the in planta bacterial population by ninefold compared with ECW. Bulked segregant analysis of resistant and susceptible individuals from an F 2 population using whole genome single nucleotide polymorphisms identified a major resistance locus within an approximate 6-Mbp interval on the subtelomeric region of chromosome 11. We developed markers spanning this region and used these to genotype backcross F 2 populations, which further delimited the resistance locus within a 2.3-Mbp interval. The novel resistance locus has been designated bs8 . ECW80R and the linked markers developed in this study should prove useful for breeders seeking to advance this resistance into commercially relevant germplasm and for pyramiding bs8 with other resistance alleles such as bs5 and bs6 . The allele bs8 will help prolong the durability of bacterial spot resistance in pepper and improve resistance to multiple species of Xanthomonas .

Switchgrass rust caused by Puccinia novopanici ( P. novopanici ) has the ability to significantly affect the biomass yield of switchgrass, an important biofuel crop in the United States. A comparative genome analysis of P . novopanici with rust pathogen genomes infecting monocot cereal crops wheat, barley, oats, maize and sorghum revealed the presence of larger structural variations contributing to their genome sizes. A comparative alignment of the rust pathogen genomes resulted in the identification of collinear and syntenic relationships between P. novopanici and P. sorghi ; P. graminis tritici 21-0 ( Pgt 21) and P. graminis tritici Ug99 ( Pgt Ug99) and between Pgt 21 and P. triticina ( Pt ). Repeat element analysis indicated a strong presence of retro elements among different Puccinia genomes, contributing to the genome size variation between ~1 and 3%. A comparative look at the enriched protein families of Puccinia spp. revealed a predominant role of restriction of telomere capping proteins (RTC), disulfide isomerases, polysaccharide deacetylases, glycoside hydrolases, superoxide dismutases and multi-copper oxidases (MCOs). All the proteomes of Puccinia spp. share in common a repertoire of 75 secretory and 24 effector proteins, including glycoside hydrolases cellobiohydrolases, peptidyl-propyl isomerases, polysaccharide deacetylases and protein disulfide-isomerases, that remain central to their pathogenicity. Comparison of the predicted effector proteins from Puccinia spp. genomes to the validated proteins from the Pathogen-Host Interactions database (PHI-base) resulted in the identification of validated effector proteins PgtSR1 (PGTG_09586) from P. graminis and Mlp124478 from Melampsora laricis across all the rust pathogen genomes.

Objective: Tissue-resident memory T cells (T RM ) are vital immune sentinels that provide protective immunity. While hepatic CD8 + T RM have been well described, little is known about the location, phenotype and function of CD4 + T RM ., Design: We used multiparametric flow cytometry, histological assessment and novel human tissue coculture systems to interrogate the ex vivo phenotype, function and generation of the intrahepatic CD4 + T-cell compartment. We also used leukocytes isolated from human leukocyte antigen (HLA)-disparate liver allografts to assess long-term retention., Results: Hepatic CD4 + T cells were delineated into three distinct populations based on CD69 expression: CD69 - , CD69 INT and CD69 HI . CD69 HI CD4 + cells were identified as tissue-resident CD4 + T cells on the basis of their exclusion from the circulation, phenotypical profile (CXCR6 + CD49a + S1PR1 - PD-1 + ) and long-term persistence within the pool of donor-derived leukcoocytes in HLA-disparate liver allografts. CD69 HI CD4 + T cells produced robust type 1 polyfunctional cytokine responses on stimulation. Conversely, CD69 INT CD4 + T cells represented a more heterogenous population containing cells with a more activated phenotype, a distinct chemokine receptor profile (CX 3 CR1 + CXCR3 + CXCR1 + ) and a bias towards interleukin-4 production. While CD69 INT CD4 + T cells could be found in the circulation and lymph nodes, these cells also formed part of the long-term resident pool, persisting in HLA-mismatched allografts. Notably, frequencies of CD69 INT CD4 + T cells correlated with necroinflammatory scores in chronic hepatitis B infection. Finally, we demonstrated that interaction with hepatic epithelia was sufficient to generate CD69 INT CD4 + T cells, while additional signals from the liver microenvironment were required to generate liver-resident CD69 HI CD4 + T cells., Conclusions: High and intermediate CD69 expressions mark human hepatic CD4 + T RM and a novel functionally distinct recirculating population, respectively, both shaped by the liver microenvironment to achieve diverse immunosurveillance., Competing Interests: Competing interests: BW collaborated with and received funding from Bioniz. LJP sat on advisory boards/provided consultancy for Gilead Sciences and SQZ Biotech. KA was funded by a studentship with Dr Falk. MKM received research funding from Gilead Sciences, Hoffmann La Roche and Immunocore. MKM sat on advisory boards/provided consultancy for Gilead, Hoffmann La Roche, Immunocore, VIR, Galapagos NV, GSK, Abbvie and Freeline. ZS collaborated with Bioniz and AstraZeneca and consulted for Boehringer Ingelheim. All other authors declare no conflict of interest., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY. Published by BMJ.)

