1 3529 210 ILLUMINATING THE LIVE-CELL DYNAMICS OF HEPATITIS B VIRUS COVALENTLY CLOSED CIRCULAR DNA USING THE CRISPR-TAG SYSTEM. THE COVALENTLY CLOSED CIRCULAR DNA (CCCDNA) OF HEPATITIS B VIRUS (HBV) IS THE MAJOR OBSTACLE TO CURING CHRONIC HEPATITIS B (CHB). CURRENT CCCDNA DETECTION METHODS ARE MOSTLY BASED ON BIOCHEMICAL EXTRACTION AND BULK MEASUREMENTS. THEY NEVERTHELESS GENERATED A GENERAL SKETCH OF ITS BIOLOGICAL FEATURES. HOWEVER, AN UNDERSTANDING OF THE SPATIOTEMPORAL FEATURES OF CCCDNA IS STILL LACKING. TO ACHIEVE THIS, WE ESTABLISHED A SYSTEM COMBINING CRISPR-TAG AND RECOMBINANT HBV MINICIRCLE TECHNOLOGY TO VISUALIZE CCCDNA AT SINGLE-CELL LEVEL IN REAL TIME. USING THIS SYSTEM, WE FOUND THAT THE OBSERVED RECOMBINANT CCCDNA (RCCCDNA) CORRELATED QUANTITATIVELY WITH ITS ACTIVE TRANSCRIPTS WHEN A LOW TO MEDIUM NUMBER OF FOCI (<20) ARE PRESENT, BUT THIS CORRELATION WAS LOST IN CELLS HARBORING HIGH COPY NUMBERS (>/=20) OF RCCCDNA. THE DISRUPTION OF HBX EXPRESSION SEEMS TO DISPLACE CCCDNA FROM THE DCAS9-ACCESSIBLE REGION, WHILE HBX COMPLEMENTATION RESTORED THE NUMBER OF OBSERVABLE CCCDNA FOCI. THIS INDICATED REGULATION OF CCCDNA ACCESSIBILITY BY HBX. SECOND, OBSERVABLE HBV AND DUCK HBV (DHBV) CCCDNA MOLECULES ARE SUBSTANTIALLY LOST DURING CELL DIVISION, AND THE REMAINING ONES WERE DISTRIBUTED RANDOMLY TO DAUGHTER CELLS. IN CONTRAST, KAPOSI'S SARCOMA-ASSOCIATED HERPESVIRUS (KSHV)-DERIVED EPISOMES CAN BE RETAINED IN A LANA (LATENCY-ASSOCIATED NUCLEAR ANTIGEN)-DEPENDENT MANNER. LAST, THE DYNAMICS OF RCCCDNA EPISOMES IN NUCLEI DISPLAYED CONFINED DIFFUSION AT SHORT TIME SCALES, WITH DIRECTIONAL TRANSPORT OVER LONGER TIME SCALES. IN CONCLUSION, THIS SYSTEM ENABLES THE STUDY OF PHYSIOLOGICAL KINETICS OF CCCDNA AT THE SINGLE-CELL LEVEL. THE DIFFERENTIAL ACCESSIBILITY OF RCCCDNA TO DCAS9 UNDER VARIOUS PHYSIOLOGICAL CONDITIONS MAY BE EXPLOITED TO ELUCIDATE THE COMPLEX TRANSCRIPTIONAL AND EPIGENETIC REGULATION OF THE HBV MINICHROMOSOME. IMPORTANCE UNDERSTANDING THE FORMATION AND MAINTENANCE OF HBV CCCDNA HAS ALWAYS BEEN A CENTRAL ISSUE IN THE STUDY OF HBV PATHOBIOLOGY. HOWEVER, LITTLE PROGRESS HAS BEEN MADE DUE TO THE LACK OF ROBUST ASSAY SYSTEMS AND ITS RESISTANCE TO GENETIC MODIFICATION. HERE, A LIVE-CELL IMAGING SYSTEM BY GRAFTING CRISPR-TAG INTO THE RECOMBINANT CCCDNA WAS ESTABLISHED TO VISUALIZE ITS MOLECULAR BEHAVIOR IN REAL TIME. WE FOUND THAT THE ACCESSIBILITY OF RCCCDNA TO DCAS9-BASED IMAGING IS RELATED TO HBX-REGULATED MECHANISMS. WE ALSO CONFIRMED THE SUBSTANTIAL LOSS OF OBSERVABLE RCCCDNA IN ONE-ROUND CELL DIVISION AND RANDOM DISTRIBUTION OF THE REMAINING MOLECULES. MOLECULAR DYNAMICS ANALYSIS REVEALED THE CONFINED MOVEMENT OF THE RCCCDNA EPISOME, SUGGESTING ITS JUXTAPOSITION TO CHROMATIN DOMAINS. OVERALL, THIS NOVEL SYSTEM OFFERS A UNIQUE PLATFORM TO INVESTIGATE THE INTRANUCLEAR DYNAMICS OF CCCDNA WITHIN LIVE CELLS. 2023 2 631 30 BIOLOGICAL AND SYNTHETIC TARGET DMARDS IN PSORIATIC ARTHRITIS. PSORIATIC ARTHRITIS (PSA) IS A CHRONIC MULTI-FACETED IMMUNE-MEDIATED SYSTEMIC DISORDER, CHARACTERIZED BY ARTICULAR, CUTANEOUS, ENTHESIS, NAIL AND SPINE INVOLVEMENT. ARTICULAR MANIFESTATIONS OF PSA ARE PARTICULARLY COMMON AND HIGHLY DISABLING FOR PATIENTS, WHILE THE HETEROGENEOUS CLINICAL SUBSETS OF THE DISEASE ARE CHALLENGING FOR CLINICIANS. IN RECENT YEARS, RESEARCH HAS MADE MANY ADVANCES IN UNDERSTANDING THE PATHOGENESIS OF THE DISEASE FROM GENETIC, EPIGENETIC AND MOLECULAR POINTS OF VIEW. NEW DRUGS ARE NOW AVAILABLE FOR THE TREATMENT OF THIS CONDITION, AND, IN PARTICULAR, TNF-ALFA INHIBITORS, HISTORICALLY THE FIRST BIOLOGICALS APPROVED IN PSA, ARE NOW JUXTAPOSED BY NEW BIOLOGICAL DISEASE MODIFYING ANTI-RHEUMATIC DRUGS (BDMARDS) WITH DIFFERENT MODES OF ACTION. TARGETING IL-12/IL-23 P40 COMMON SUBUNIT WITH USTEKINUMAB, IL-17A WITH SECUKINUMAB AND IXEKIZUMAB, T CELLS CO-STIMULATION WITH ABATACEPT, IS NOW POSSIBLE, SAFE AND EFFECTIVE. MOREOVER, TARGETED SYNTHETIC MOLECULES WITH ORAL ADMINISTRATION ARE AVAILABLE, WITH THE POSSIBILITY TO INTERFERE WITH PHOSPHODIESTERASE-4 AND JAK/STAT PATHWAYS. INDEED, NEW DRUGS ARE UNDER DEVELOPMENT, WITH THE POSSIBILITY TO TARGET SELECTIVELY IL-17 RECEPTOR, IL-23, AND OTHER KEY MOLECULAR TARGETS IN THE PATHOGENESIS OF THIS CONDITION. IN THIS NARRATIVE REVIEW, WE PROVIDE AN UP-TO-DATE OVERVIEW OF THE CURRENT APPLICATION OF BIOLOGICAL AND TARGETED SYNTHETIC DMARDS IN THE FIELD OF PSA, WITH PARTICULAR REGARD TO THE CLINICAL SIGNIFICANCE OF THIS POSSIBILITY TO TARGET A HIGHER NUMBER OF DISTINCT IMMUNE-PATHWAYS. 