Chronic hepatitis B (CHB) is associated with significant morbidity and mortality, due to the adverse sequelae of cirrhosis and hepatocellular carcinoma (HCC). To date, antiviral therapy has been reserved for patients with ostensibly active liver disease, fibrosis or cirrhosis, and/or increased risk of HCC. Historically, patients with hepatitis B 'e' antigen (HBeAg)-positive chronic infection, were not offered antiviral therapy. Nevertheless, there has been compelling evidence emerging in recent years, demonstrating that this disease phase is in fact not characterized by immunological tolerance. HBV integration into the human genome is a frequent event found in these patients. Additionally, it may well be associated with active inflammation and fibrosis, even in the presence of persistently normal liver enzymes. Likewise, it appears that the mechanisms of hepatocarcinogenesis are already present during this early stage of the disease. This was reflected in the European Association for the Study of the Liver (EASL) guidelines, where treating patients above the age of 30 years with HBeAg-positive chronic infection was proposed. Lowering the treatment threshold to broaden treatment eligibility is likely to slow disease progression and reduce the risk of developing HCC. The current review discusses the reasons to consider early antiviral therapy in HBeAg-positive chronic infection.

Cure from chronic HBV infection is rare with current therapies. Basic research has helped to fundamentally improve our knowledge of the viral life cycle and virus-host interactions, and provided the basis for several novel drug classes that are currently being developed or are being tested in clinical trials. While these novel compounds targeting the viral life cycle or antiviral immune responses hold great promise, we are still lacking a comprehensive understanding of the immunological and virological processes that occur at the site of infection, the liver. At the International Liver Congress 2021 (ILC 2021), a research think tank on chronic HBV infection focused on mechanisms within the liver that facilitate persistent infection and looked at the research questions that need to be addressed to fill knowledge gaps and identify novel therapeutic strategies. Herein, we summarise the discussion by the think tank and identify the key basic research questions that must be addressed in order to develop more effective strategies for the functional cure of HBV infection., Competing Interests: The authors declare no conflicts of interest that pertain to this work. Please refer to the accompanying ICMJE disclosure forms for further details., (© 2022 The Author(s).)

Background: Hepatitis delta virus (HDV), which causes the most severe form of viral hepatitis, is an obligated hepatitis B (HBV) satellite virus that can either infect naïve subjects simultaneously with HBV (co-infection), or chronically infect HBV carriers (super-infection). An estimated 12 million people are infected by HDV worldwide., Aims: To summarise the most relevant aspects of the molecular biology of HDV, and to discuss the latest understanding of the induced pathology, interactions with the immune system, as well as both approved and investigational treatment options., Methods: References for this review were identified through searches of PubMed with the terms "HDV" "viral hepatitis" "co-infection" and "super-infection," published between 1980 and October 2021 RESULTS: The limited access to the HDV-infected liver has hampered the investigation of the intrahepatic compartment and our understanding of the mechanisms of HDV pathogenesis. In the absence of standardised and sensitive diagnostic tools, HDV is often underdiagnosed and owing to its strong dependence on host cellular factors, the development of direct antiviral agents has been challenging. New therapeutic agents targeting different steps of the viral cycle have recently been investigated, among which bulevirtide (which was conditionally approved by EMA in July 2020) and lonafarnib; both drugs having received orphan drug designation from both the EMA and FDA., Conclusions: The HBV cure programme potentially offers a unique opportunity to enhance HDV treatment strategies. In addition, a more comprehensive analysis of the intrahepatic compartment is mandated to better understand any liver-confined interaction of HDV with the host immune system., (© 2022 The Authors. Alimentary Pharmacology & Therapeutics published by John Wiley & Sons Ltd.)

Viral hepatitis B (HBV) and hepatitis C (HCV) infections remain the most common risk factors for the development of hepatocellular carcinoma (HCC), and their heterogeneous distribution influences the global prevalence of this common type of liver cancer. Typical hepatitis infection elicits various immune responses within the liver microenvironment, and viral persistence induces chronic liver inflammation and carcinogenesis. HBV is directly mutagenic but can also cause low-grade liver inflammation characterized by episodes of intermittent high-grade liver inflammation, liver fibrosis, and cirrhosis, which can progress to decompensated liver disease and HCC. Equally, the absence of key innate and adaptive immune responses in chronic HCV infection dampens viral eradication and induces an exhausted and immunosuppressive liver niche that favors HCC development and progression. The objectives of this review are to (i) discuss the epidemiological pattern of HBV and HCV infections, (ii) understand the host immune response to acute and chronic viral hepatitis, and (iii) explore the link between this diseased immune environment and the development and progression of HCC in preclinical models and HCC patients.

Background: Protection offered by coronavirus disease 2019 (COVID-19) vaccines wanes over time, requiring an evaluation of different boosting strategies to revert such a trend and enhance the quantity and quality of Spike-specific humoral and cellular immune responses. These immunological parameters in homologous or heterologous vaccination boosts have thus far been studied for mRNA and ChAdOx1 nCoV-19 vaccines, but knowledge on individuals who received a single dose of Ad26.COV2.S is lacking., Methods: We studied Spike-specific humoral and cellular immunity in Ad26.COV2.S-vaccinated individuals (n = 55) who were either primed with Ad26.COV2.S only (n = 13) or were boosted with a homologous (Ad26.COV2.S, n = 28) or heterologous (BNT162b2, n = 14) second dose. We compared our findings with the results found in individuals vaccinated with a single (n = 16) or double (n = 44) dose of BNT162b2., Findings: We observed that a strategy of heterologous vaccination enhanced the quantity and breadth of both Spike-specific humoral and cellular immunity in Ad26.COV2.S-vaccinated individuals. In contrast, the impact of the homologous boost was quantitatively minimal in Ad26.COV2.S-vaccinated individuals, and Spike-specific antibodies and T cells were narrowly focused to the S1 region., Conclusions: Despite the small sample size of the study and the lack of well-defined correlates of protection against COVID-19, the immunological features detected support the utilization of a heterologous vaccine boost in individuals who received Ad26.COV2.S vaccination., Funding: This study is partially supported by the Singapore Ministry of Health's National Medical Research Council under its COVID-19 Research Fund (COVID19RF3-0060, COVID19RF-001, and COVID19RF-008), The Medical College St. Bartholomew's Hospital Trustees - Pump Priming Fund for SMD COVID-19 Research., Competing Interests: N.L.B. and A.B. reported a patent for a method to monitor SARS-CoV-2-specific T cells in biological samples pending. The other authors declare no competing interests., (© 2021 The Author(s).)

Background: The presentation of SARS-CoV-2 infection varies from asymptomatic to severe COVID-19. Similarly, high variability in the presence, titre and duration of specific antibodies has been reported. While some host factors determining these differences, such as age and ethnicity have been identified, the underlying molecular mechanisms underpinning these differences remain poorly defined., Methods: We analysed serum and PBMC from 17 subjects with a previous PCR-confirmed SARS-CoV-2 infection and 10 unexposed volunteers following the first wave of the pandemic, in the UK. Anti-NP IgG and neutralising antibodies were measured, as well as a panel of infection and inflammation related cytokines. The virus-specific T cell response was determined by IFN-γ ELISPOT and flow cytometry after overnight incubation of PBMCs with pools of selected SARS-CoV-2 specific peptides., Results: Seven of 17 convalescent subjects had undetectable levels of anti-NP IgG, and a positive correlation was shown between anti-NP IgG levels and the titre of neutralising antibodies (IC50). In contrast, a discrepancy was noted between antibody levels and T cell IFN-γ production by ELISpot following stimulation with specific peptides. Among the analysed cytokines, β-NGF and IL-1α levels were significantly different between anti-NP positive and negative subjects, and only β-NGF significantly correlated with anti-NP positivity. Interestingly, CD4 + T cells of anti-NP negative subjects expressed lower amounts of the β-NGF-specific receptor TrkA., Conclusions: Our results suggest that the β-NGF/TrkA signalling pathway is associated with the production of anti-NP specific antibody in mild SARS-CoV-2 infection and the mechanistic regulation of this pathway in COVID-19 requires further investigation., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be constructed as a potential conflict of interest., (Copyright © 2022 Usai, Gibbons, Pade, Li, Jacobs, McKnight, Kennedy and Gill.)

Virus-induced gene silencing (VIGS) is an efficient method for functional characterization of genes in monocot and dicot plants via transient silencing of gene(s) of interest. Among various virus vectors, Barley stripe mosaic virus (BSMV) is established as a vector of choice to silence genes in wheat and barley. BSMV is a single-stranded positive-sense RNA virus with a tripartite genome consisting of α, β, and γ RNAs. BSMV-based VIGS has been used to silence both abiotic and biotic stress response genes in various growth stages of plants. Here we describe an efficient and effective protocol to successfully silence wheat and barley genes expressing in various tissues using this approach., (© 2022. Springer Science+Business Media, LLC, part of Springer Nature.)