2019 3 6617 29 UNDERPINNING THE NEUROBIOLOGICAL INTRICACIES ASSOCIATED WITH OPIOID TOLERANCE. THE OPIOID CRISIS IS A MAJOR THREAT OF THE 21ST CENTURY, WITH A REMARKABLE JUXTAPOSITION OF USE AND ABUSE. OPIOIDS ARE THE MOST POTENT AND EFFICACIOUS CLASS OF ANALGESICS, BUT DESPITE THEIR PROVEN THERAPEUTIC EFFICACY, THEY HAVE RECENTLY BEEN DEGRADED TO THIRD-LINE THERAPY FOR THE MANAGEMENT OF CHRONIC PAIN IN CLINICS. THE REASON BEHIND THIS IS THE DEVELOPMENT OF POTENTIAL SIDE EFFECTS AND TOLERANCE AFTER REPEATED DOSING. OPIOID TOLERANCE IS THE MAJOR LIMITING FACTOR LEADING TO THE WITHDRAWAL OF TREATMENT, SEVERE SIDE EFFECTS DUE TO DOSE ESCALATION, AND SOMETIMES EVEN DEATH OF THE PATIENTS. EVERY DAY MORE THAN 90 PEOPLE DIE DUE TO OPIOIDS OVERDOSE IN AMERICA, AND A SIMILAR TREND HAS BEEN SEEN ACROSS THE GLOBE. OVER THE PAST TWO DECADES, RESEARCHERS HAVE BEEN TRYING TO DISSECT THE NEUROBIOLOGICAL MECHANISM OF OPIOID TOLERANCE. RESEARCH ON OPIOID TOLERANCE SHIFTED TOWARD CENTRAL NERVOUS SYSTEM-BASED ADAPTATIONS BECAUSE TOLERANCE IS MUCH MORE THAN JUST A CELLULAR PHENOMENON. THUS, NEUROBIOLOGICAL ADAPTATIONS ASSOCIATED WITH OPIOID TOLERANCE ARE IMPORTANT TO UNDERSTAND IN ORDER TO FIND NEWER PAIN THERAPEUTICS. THESE ADAPTATIONS ARE ASSOCIATED WITH ALTERATIONS IN ASCENDING AND DESCENDING PAIN PATHWAYS, REWARD CIRCUITRY MODULATIONS, RECEPTOR DESENSITIZATION AND DOWN-REGULATION, RECEPTOR INTERNALIZATION, HETERODIMERIZATION, AND ALTERED EPIGENETIC REGULATION. THE PRESENT REVIEW IS FOCUSED ON NOVEL CIRCUITRIES ASSOCIATED WITH OPIOID TOLERANCE IN DIFFERENT AREAS OF THE BRAIN, SUCH AS PERIAQUEDUCTAL GRAY, ROSTRAL VENTROMEDIAL MEDULLA, DORSAL RAPHE NUCLEUS, VENTRAL TEGMENTAL AREA, AND NUCLEUS ACCUMBENS. UNDERSTANDING THE NEUROBIOLOGICAL MODULATIONS ASSOCIATED WITH CHRONIC OPIOID EXPOSURE AND TOLERANCE WILL PAVE THE WAY FOR THE DEVELOPMENT OF NOVEL PHARMACOLOGICAL TOOLS FOR SAFER AND BETTER MANAGEMENT OF CHRONIC PAIN IN PATIENTS. 2020 4 3186 51 HBV COVALENTLY CLOSED CIRCULAR DNA MINICHROMOSOMES IN DISTINCT EPIGENETIC TRANSCRIPTIONAL STATES DIFFER IN THEIR VULNERABILITY TO DAMAGE. BACKGROUND AND AIMS: HBV COVALENTLY CLOSED CIRCULAR DNA (CCCDNA) IS A MAJOR OBSTACLE FOR A CURE OF CHRONIC HEPATITIS B. ACCUMULATING EVIDENCE SUGGESTS THAT EPIGENETIC MODIFICATIONS REGULATE THE TRANSCRIPTIONAL ACTIVITY OF CCCDNA MINICHROMOSOMES. HOWEVER, IT REMAINS UNCLEAR HOW THE EPIGENETIC STATE OF CCCDNA AFFECTS ITS STABILITY. APPROACHES AND RESULTS: BY USING HBV INFECTION CELL MODELS AND IN VITRO AND IN VIVO RECOMBINANT CCCDNA (RCCCDNA) AND HBVCIRCLE MODELS, THE REDUCTION RATE OF HBV CCCDNA AND THE EFFICACY OF APOLIPOPROTEIN B MRNA EDITING ENZYME CATALYTIC SUBUNIT 3A (APOBEC3A)-MEDIATED AND CRISPR/CRISPR-ASSOCIATED 9 (CAS9)-MEDIATED CCCDNA TARGETING WERE COMPARED BETWEEN CCCDNAS WITH DISTINCT TRANSCRIPTIONAL ACTIVITIES. INTERFERON-ALPHA TREATMENT AND HEPATITIS B X PROTEIN (HBX) DELETION WERE APPLIED AS TWO STRATEGIES FOR CCCDNA REPRESSION. CHROMATIN IMMUNOPRECIPITATION AND MICROCOCCAL NUCLEASE ASSAYS WERE PERFORMED TO DETERMINE THE EPIGENETIC PATTERN OF CCCDNA. HBV CCCDNA LEVELS REMAINED STABLE IN NONDIVIDING HEPATOCYTES; HOWEVER, THEY WERE SIGNIFICANTLY REDUCED DURING CELL DIVISION, AND THE REDUCTION RATE WAS SIMILAR BETWEEN CCCDNAS IN TRANSCRIPTIONALLY ACTIVE AND TRANSCRIPTIONALLY REPRESSED STATES. STRIKINGLY, HBV RCCCDNA WITHOUT HBX EXPRESSION EXHIBITED A SIGNIFICANTLY LONGER PERSISTENCE IN MICE. THE CCCDNA WITH LOW TRANSCRIPTIONAL ACTIVITY EXHIBITED AN EPIGENETICALLY INACTIVE PATTERN AND WAS MORE