Objective: The involvement of HBV DNA integration in promoting hepatocarcinogenesis and the extent to which the intrahepatic HBV reservoir modulates liver disease progression remains poorly understood. We examined the intrahepatic HBV reservoir, the occurrence of HBV DNA integration and its impact on the hepatocyte transcriptome in hepatitis B 'e' antigen (HBeAg)-negative chronic hepatitis B (CHB)., Design: Liver tissue from 84 HBeAg-negative patients with CHB with low (n=12), moderate (n=25) and high (n=47) serum HBV DNA was analysed. Covalently closed circular DNA (cccDNA), pregenomic RNA (pgRNA) were evaluated by quantitative PCR, whole exome and transcriptome sequencing was performed by Illumina, and the burden of HBV DNA integrations was evaluated by digital droplet PCR., Results: Patients with low and moderate serum HBV DNA displayed comparable intrahepatic cccDNA and pgRNA, significantly lower than in patients with high HBV DNA, while hepatitis B core-related antigen correlated strongly with the intrahepatic HBV reservoir, reflecting cccDNA quantity. Whole exome integration was detected in a significant number of patients (55.6%, 14.3% and 25% in high, moderate and low viraemic patients, respectively), at a frequency ranging from 0.5 to 157 integrations/1000 hepatocytes. Hepatitis B surface antigen >5000 IU/mL predicted integration within the exome and these integrations localised in genes involved in hepatocarcinogenesis, regulation of lipid/drug metabolism and antiviral/inflammatory responses. Transcript levels of specific genes, including the proto-oncogene hRAS, were higher in patients with HBV DNA integration, supporting an underlying oncogenic risk in patients with low-level to moderate-level viraemia., Conclusions: HBV DNA integration occurs across all HBeAg-negative patients with CHB, including those with a limited HBV reservoir; localising in genes involved in carcinogenesis and altering the hepatocyte transcriptome., Competing Interests: Competing interests: PTFK has collaborative grant funding from Gilead, participates in advisory boards/provides consultancy to Gilead, Janssen and is an investigator for industry-led trials with Gilead, Janssen, Alere, Assembly Biosciences, GSK and Roche., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

HBeAg is a marker of HBV-activity, and HBeAg-loss predicts a favorable clinical outcome. Here, we characterize HBeAg-levels across different phases of HBV infection, their correlation with virological/biochemical markers and the virological response to anti-HBV therapy. Quantitative HBeAg (qHBeAg, DiaSorin) is assessed in 101 HBeAg+ patients: 20 with acute-infection, 20 with chronic infection, 32 with chronic hepatitis and 29 with immunosuppression-driven HBV-reactivation (HBV-R). A total of 15/29 patients with HBV-R are monitored for >12 months after starting TDF/ETV. qHBeAg is higher in immunosuppression-driven HBV-R (median[IQR]:930[206-1945]PEIU/mL) and declines in chronic hepatitis (481[28-1393]PEIU/mL, p = 0.03), suggesting HBeAg production, modulated by the extent of immunological pressure. This is reinforced by the negative correlation between qHBeAg and ALT in acute infection (Rho = -0.66, p = 0.006) and chronic hepatitis (Rho = -0.35; p = 0.05). Interestingly, qHBeAg strongly and positively correlates with qHBsAg across the study groups, suggesting cccDNA as a major source of both proteins in the setting of HBeAg positivity (with limited contribution of integrated HBV-DNA to HBsAg production). Focusing on 15 patients with HBV-R starting TDF/ETV, virological suppression and HBeAg-loss are achieved in 60% and 53.3%. Notably, the combination of qHBeAg > 2000 PEIU/mL + qHBsAg > 52,000 IU/mL at HBV-R is the only factor predicting no HBeAg loss (HBeAg loss: 0% with vs. 72.7% without qHBeAg > 2000 PEIU/mL + qHBsAg > 52,000 IU/mL, p = 0.03). In conclusion, qHBeAg varies over the natural course of HBV infection, according to the extent of immunological pressure. In the setting of HBV-R, qHBeAg could be useful in predicting the treatment response under immunosuppression.