DIFFICULT TO ACCESS BY APOBEC3A AND ENGINEERED CRISPR-CAS9. THE EPIGENETIC REGULATOR ACTIVATING CCCDNA INCREASED ITS VULNERABILITY TO APOBEC3A. CONCLUSIONS: HBV CCCDNA MINICHROMOSOMES IN DISTINCT EPIGENETIC TRANSCRIPTIONAL STATES SHOWED A SIMILAR REDUCTION RATE DURING CELL DIVISION BUT SIGNIFICANTLY DIFFERED IN THEIR ACCESSIBILITY AND VULNERABILITY TO TARGETED NUCLEASES AND ANTIVIRAL AGENTS. EPIGENETIC SENSITIZATION OF CCCDNA MAKES IT MORE SUSCEPTIBLE TO DAMAGE AND MAY POTENTIALLY CONTRIBUTE TO AN HBV CURE. 2022 5 5365 24 RECENT ADVANCES IN HEPATITIS B TREATMENT. HEPATITIS B VIRUS INFECTION AFFECTS OVER 250 MILLION CHRONIC CARRIERS, CAUSING MORE THAN 800,000 DEATHS ANNUALLY, ALTHOUGH A SAFE AND EFFECTIVE VACCINE IS AVAILABLE. CURRENTLY USED ANTIVIRAL AGENTS, PEGYLATED INTERFERON AND NUCLEOS(T)IDE ANALOGUES, HAVE MAJOR DRAWBACKS AND FAIL TO COMPLETELY ERADICATE THE VIRUS FROM INFECTED CELLS. THUS, ACHIEVING A "FUNCTIONAL CURE" OF THE INFECTION REMAINS A REAL CHALLENGE. RECENT FINDINGS CONCERNING THE VIRAL REPLICATION CYCLE HAVE LED TO DEVELOPMENT OF NOVEL THERAPEUTIC APPROACHES INCLUDING VIRAL ENTRY INHIBITORS, EPIGENETIC CONTROL OF CCCDNA, IMMUNE MODULATORS, RNA INTERFERENCE TECHNIQUES, RIBONUCLEASE H INHIBITORS, AND CAPSID ASSEMBLY MODULATORS. PROMISING PRECLINICAL RESULTS HAVE BEEN OBTAINED, AND THE LEADING MOLECULES UNDER DEVELOPMENT HAVE ENTERED CLINICAL EVALUATION. THIS REVIEW SUMMARIZES THE KEY STEPS OF THE HBV LIFE CYCLE, EXAMINES THE CURRENTLY APPROVED ANTI-HBV DRUGS, AND ANALYZES NOVEL HBV TREATMENT REGIMENS. 2021 6 4055 47 MAPPING OF HISTONE MODIFICATIONS IN EPISOMAL HBV CCCDNA UNCOVERS AN UNUSUAL CHROMATIN ORGANIZATION AMENABLE TO EPIGENETIC MANIPULATION. CHRONIC HEPATITIS B VIRUS (HBV) INFECTION AFFECTS 240 MILLION PEOPLE WORLDWIDE AND IS A MAJOR RISK FACTOR FOR LIVER FAILURE AND HEPATOCELLULAR CARCINOMA. CURRENT ANTIVIRAL THERAPY INHIBITS CYTOPLASMIC HBV GENOMIC REPLICATION, BUT IS NOT CURATIVE BECAUSE IT DOES NOT DIRECTLY AFFECT NUCLEAR HBV CLOSED CIRCULAR DNA (CCCDNA), THE GENOMIC FORM THAT TEMPLATES VIRAL TRANSCRIPTION AND SUSTAINS VIRAL PERSISTENCE. NOVEL APPROACHES THAT DIRECTLY TARGET CCCDNA REGULATION WOULD THEREFORE BE HIGHLY DESIRABLE. CCCDNA IS ASSEMBLED WITH CELLULAR HISTONE PROTEINS INTO CHROMATIN, BUT LITTLE IS KNOWN ABOUT THE REGULATION OF HBV CHROMATIN BY HISTONE POSTTRANSLATIONAL MODIFICATIONS (PTMS). HERE, USING A NEW CCCDNA CHIP-SEQ APPROACH, WE REPORT, TO OUR KNOWLEDGE, THE FIRST GENOME-WIDE MAPS OF PTMS IN CCCDNA-CONTAINING CHROMATIN FROM DE NOVO INFECTED HEPG2 CELLS, PRIMARY HUMAN HEPATOCYTES, AND FROM HBV-INFECTED LIVER TISSUE. WE FIND HIGH LEVELS OF PTMS ASSOCIATED WITH ACTIVE TRANSCRIPTION ENRICHED AT SPECIFIC SITES WITHIN THE HBV GENOME AND, SURPRISINGLY, VERY LOW LEVELS OF PTMS LINKED TO TRANSCRIPTIONAL REPRESSION EVEN AT SILENT HBV PROMOTERS. WE SHOW THAT TRANSCRIPTION AND ACTIVE PTMS IN HBV CHROMATIN ARE REDUCED BY THE ACTIVATION OF AN INNATE IMMUNITY PATHWAY, AND THAT THIS EFFECT CAN BE RECAPITULATED WITH A SMALL MOLECULE EPIGENETIC MODIFYING AGENT, OPENING THE POSSIBILITY THAT CHROMATIN-BASED REGULATION OF CCCDNA TRANSCRIPTION COULD BE A NEW THERAPEUTIC APPROACH TO CHRONIC HBV INFECTION. 2015 7 5368 31 RECENT ADVANCES IN THE STUDY OF HEPATITIS B VIRUS COVALENTLY CLOSED CIRCULAR DNA. CHRONIC HEPATITIS B INFECTION IS CAUSED BY HEPATITIS B VIRUS (HBV) AND A TOTAL CURE IS YET TO BE ACHIEVED. THE VIRAL COVALENTLY CLOSED CIRCULAR DNA (CCCDNA) IS THE KEY TO ESTABLISH A PERSISTENT INFECTION WITHIN HEPATOCYTES. CURRENT ANTIVIRAL STRATEGIES HAVE NO EFFECT ON THE PRE-EXISTING CCCDNA RESERVOIR. THEREFORE, THE STUDY OF THE MOLECULAR MECHANISM OF CCCDNA FORMATION IS BECOMING A MAJOR FOCUS OF HBV RESEARCH. THIS REVIEW SUMMARIZES THE CURRENT ADVANCES IN CCCDNA MOLECULAR BIOLOGY AND THE LATEST STUDIES ON THE ELIMINATION OR INACTIVATION OF CCCDNA, INCLUDING THREE MAJOR AREAS: (1) EPIGENETIC REGULATION OF CCCDNA BY HBV X PROTEIN, (2) IMMUNE-MEDIATED DEGRADATION, AND (3) GENOME-EDITING NUCLEASES. ALL THESE ASPECTS PROVIDE CLUES ON HOW TO FINALLY ATTAIN A CURE FOR CHRONIC HEPATITIS B INFECTION. 