Plant diseases are among the major causes of crop yield losses around the world. To confer disease resistance, conventional breeding relies on the deployment of single resistance (R) genes. However, this strategy has been easily overcome by constantly evolving pathogens. Disabling susceptibility (S) genes is a promising alternative to R genes in breeding programs, as it usually offers durable and broad-spectrum disease resistance. In Arabidopsis , the S gene DMR6 ( AtDMR6 ) encodes an enzyme identified as a susceptibility factor to bacterial and oomycete pathogens. Here, we present a model-to-crop translational work in which we characterize two AtDMR6 orthologs in tomato, SlDMR6-1 and SlDMR6-2. We show that SlDMR6-1 , but not SlDMR6-2 , is up-regulated by pathogen infection. In agreement, Sldmr6-1 mutants display enhanced resistance against different classes of pathogens, such as bacteria, oomycete, and fungi. Notably, disease resistance correlates with increased salicylic acid (SA) levels and transcriptional activation of immune responses. Furthermore, we demonstrate that SlDMR6-1 and SlDMR6-2 display SA-5 hydroxylase activity, thus contributing to the elucidation of the enzymatic function of DMR6. We then propose that SlDMR6 duplication in tomato resulted in subsequent subfunctionalization, in which SlDMR6-2 specialized in balancing SA levels in flowers/fruits, while SlDMR6-1 conserved the ability to fine-tune SA levels during pathogen infection of the plant vegetative tissues. Overall, this work not only corroborates a mechanism underlying SA homeostasis in plants, but also presents a promising strategy for engineering broad-spectrum and durable disease resistance in crops., Competing Interests: The authors declare no competing interest.

Stagonospora nodorum blotch (SNB) is an economically important wheat disease caused by the necrotrophic fungus Parastagonospora nodorum. SNB resistance in wheat is controlled by several quantitative trait loci (QTLs). Thus, identifying novel resistance/susceptibility QTLs is crucial for continuous improvement of the SNB resistance. Here, the hard winter wheat association mapping panel (HWWAMP) comprising accessions from breeding programs in the Great Plains region of the US, was evaluated for SNB resistance and necrotrophic effectors (NEs) sensitivity at the seedling stage. A genome-wide association study (GWAS) was performed to identify single-nucleotide polymorphism (SNP) markers associated with SNB resistance and effectors sensitivity. We found seven significant associations for SNB resistance/susceptibility distributed over chromosomes 1B, 2AL, 2DS, 4AL, 5BL, 6BS, and 7AL. Two new QTLs for SNB resistance/susceptibility at the seedling stage were identified on chromosomes 6BS and 7AL, whereas five QTLs previously reported in diverse germplasms were validated. Allele stacking analysis at seven QTLs explained the additive and complex nature of SNB resistance. We identified accessions ('Pioneer-2180' and 'Shocker') with favorable alleles at five of the seven identified loci, exhibiting a high level of resistance against SNB. Further, GWAS for sensitivity to NEs uncovered significant associations for SnToxA and SnTox3, co-locating with previously identified host sensitivity genes (Tsn1 and Snn3). Candidate region analysis for SNB resistance revealed 35 genes of putative interest with plant defense response-related functions. The QTLs identified and validated in this study could be easily employed in breeding programs using the associated markers to enhance the SNB resistance in hard winter wheat.

Introduction: SARS-CoV-2 antibody detection serves as an important diagnostic marker for past SARS-CoV-2 infection and is essential to determine the spread of COVID-19, monitor potential COVID-19 long-term effects, and to evaluate possible protection from reinfection. A study was conducted across three hospital sites in a large central London NHS Trust in the UK, to evaluate the prevalence and duration of SARS-CoV-2 IgG antibody positivity in healthcare workers. Methods: A matrix equivalence study consisting of 228 participants was undertaken to evaluate the Abbott Panbio™ COVID-19 IgG/IgM rapid test device. Subsequently, 2001 evaluable healthcare workers (HCW), representing a diverse population, were enrolled in a HCW study between June and August 2020. A plasma sample from each HCW was evaluated using the Abbott Panbio™ COVID-19 IgG/IgM rapid test device, with confirmation of IgG-positive results by the Abbott Architect TM SARS-CoV-2 IgG assay. 545 participants, of whom 399 were antibody positive at enrolment, were followed up at 3 months. Results: The Panbio™ COVID-19 IgG/IgM rapid test device demonstrated a high concordance with laboratory tests. SARS-CoV-2 antibodies were detected in 506 participants (25.3%) at enrolment, with a higher prevalence in COVID-19 frontline (28.3%) than non-frontline (19.9%) staff. At follow-up, 274/399 antibody positive participants (68.7%) retained antibodies; 4/146 participants negative at enrolment (2.7%) had seroconverted. Non-white ethnicity, older age, hypertension and COVID-19 symptoms were independent predictors of higher antibody levels (OR 1.881, 2.422-3.034, 2.128, and 1.869 respectively), based on Architect™ index quartiles; participants in the first three categories also showed a greater antibody persistence at 3 months. Conclusion: The SARS-CoV-2 anti-nucleocapsid IgG positivity rate among healthcare staff was high, declining by 31.3% during the 3-month follow-up interval. Interestingly, the IgG-positive participants with certain risk factors for severe COVID-19 illness (older age, Black or Asian Ethnicity hypertension) demonstrated greater persistence over time when compared to the IgG-positive participants without these risk factors., Competing Interests: The authors declare that this study received funding from Abbott Rapid Diagnostics. The funder had the following involvement in the study: study concept, data analysis, statistical analysis, admin/technical support, ethics and critical review of manuscript, Electronic Data Capture database development and management, statistical programming., (Copyright © 2021 Choudhry, Drysdale, Usai, Leighton, Sonagara, Buchanan, Nijjar, Thomas, Hopkins, Cutino-Moguel, Gill, Foster and Kennedy.)