2017 8 3380 40 HIV-1 INFECTION OF GENETICALLY ENGINEERED IPSC-DERIVED CENTRAL NERVOUS SYSTEM-ENGRAFTED MICROGLIA IN A HUMANIZED MOUSE MODEL. THE CENTRAL NERVOUS SYSTEM (CNS) IS A MAJOR HUMAN IMMUNODEFICIENCY VIRUS TYPE 1 RESERVOIR. MICROGLIA ARE THE PRIMARY TARGET CELL OF HIV-1 INFECTION IN THE CNS. CURRENT MODELS HAVE NOT ALLOWED THE PRECISE MOLECULAR PATHWAYS OF ACUTE AND CHRONIC CNS MICROGLIAL INFECTION TO BE TESTED WITH IN VIVO GENETIC METHODS. HERE, WE DESCRIBE A NOVEL HUMANIZED MOUSE MODEL UTILIZING HUMAN-INDUCED PLURIPOTENT STEM CELL-DERIVED MICROGLIA TO XENOGRAFT INTO MURINE HOSTS. THESE MICE ARE ADDITIONALLY ENGRAFTED WITH HUMAN PERIPHERAL BLOOD MONONUCLEAR CELLS THAT SERVED AS A MEDIUM TO ESTABLISH A PERIPHERAL INFECTION THAT THEN SPREAD TO THE CNS MICROGLIA XENOGRAFT, MODELING A TRANS-BLOOD-BRAIN BARRIER ROUTE OF ACUTE CNS HIV-1 INFECTION WITH HUMAN TARGET CELLS. THE APPROACH IS COMPATIBLE WITH IPSC GENETIC ENGINEERING, INCLUDING INSERTING TARGETED TRANSGENIC REPORTER CASSETTES TO TRACK THE XENOGRAFTED HUMAN CELLS, ENABLING THE TESTING OF NOVEL TREATMENT AND VIRAL TRACKING STRATEGIES IN A COMPARATIVELY SIMPLE AND COST-EFFECTIVE WAY VIVO MODEL FOR NEUROHIV. IMPORTANCE: OUR MOUSE MODEL IS A POWERFUL TOOL FOR INVESTIGATING THE GENETIC MECHANISMS GOVERNING CNS HIV-1 INFECTION AND LATENCY IN THE CNS AT A SINGLE-CELL LEVEL. A MAJOR ADVANTAGE OF OUR MODEL IS THAT IT USES IPSC-DERIVED MICROGLIA, WHICH ENABLES HUMAN GENETICS, INCLUDING GENE FUNCTION AND THERAPEUTIC GENE MANIPULATION, TO BE EXPLORED IN VIVO , WHICH IS MORE CHALLENGING TO STUDY WITH CURRENT HEMATOPOIETIC STEM CELL-BASED MODELS FOR NEUROHIV. OUR TRANSGENIC TRACING OF XENOGRAFTED HUMAN CELLS WILL PROVIDE A QUANTITATIVE MEDIUM TO DEVELOP NEW MOLECULAR AND EPIGENETIC STRATEGIES FOR REDUCING THE HIV-1 LATENT RESERVOIR AND TO TEST THE IMPACT OF THERAPEUTIC INFLAMMATION-TARGETING DRUG INTERVENTIONS ON CNS HIV-1 LATENCY. 2023 9 5952 42 TARGETING VIRAL CCCDNA FOR CURE OF CHRONIC HEPATITIS B. PURPOSE OF REVIEW: CHRONIC HEPATITIS B (CHB), CAUSED BY HEPATITIS B VIRUS (HBV), IS A MAJOR CAUSE OF ADVANCED LIVER DISEASE AND HEPATOCELLULAR CARCINOMA (HCC) WORLDWIDE. HBV REPLICATION IS CHARACTERIZED BY THE SYNTHESIS OF COVALENTLY CLOSED CIRCULAR (CCC) DNA WHICH IS NOT TARGETED BY ANTIVIRAL NUCLEOS(T)IDE ANALOGUES (NUCS) THE KEY MODALITY OF STANDARD OF CARE. WHILE HBV REPLICATION IS SUCCESSFULLY SUPPRESSED IN TREATED PATIENTS, THEY REMAIN AT RISK FOR DEVELOPING HCC. WHILE FUNCTIONAL CURE, CHARACTERIZED BY LOSS OF HBSAG, IS THE FIRST GOAL OF NOVEL ANTIVIRAL THERAPIES, CURATIVE TREATMENTS ELIMINATING CCCDNA REMAIN THE ULTIMATE GOAL. THIS REVIEW SUMMARIZES RECENT ADVANCES IN THE DISCOVERY AND DEVELOPMENT OF NOVEL THERAPEUTIC STRATEGIES AND THEIR IMPACT ON CCCDNA BIOLOGY. RECENT FINDINGS: WITHIN THE LAST DECADE, SUBSTANTIAL PROGRESS HAS BEEN MADE IN THE UNDERSTANDING OF CCCDNA BIOLOGY INCLUDING THE DISCOVERY OF HOST DEPENDENCY FACTORS, EPIGENETIC REGULATION OF CCCDNA TRANSCRIPTION AND IMMUNE-MEDIATED DEGRADATION. SEVERAL APPROACHES TARGETING CCCDNA EITHER IN A DIRECT OR INDIRECT MANNER ARE CURRENTLY AT THE STAGE OF DISCOVERY, PRECLINICAL OR EARLY CLINICAL DEVELOPMENT. EXAMPLES INCLUDE GENOME-EDITING APPROACHES, STRATEGIES TARGETING HOST DEPENDENCY FACTORS OR EPIGENETIC GENE REGULATION, NUCLEOCAPSID MODULATORS AND IMMUNE-MEDIATED DEGRADATION. SUMMARY: WHILE DIRECT-TARGETING CCCDNA STRATEGIES ARE STILL LARGELY AT THE PRECLINICAL STAGE OF DEVELOPMENT, CAPSID ASSEMBLY MODULATORS AND IMMUNE-BASED APPROACHES HAVE REACHED THE CLINICAL PHASE. CLINICAL TRIALS ARE ONGOING TO ASSESS THEIR EFFICACY AND SAFETY IN PATIENTS INCLUDING THEIR IMPACT ON VIRAL CCCDNA. COMBINATION THERAPIES PROVIDE ADDITIONAL OPPORTUNITIES TO OVERCOME CURRENT LIMITATIONS OF INDIVIDUAL APPROACHES. 