Chronic hepatitis B (CHB) remains a global healthcare burden. Although the recent developments in the field have led to a reduction in incidence, the morbidity and mortality including liver cirrhosis and hepatocellular carcinoma (HCC) remain a formidable challenge. Advances in understanding the immunopathogenesis of CHB have led to a recent change in clinical categorization. EASL introduced the term hepatitis B 'e' antigen (HBeAg)-negative chronic infection, to replace the historical term 'inactive carrier' disease phase, the commonest CHB phase. Although this disease phase is associated with a favorable prognosis, it is not a truly 'inactive' disease phase with no ostensible liver disease, as inferred by the previous anachronistic terminology, and the risk of spontaneous reactivation and the potential risk of disease progression and HCC development are not negligible. Likewise, the APASL also uses the term "Incidentally Detected Asymptomatic Hepatitis B surface antigen (HBsAg)-positive Subject (IDAHS)", comprising all HBsAg-positive subjects who are incidentally detected during routine tests, without any previous or present symptoms of liver disease. This entity includes HBV infection with varied stages of liver disease. Antiviral treatment is generally reserved for patients with active inflammation and/or at risk of disease progression and HCC development. HBsAg loss is considered an optimal treatment endpoint, and may also be achievable in HBeAg-negative chronic infection and IDAHS. In light of this, and the emerging novel HBV therapies, lowering the treatment threshold and a 'Treat All' approach should now be considered. In this review, we summarize the literature and guidance on HBeAg-negative chronic infection, and we make a concerted effort to present the reasons why the one-dimensional term 'inactive carrier' should be abandoned.

Background & Aims: Chronic liver disease (CLD) and cirrhosis are associated with immune dysregulation, leading to concerns that affected patients may be at risk of adverse outcomes following SARS-CoV-2 infection. We aimed to determine the impact of COVID-19 on patients with pre-existing liver disease, which currently remains ill-defined., Methods: Between 25th March and 8th July 2020, data on 745 patients with CLD and SARS-CoV-2 (including 386 with and 359 without cirrhosis) were collected by 2 international registries and compared to data on non-CLD patients with SARS-CoV-2 from a UK hospital network., Results: Mortality was 32% in patients with cirrhosis compared to 8% in those without (p <0.001). Mortality in patients with cirrhosis increased according to Child-Pugh class (A [19%], B [35%], C [51%]) and the main cause of death was from respiratory failure (71%). After adjusting for baseline characteristics, factors associated with death in the total CLD cohort were age (odds ratio [OR] 1.02; 1.01-1.04), Child-Pugh A (OR 1.90; 1.03-3.52), B (OR 4.14; 2.4-7.65), or C (OR 9.32; 4.80-18.08) cirrhosis and alcohol-related liver disease (OR 1.79; 1.03-3.13). Compared to patients without CLD (n = 620), propensity-score-matched analysis revealed significant increases in mortality in those with Child-Pugh B (+20.0% [8.8%-31.3%]) and C (+38.1% [27.1%-49.2%]) cirrhosis. Acute hepatic decompensation occurred in 46% of patients with cirrhosis, of whom 21% had no respiratory symptoms. Half of those with hepatic decompensation had acute-on-chronic liver failure., Conclusions: In the largest such cohort to date, we demonstrate that baseline liver disease stage and alcohol-related liver disease are independent risk factors for death from COVID-19. These data have important implications for the risk stratification of patients with CLD across the globe during the COVID-19 pandemic., Lay Summary: This international registry study demonstrates that patients with cirrhosis are at increased risk of death from COVID-19. Mortality from COVID-19 was particularly high among patients with more advanced cirrhosis and those with alcohol-related liver disease., Competing Interests: Conflicts of interest The authors declare no conflicts of interest. Please refer to the accompanying ICMJE disclosure forms for further details., (Copyright © 2020 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.)