2020 10 6479 41 TOWARD A NEW ERA OF HEPATITIS B VIRUS THERAPEUTICS: THE PURSUIT OF A FUNCTIONAL CURE. HEPATITIS B VIRUS (HBV) INFECTION, ALTHOUGH PREVENTABLE BY VACCINATION, REMAINS A GLOBAL HEALTH PROBLEM AND A MAJOR CAUSE OF CHRONIC LIVER DISEASE. ALTHOUGH CURRENT TREATMENT STRATEGIES SUPPRESS VIRAL REPLICATION VERY EFFICIENTLY, THE OPTIMAL ENDPOINT OF HEPATITIS B SURFACE ANTIGEN (HBSAG) CLEARANCE IS RARELY ACHIEVED. MOREOVER, THE THORNY PROBLEMS OF PERSISTENT CHROMATIN-LIKE COVALENTLY CLOSED CIRCULAR DNA AND THE PRESENCE OF INTEGRATED HBV DNA IN THE HOST GENOME ARE IGNORED. THEREFORE, THE SCIENTIFIC COMMUNITY HAS FOCUSED ON DEVELOPING INNOVATIVE THERAPEUTIC APPROACHES TO ACHIEVE A FUNCTIONAL CURE OF HBV, DEFINED AS UNDETECTABLE HBV DNA AND HBSAG LOSS OVER A LIMITED TREATMENT PERIOD. A DEEPER UNDERSTANDING OF THE HBV LIFE CYCLE HAS LED TO THE INTRODUCTION OF NOVEL DIRECT-ACTING ANTIVIRALS THAT EXERT THEIR FUNCTION THROUGH MULTIPLE MECHANISMS, INCLUDING INHIBITION OF VIRAL ENTRY, TRANSCRIPTIONAL SILENCING, EPIGENETIC MANIPULATION, INTERFERENCE WITH CAPSID ASSEMBLY, AND DISRUPTION OF HBSAG RELEASE. IN PARALLEL, ANOTHER CATEGORY OF NEW DRUGS AIMS TO RESTORE DYSREGULATED IMMUNE FUNCTION IN CHRONIC HEPATITIS B ACCOMPANIED BY LETHARGIC CELLULAR AND HUMORAL RESPONSES. STIMULATION OF INNATE IMMUNITY BY PATTERN-RECOGNITION RECEPTOR AGONISTS LEADS TO UPREGULATION OF ANTIVIRAL CYTOKINE EXPRESSION AND APPEARS TO CONTRIBUTE TO HBV CONTAINMENT. IMMUNE CHECKPOINT INHIBITORS AND ADOPTIVE TRANSFER OF GENETICALLY ENGINEERED T CELLS ARE BREAKTHROUGH TECHNOLOGIES CURRENTLY BEING EXPLORED THAT MAY ELICIT POTENT HBV-SPECIFIC T-CELL RESPONSES. IN ADDITION, SEVERAL CLINICAL TRIALS ARE ATTEMPTING TO CLARIFY THE ROLE OF THERAPEUTIC VACCINATION IN THIS SETTING. ULTIMATELY, IT IS INCREASINGLY RECOGNIZED THAT ELIMINATION OF HBV REQUIRES A TREATMENT REGIMEN BASED ON A COMBINATION OF MULTIPLE DRUGS. THIS REVIEW DESCRIBES THE RATIONALE FOR PROGRESSIVE THERAPEUTIC INTERVENTIONS AND DISCUSSES THE LATEST FINDINGS IN THE FIELD OF HBV THERAPEUTICS. 2021 11 4848 33 OPIOID-INDUCED STRUCTURAL AND FUNCTIONAL PLASTICITY OF MEDIUM-SPINY NEURONS IN THE NUCLEUS ACCUMBENS. OPIOID USE DISORDER (OUD) IS A CHRONIC RELAPSING CLINICAL CONDITION WITH TREMENDOUS MORBIDITY AND MORTALITY THAT FREQUENTLY PERSISTS, DESPITE TREATMENT, DUE TO AN INDIVIDUAL'S UNDERLYING PSYCHOLOGICAL, NEUROBIOLOGICAL, AND GENETIC VULNERABILITIES. EVIDENCE SUGGESTS THAT THESE VULNERABILITIES MAY HAVE NEUROCHEMICAL, CELLULAR, AND MOLECULAR BASES. KEY NEUROPLASTIC EVENTS WITHIN THE MESOCORTICOLIMBIC SYSTEM THAT EMERGE THROUGH CHRONIC EXPOSURE TO OPIOIDS MAY HAVE A DETERMINATIVE INFLUENCE ON BEHAVIORAL SYMPTOMS ASSOCIATED WITH OUD. IN PARTICULAR, STRUCTURAL AND FUNCTIONAL ALTERATIONS IN THE DENDRITIC SPINES OF MEDIUM SPINY NEURONS (MSNS) WITHIN THE NUCLEUS ACCUMBENS (NAC) AND ITS DOPAMINERGIC PROJECTIONS FROM THE VENTRAL TEGMENTAL AREA (VTA) ARE BELIEVED TO FACILITATE THESE BEHAVIORAL SEQUELAE. ADDITIONALLY, GLUTAMATERGIC NEURONS FROM THE PREFRONTAL CORTEX, THE BASOLATERAL AMYGDALA, THE HIPPOCAMPUS, AND THE THALAMUS PROJECT TO THESE SAME MSNS, PROVIDING AN ENRICHED TARGET FOR SYNAPTIC PLASTICITY. HERE, WE REVIEW LITERATURE RELATED TO NEUROADAPTATIONS IN NAC MSNS FROM DOPAMINERGIC AND GLUTAMATERGIC PATHWAYS IN OUD. WE ALSO DESCRIBE NEW FINDINGS RELATED TO TRANSCRIPTIONAL, EPIGENETIC, AND MOLECULAR MECHANISMS IN MSN PLASTICITY IN THE DIFFERENT STAGES OF OUD. 2021 12 3794 42 INTERLEUKIN-33 MEDIATES BOTH IMMUNE-RELATED AND NON-IMMUNE-RELATED INHIBITORY EFFECTS AGAINST HEPATITIS B VIRUS. CHRONIC INFECTION BY HEPATITIS B VIRUS (HBV) IS ASSOCIATED WITH HIGH RISKS OF LIVER FIBROSIS, CIRRHOSIS AND HEPATOCELLULAR CARCINOMA. HBV COVALENTLY CLOSED CIRCULAR DNA (CCCDNA) IN THE NUCLEUS OF INFECTED HEPATOCYTE SERVES AS TRANSCRIPTION TEMPLATE. NEITHER NATURAL RESOLUTION OF ACUTE INFECTION NOR CURRENT TREATMENT OPTIONS FOR CHRONIC INFECTION ARE BELIEVED TO CAUSE CCCDNA CLEARANCE. WE PREVIOUSLY SHOWED THAT INJECTION OF IL-33-EXPRESSING PLASMID FACILITATED CLEARANCE OF INTRAHEPATIC HBV DNA IN A MOUSE MODEL OF HBV PERSISTENCE. IN THIS WORK, HBV-TARGETING THERAPEUTIC EFFECTS OF IL-33 WERE FURTHER EXPLORED. MURINE IL-33 DELIVERED BY RECOMBINANT ADENO-ASSOCIATED VIRUS (AAV-MIL-33) INDUCED CLEARANCE OF BOTH SERUM HBV MARKERS AND INTRAHEPATIC HBV DNA IN TWO MOUSE MODELS OF HBV PERSISTENCE BASED ON REPLICON PLASMID AND RECOMBINANT CCCDNA (RCCCDNA) RESPECTIVELY. CLEARANCE WAS ASSOCIATED WITH SERUM ALT ELEVATIONS AND LIVER INFILTRATIONS BY CD4(+) AND CD8(+) T CELLS, INDICATING IL-33-INDUCED CELLULAR IMMUNE RESPONSES AGAINST HBV-HARBORING CELLS. ADOPTIVE TRANSFER OF SPLENOCYTES FROM AAV-MIL-33-CURED MICE WAS INDEED SUFFICIENT TO ENGENDER SIMILAR CLEARANCE IN RECIPIENT MICE. IN VITRO, INTRACELLULAR, INSTEAD OF EXTRACELLULAR, IL-33 WAS MAINLY RESPONSIBLE FOR REPRESSING VIRAL TRANSCRIPTION, PROTEIN PRODUCTION AND GENOME REPLICATION IN HUH7 CELLS TRANSFECTED WITH HBV REPLICON OR RCCCDNA. IL-33 WAS SHOWN TO BE RECRUITED ONTO RCCCDNA MINICHROMOSOME ACCOMPANIED BY LOSS OF TRANSCRIPTIONAL ACTIVATION EPIGENETIC MARKS. FINALLY, TRANSFECTION OF IL-33 INTO HBV-INFECTED HEPG2/NTCP CELLS RESULTED IN REDUCED TRANSCRIPTION, ANTIGEN EXPRESSION AND GENOME REPLICATION, SUGGESTING REPRESSION OF CANONICAL CCCDNA. THESE DATA DEMONSTRATED DIVERSE INHIBITORY EFFECTS ON HBV AND HBV-INFECTED CELLS MEDIATED BY IL-33, AND SUGGEST IL-33 AS AN INTERESTING THERAPEUTIC CANDIDATE. 2022 13 2915 39 GENE THERAPY FOR CHRONIC HBV-CAN WE ELIMINATE CCCDNA? CHRONIC INFECTION WITH THE HEPATITIS B VIRUS (HBV) IS A GLOBAL HEALTH CONCERN AND ACCOUNTS FOR APPROXIMATELY 1 MILLION DEATHS ANNUALLY. AMONGST OTHER LIMITATIONS OF CURRENT ANTI-HBV TREATMENT, FAILURE TO ELIMINATE THE VIRAL COVALENTLY CLOSED CIRCULAR DNA (CCCDNA) AND EMERGENCE OF RESISTANCE REMAIN THE MOST WORRISOME. VIRAL REBOUND FROM LATENT EPISOMAL CCCDNA RESERVOIRS OCCURS FOLLOWING CESSATION OF THERAPY, PATIENT NON-COMPLIANCE, OR THE DEVELOPMENT OF ESCAPE MUTANTS. SIMULTANEOUS VIRAL CO-INFECTIONS, SUCH AS BY HIV-1, FURTHER COMPLICATE THERAPEUTIC INTERVENTIONS. THESE CHALLENGES HAVE PROMPTED DEVELOPMENT OF NOVEL TARGETED HEPATITIS B THERAPIES. GIVEN THE EASE WITH WHICH HIGHLY SPECIFIC AND POTENT NUCLEIC ACID THERAPEUTICS CAN BE RATIONALLY DESIGNED, GENE THERAPY HAS GENERATED INTEREST FOR ANTIVIRAL APPLICATION. GENE THERAPY STRATEGIES DEVELOPED FOR HBV INCLUDE GENE SILENCING BY HARNESSING RNA INTERFERENCE, TRANSCRIPTIONAL INHIBITION THROUGH EPIGENETIC MODIFICATION OF TARGET DNA, GENOME EDITING BY DESIGNER NUCLEASES, AND IMMUNE MODULATION WITH CYTOKINES. DNA-BINDING DOMAINS AND EFFECTORS BASED ON THE ZINC FINGER (ZF), TRANSCRIPTION ACTIVATOR-LIKE EFFECTOR (TALE), AND CLUSTERED REGULARLY INTERSPACED SHORT PALINDROMIC REPEAT (CRISPR) SYSTEMS ARE REMARKABLY WELL SUITED TO TARGETING EPISOMAL CCCDNA. THIS REVIEW DISCUSSES RECENT DEVELOPMENTS AND CHALLENGES FACING THE FIELD OF ANTI-HBV GENE THERAPY, ITS POTENTIAL CURATIVE SIGNIFICANCE AND THE PROGRESS TOWARDS CLINICAL APPLICATION. 2018 14 4816 35 OCCULT HEPATITIS B VIRUS INFECTION: A COMPLEX ENTITY WITH RELEVANT CLINICAL IMPLICATIONS. OCCULT HEPATITIS B VIRUS (HBV) INFECTION IS A WORLD-WIDE ENTITY, FOLLOWING THE GEOGRAPHICAL DISTRIBUTION OF DETECTABLE HEPATITIS B. THIS ENTITY IS DEFINED AS THE PERSISTENCE OF VIRAL GENOMES IN THE LIVER TISSUE AND IN SOME INSTANCES ALSO IN THE SERUM, ASSOCIATED TO NEGATIVE HBV SURFACE ANTIGEN SEROLOGY. THE MOLECULAR BASIS OF THE OCCULT INFECTION IS RELATED TO THE LIFE CYCLE OF HBV, WHICH PRODUCES A COVALENTLY CLOSED CIRCULAR DNA THAT PERSISTS IN THE CELL NUCLEI AS AN EPISOME, AND SERVES AS A TEMPLATE FOR GENE TRANSCRIPTION. THE MECHANISM RESPONSIBLE FOR THE HBSAG NEGATIVE STATUS IN OCCULT HBV CARRIERS IS A STRONG SUPPRESSION OF VIRAL REPLICATION, PROBABLY DUE TO THE HOST'S IMMUNE RESPONSE, CO-INFECTION WITH OTHER INFECTIOUS AGENTS AND EPIGENETIC FACTORS. THERE IS EMERGING EVIDENCE OF THE POTENTIAL CLINICAL RELEVANCE OF OCCULT HBV INFECTION, SINCE THIS COULD BE INVOLVED IN OCCULT HBV TRANSMISSION THROUGH ORTHOTOPIC LIVER TRANSPLANT AND BLOOD TRANSFUSION, REACTIVATION OF HBV INFECTION DURING IMMUNOSUPPRESSION, IMPAIRING CHRONIC LIVER DISEASE OUTCOME AND ACTING AS A RISK FACTOR FOR HEPATOCELLULAR CARCINOMA. THEREFORE IT IS IMPORTANT TO BEAR IN MIND THIS ENTITY IN CRYPTOGENETIC LIVER DISEASES, HEPATITIS C VIRUS/HIV INFECTED PATIENTS AND IMMUNOSUPRESSED INDIVIDUALS. IT IS ALSO NECESSARY TO INCREASE OUR KNOWLEDGE IN THIS FASCINATING FIELD TO DEFINE BETTER STRATEGIES TO DIAGNOSE AND TREAT THIS INFECTION. 