Increasing evidences suggest that HBsAg-production varies across HBV-genotypes. HBsAg C-terminus plays a crucial role for HBsAg-secretion. Here, we evaluate HBsAg-levels in different HBV-genotypes in HBeAg-negative chronic infection, the correlation of specific mutations in HBsAg C-terminus with HBsAg-levels in-vivo, their impact on HBsAg-secretion in-vitro and on structural stability in-silico .HBsAg-levels were investigated in 323 drug-naïve HBeAg-negative patients chronically infected with HBV genotype-D( N  = 228), -A( N  = 65) and -E( N  = 30). Genotype-D was characterized by HBsAg-levels lower than genotype-A and -E (3.3[2.7-3.8]IU/ml; 3.8[3.5-4.2]IU/ml and 3.9[3.7-4.2]IU/ml, P  < 0.001). Results confirmed by multivariable analysis correcting for patients'demographics, HBV-DNA, ALT and infection-status.In genotype-D, specific C-terminus mutations (V190A-S204N-Y206C-Y206F-S210N) significantly correlate with HBsAg<1000IU/ml( P -value from <0.001 to 0.04). These mutations lie in divergent pathways involving other HBsAg C-terminus mutations: V190A + F220L (Phi = 0.41, P  = 0.003), S204N + L205P (Phi = 0.36, P  = 0.005), Y206F + S210R (Phi = 0.47, P  < 0.001) and S210N + F220L (Phi = 0.40, P  = 0.006). Notably, patients with these mutational pairs present HBsAg-levels 1log lower than patients without them( P -value from 0.003 to 0.02). In-vitro , the above-mentioned mutational pairs determined a significant decrease in HBsAg secretion-efficiency compared to wt( P -value from <0.001 to 0.02). Structurally, these mutational pairs reduced HBsAg C-terminus stability and determined a rearrangement of this domain.In conclusion, HBsAg-levels in genotype-D are significantly lower than in genotype-A and -E in HBeAg-negative patients. In genotype-D, specific mutational clusters in HBsAg C-terminus correlate with lower HBsAg-levels in-vivo , hamper HBsAg-release in-vitro and affect its structural stability, supporting their detrimental role on HBsAg-secretion. In this light, genotypic-testing can be a valuable tool to optimize the clinical interpretation of HBsAg in genotype-D and to provide information on HBV-pathogenicity and disease-progression.

Competing Interests: Competing interests: GZ and USG have no conflicts of interest to declare; PTFK has collaborative grant funding from Gilead, participates in advisory board/provides consultancy to Gilead, GSK, Janssen and is an investigator for industry led trials with Abbott, Gilead, Janssen, Roche and Springbank.

Objective: The COVID-19 pandemic has placed increased strain on healthcare systems worldwide with enormous reorganisation undertaken to support 'COVID-centric' services. Non-COVID-19 admissions reduced secondary to public health measures to halt viral transmission. We aimed to understand the impact of the response to COVID-19 on the outcomes of upper gastrointestinal (UGI) bleeds., Design/methods: A retrospective observational multicentre study comparing outcomes following endoscopy for UGI bleeds from 24 March 2020 to 20 April 2020 to the corresponding dates in 2019. The primary outcome was in-hospital survival at 30 days with secondary outcomes of major rebleeding within 30 days postprocedure and intervention at the time of endoscopy., Results: 224 endoscopies for 203 patients with UGI bleeds were included within this study. 19 patients were diagnosed with COVID-19. There was a 44.4% reduction in the number of procedures performed between 2019 and 2020. Endoscopies performed for UGI bleeds in the COVID-19 era were associated with an adjusted reduced 30-day survival (OR 0.25, 95% CI 0.08-0.67). There was no increased risk of major rebleeding or interventions during this era. Patients with COVID-19 did not have reduced survival or increased complication rates., Conclusion: Endoscopy for UGI bleeds in the COVID-19 era is associated with reduced survival. No clear cause has been identified but we suspect that this is a secondary effect of the response to the COVID-19 pandemic. Urgent work is required to encourage the public to seek medical help if required and to optimise patient pathways to ensure that the best possible care is provided., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

Background & Aims: Chronic hepatitis B virus (HBV) infection is characterized by the presence of defective viral envelope proteins (hepatitis B surface antigen [HBsAg]) and the duration of infection-most patients acquire the infection at birth or during the first years of life. We investigated the effects of these factors on patients' lymphocyte and HBV-specific T-cell populations., Methods: We collected blood samples and clinical data from 243 patients with HBV infection (3-75 years old) in the United Kingdom and China. We measured levels of HBV DNA, HBsAg, hepatitis B e antigen, and alanine aminotransferase; analyzed HBV genotypes; and isolated peripheral blood mononuclear cells (PBMCs). In PBMCs from 48 patients with varying levels of serum HBsAg, we measured 40 markers on nature killer and T cells by mass cytometry. PBMCs from 189 patients with chronic infection and 38 patients with resolved infections were incubated with HBV peptide libraries, and HBV-specific T cells were identified by interferon gamma enzyme-linked immune absorbent spot (ELISpot) assays or flow cytometry. We used multivariate linear regression and performed variable selection using the Akaike information criterion to identify covariates associated with HBV-specific responses of T cells., Results: Although T- and natural killer cell phenotypes and functions did not change with level of serum HBsAg, numbers of HBs-specific T cells correlated with serum levels of HBsAg (r = 0.3367; P < .00001). After we performed the variable selection, the multivariate linear regression model identified patient age as the only factor significantly associated with numbers of HBs-specific T cells (P = .000115). In patients younger than 30 years, HBs-specific T cells constituted 28.26% of the total HBV-specific T cells; this value decreased to 7.14% in patients older than 30 years., Conclusions: In an analysis of immune cells from patients with chronic HBV infection, we found that the duration of HBsAg exposure, rather than the quantity of HBsAg, was associated with the level of anti-HBV immune response. Although the presence of HBs-specific T cells might not be required for the clearance of HBV infection in all patients, strategies to restore anti-HBV immune responses should be considered in patients younger than 30 years., (Copyright © 2020 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Brachypodium distachyon is an annual C3 grass used as a monocot model system in functional genomics research. Insertional mutagenesis is a powerful tool for both forward and reverse genetics studies. In this study, we explored the possibility of using the tobacco retrotransposon Tnt1 to create a transposon-based insertion mutant population in B. distachyon. We developed transgenic B. distachyon plants expressing Tnt1 (R0) and in the subsequent regenerants (R1) we observed that Tnt1 actively transposed during somatic embryogenesis, generating an average of 6.37 insertions per line in a population of 19 independent R1 regenerant plants analyzed. In seed-derived progeny of R1 plants, Tnt1 segregated in a Mendelian ratio of 3:1 and no new Tnt1 transposition was observed. A total of 126 flanking sequence tags (FSTs) were recovered from the analyzed R0 and R1 lines. Analysis of the FSTs showed a uniform pattern of insertion in all the chromosomes (1-5) without any preference for a particular chromosome region. Considering the average length of a gene transcript to be 3.37 kb, we estimated that 29 613 lines are required to achieve a 90% possibility of tagging a given gene in the B. distachyon genome using the Tnt1-based mutagenesis approach. Our results show the possibility of using Tnt1 to achieve near-saturation mutagenesis in B. distachyon, which will aid in functional genomics studies of other C3 grasses., (© 2020 The Authors. The Plant Journal published by Society for Experimental Biology and John Wiley & Sons Ltd.)

Xanthomonas species, Pseudomonas syringae and Ralstonia species are bacterial plant pathogens that cause significant yield loss in many crop species. Generating disease-resistant crop varieties can provide a more sustainable solution to control yield loss compared to chemical methods. Plant immune receptors encoded by nucleotide-binding, leucine-rich repeat (NLR) genes typically confer resistance to pathogens that produce a cognate elicitor, often an effector protein secreted by the pathogen to promote virulence. The diverse sequence and presence/absence variation of pathogen effector proteins within and between pathogen species usually limits the utility of a single NLR gene to protecting a plant from a single pathogen species or particular strains. The NLR protein Recognition of XopQ 1 (Roq1) was recently identified from the plant Nicotiana benthamiana and mediates perception of the effector proteins XopQ and HopQ1 from Xanthomonas and P. syringae respectively. Unlike most recognized effectors, alleles of XopQ/HopQ1 are highly conserved and present in most plant pathogenic strains of Xanthomonas and P. syringae . A homolog of XopQ/HopQ1, named RipB, is present in most Ralstonia strains. We found that Roq1 confers immunity to Xanthomonas , P. syringae , and Ralstonia when expressed in tomato. Strong resistance to Xanthomonas perforans was observed in three seasons of field trials with both natural and artificial inoculation. The Roq1 gene can therefore be used to provide safe, economical, and effective control of these pathogens in tomato and other crop species and reduce or eliminate the need for traditional chemical controls., (Copyright © 2020 Thomas, Hendrich, Gill, Allen, Hutton and Schultink.)