2011 15 5689 43 SILENCING HEPATITIS B VIRUS COVALENTLY CLOSED CIRCULAR DNA: THE POTENTIAL OF AN EPIGENETIC THERAPY APPROACH. GLOBAL PROPHYLACTIC VACCINATION PROGRAMMES HAVE HELPED TO CURB NEW HEPATITIS B VIRUS (HBV) INFECTIONS. HOWEVER, IT IS ESTIMATED THAT NEARLY 300 MILLION PEOPLE ARE CHRONICALLY INFECTED AND HAVE A HIGH RISK OF DEVELOPING HEPATOCELLULAR CARCINOMA. AS SUCH, HBV REMAINS A SERIOUS HEALTH PRIORITY AND THE DEVELOPMENT OF NOVEL CURATIVE THERAPEUTICS IS URGENTLY NEEDED. CHRONIC HBV INFECTION HAS BEEN ATTRIBUTED TO THE PERSISTENCE OF THE COVALENTLY CLOSED CIRCULAR DNA (CCCDNA) WHICH ESTABLISHES ITSELF AS A MINICHROMOSOME IN THE NUCLEUS OF HEPATOCYTES. AS THE VIRAL TRANSCRIPTION INTERMEDIATE, THE CCCDNA IS RESPONSIBLE FOR PRODUCING NEW VIRIONS AND PERPETUATING INFECTION. HBV IS DEPENDENT ON VARIOUS HOST FACTORS FOR CCCDNA FORMATION AND THE MINICHROMOSOME IS AMENABLE TO EPIGENETIC MODIFICATIONS. TWO HBV PROTEINS, X (HBX) AND CORE (HBC) PROMOTE VIRAL REPLICATION BY MODULATING THE CCCDNA EPIGENOME AND REGULATING HOST CELL RESPONSES. THIS INCLUDES VIRAL AND HOST GENE EXPRESSION, CHROMATIN REMODELING, DNA METHYLATION, THE ANTIVIRAL IMMUNE RESPONSE, APOPTOSIS, AND UBIQUITINATION. ELIMINATION OF THE CCCDNA MINICHROMOSOME WOULD RESULT IN A STERILIZING CURE; HOWEVER, THIS MAY BE DIFFICULT TO ACHIEVE. EPIGENETIC THERAPIES COULD PERMANENTLY SILENCE THE CCCDNA MINICHROMOSOME AND PROMOTE A FUNCTIONAL CURE. THIS REVIEW EXPLORES THE CCCDNA EPIGENOME, HOW HOST AND VIRAL FACTORS INFLUENCE TRANSCRIPTION, AND THE RECENT EPIGENETIC THERAPIES AND EPIGENOME ENGINEERING APPROACHES THAT HAVE BEEN DESCRIBED. 2021 16 4756 35 NOVEL THERAPEUTIC TARGET(S) FOR PSORIATIC DISEASE. PSORIASIS AND PSORIATIC ARTHRITIS, TOGETHER KNOWN AS PSORIATIC DISEASE, IS HIGHLY PREVALENT CHRONIC RELAPSING INFLAMMATORY DISEASE AFFECTING SKIN, JOINTS OR BOTH AND IS ASSOCIATED WITH SEVERAL COMORBIDITIES SUCH AS CARDIOVASCULAR, METABOLIC, PSYCHIATRIC, RENAL DISEASE ETC. THE ETIOPATHOGENESIS OF PSORIASIS IS COMPLEX AND MAINLY DRIVEN BY ABERRANT IMMUNE RESPONSE OWING TO THE GENETIC SUSCEPTIBILITY AND VARIOUS ENVIRONMENTAL FACTORS SUCH AS TRAUMA, INFECTIONS AND DRUGS. RECENT ADVANCES IN UNDERSTANDING MOLECULAR AND CELLULAR PATHWAYS HAVE IDENTIFIED TUMOR NECROSIS FACTOR-ALPHA (TNF-ALPHA), INTERLEUKIN-17 (IL-17), IL-23, IL-22 AS MAJOR CONTRIBUTORS IN PSORIASIS PATHOGENESIS. ADVANCES IN THE KNOWLEDGE OF PATHOPHYSIOLOGY, THE INTERACTION OF AUTOINFLAMMATION AND CLINICAL PHENOTYPES HAVE LED TO THE DEVELOPMENT OF HIGHLY EFFECTIVE TARGETED THERAPEUTIC AGENTS WHICH INCLUDE TNF-ALPHA, IL-17, IL-23, IL-1 ALPHA/BETA OR IL-36 INHIBITORS OR RECEPTOR BLOCKERS, SMALL MOLECULE DRUGS LIKE PHOSPHODIESTERASE-4 INHIBITORS (APREMILAST), JANUS KINASE (JAK) INHIBITORS, RETINOIC ACID RECEPTOR-RELATED ORPHAN RECEPTOR GAMMAT (RORGAMMAT) INHIBITORS. THESE NOVEL DRUGS HAVE PROMISED THE POTENTIAL OF IMPROVED DISEASE CONTROL. IN RECENT YEARS, THE TRANSITION FROM BIOLOGICS TO BIOSIMILARS ESPECIALLY WITH TNF-ALPHA INHIBITORS HAD SIGNIFICANT IMPACT ON DECREASING HEALTH CARE COST AND INCREASING THERAPEUTIC OPTIONS TO THE PATIENTS. HOWEVER, SELECTION OF RIGHT TREATMENT FOR AN INDIVIDUAL PATIENT STILL REMAINS CHALLENGING. MOREOVER, INTERPLAY BETWEEN DIFFERENT EPIGENETIC MECHANISMS SUCH AS THE DNA METHYLATION, CHROMATIN MODIFICATIONS AND NONCODING RNA REGULATION HAS RECENTLY BEEN STARTED TO BE DECIPHERED. ENZYMES INHIBITORS INVOLVED IN EPIGENETIC PATHWAYS SUCH AS DNA METHYLTRANSFERASES AND HISTONE DEACETYLASES DEMONSTRATED TO RESTORE NORMAL EPIGENETIC PATTERNS IN CLINICAL SETTINGS AND HAVE PROVIDED THE POTENTIAL AS NOVEL THERAPEUTIC TARGETS FOR PSORIASIS. IN THIS REVIEW, WE WILL DISCUSS NOVEL BIOLOGIC AGENTS AND NEWER THERAPEUTIC APPROACHES IN TREATMENT OF PSORIATIC DISEASE. 2022 17 3782 48 INTERFERON THERAPY OF CHRONIC HEPATITIS B. CHRONIC HEPATITIS B (CHB) RESULTS FROM THE INABILITY OF THE HOST'S IMMUNE SYSTEM TO CONTROL VIRAL REPLICATION. INTERFERON-ALPHA (IFN-ALPHA) THERAPY CAN CONVERT CHB INTO INACTIVE HEPATITIS B VIRUS (HBV) INFECTION IN 20-30% OF THE TREATED PATIENTS. IN SPITE OF THE LOW RESPONSE RATE, IFN-ALPHA THERAPY HAS THE ADVANTAGE OF HAVING A LIMITED DURATION AND BEING EFFECTIVE EVEN AFTER THERAPY, AS DEMONSTRATED BY A MUCH HIGHER INCIDENCE OF HBSAG CLEARANCE IN RESPONDERS TO IFN-ALPHA THAN IN NATURALLY OCCURRING INACTIVE HBSAG CARRIERS. IFN-ALPHA HAS MULTIPLE ANTIVIRAL, ANTIPROLIFERATIVE, AND IMMUNOMODULATORY ACTIVITIES AND TARGETS: CELLULAR GENES (IFN-STIMULATED GENES) ACTIVATING DIFFERENT PATHWAYS OF ANTIVIRAL DEFENSE IN INFECTED AND NONINFECTED CELLS, HBV REPLICATION BLOCKING THE RNA-CONTAINING CORE PARTICLE FORMATION AND ACCELERATING THEIR DECAY, DEGRADING PREGENOMIC RNA, AND MODULATING THE NUCLEAR VIRAL MINICHROMOSOME (COVALENTLY CLOSED CIRCULAR DNA) ACTIVITY BY TARGETING ITS EPIGENETIC REGULATION AND BOTH INNATE AND ADAPTIVE IMMUNE RESPONSE. THE INTERFERENCE OF VIRAL HETEROGENEITY AND GENETIC POLYMORPHISMS OF THE HOST ON IFN-ALPHA SUSCEPTIBILITY IS UNDER INVESTIGATION. ONLY A BETTER UNDERSTANDING OF THE COMPLEX INTERPLAY BETWEEN THE DIFFERENT ACTIVITIES OF IFN-ALPHA WOULD WARRANT THE AMELIORATION OF CURRENT THERAPEUTIC STRATEGIES AND THE DESIGN OF NEW THERAPEUTIC APPROACHES. THE STUDY OF ON-TREATMENT DYNAMICS OF HBV INFECTION BY MEANS OF COMBINED QUANTITATIVE MONITORING OF SERUM HBV DNA AND HBSAG WARRANT TAILORING TREATMENT AT THE SINGLE-PATIENT LEVEL AND CAN HELP TO MAKE TREATMENT MORE COST-EFFECTIVE BY USING THE DIFFERENT COMBINATIONS OF CURRENTLY AVAILABLE ANTIVIRALS, INCLUDING IFN, MORE APPROPRIATELY. INTEGRATED MOLECULAR AND CLINICAL KNOWLEDGE IN A SYSTEMS MEDICINE FASHION IS MANDATORY TO FURTHER IMPROVE ANTIVIRAL THERAPY IN CHB. 2014 18 2324 35 EPIGENETIC REGULATION OF HEPATITIS B VIRUS COVALENTLY CLOSED CIRCULAR DNA: IMPLICATIONS FOR EPIGENETIC THERAPY AGAINST CHRONIC HEPATITIS B. HEPATITIS B VIRUS (HBV) INFECTION REPRESENTS A SIGNIFICANT PUBLIC HEALTH BURDEN WORLDWIDE. ALTHOUGH CURRENT THERAPEUTICS MANAGE TO CONTROL THE DISEASE PROGRESSION, LIFELONG TREATMENT AND SURVEILLANCE ARE REQUIRED BECAUSE DRUG RESISTANCE DEVELOPS DURING TREATMENT AND REACTIVATIONS FREQUENTLY OCCUR FOLLOWING MEDICATION CESSATION. THUS, THE OCCURRENCE OF HEPATOCELLULAR CARCINOMA IS DECREASED, BUT NOT ELIMINATED. ONE MAJOR REASON FOR FAILURE OF HBV TREATMENT IS THE INABILITY TO ERADICATE OR INACTIVATE THE VIRAL COVALENTLY CLOSED CIRCULAR DNA (CCCDNA), WHICH IS A STABLE EPISOMAL FORM OF THE VIRAL GENOME DECORATED WITH HOST HISTONES AND NONHISTONE PROTEINS. ACCUMULATING EVIDENCE SUGGESTS THAT EPIGENETIC MODIFICATIONS OF CCCDNA CONTRIBUTE TO VIRAL REPLICATION AND THE OUTCOME OF CHRONIC HBV INFECTION. HERE, WE SUMMARIZE CURRENT PROGRESS ON HBV EPIGENETICS RESEARCH AND THE THERAPEUTIC IMPLICATIONS FOR CHRONIC HBV INFECTION BY LEARNING FROM THE EPIGENETIC THERAPIES FOR CANCER AND OTHER VIRAL DISEASES, WHICH MAY OPEN A NEW VENUE TO CURE CHRONIC HEPATITIS B. (HEPATOLOGY 2017;66:2066-2077). 2017 19 5936 34 TARGETING HEPATITIS B VIRUS COVALENTLY CLOSED CIRCULAR DNA AND HEPATITIS B VIRUS X PROTEIN: RECENT ADVANCES AND NEW APPROACHES. CHRONIC HEPATITIS B VIRUS (HBV) INFECTION REMAINS A WORLDWIDE CONCERN AND PUBLIC HEALTH PROBLEM. TWO KEY ASPECTS OF THE HBV LIFE CYCLE ARE ESSENTIAL FOR VIRAL REPLICATION AND THUS THE DEVELOPMENT OF CHRONIC INFECTIONS: THE ESTABLISHMENT OF THE VIRAL MINICHROMOSOME, COVALENTLY CLOSED CIRCULAR (CCC) DNA, WITHIN THE NUCLEUS OF INFECTED HEPATOCYTES AND THE EXPRESSION OF THE REGULATORY HEPATITIS B VIRUS X PROTEIN (HBX). INTERESTINGLY, NUCLEAR HBX REDIRECTS HOST EPIGENETIC MACHINERY TO ACTIVATE CCCDNA TRANSCRIPTION. IN THIS PERSPECTIVE, WE PROVIDE AN OVERVIEW OF RECENT ADVANCES IN UNDERSTANDING THE REGULATION OF CCCDNA AND THE MECHANISTIC AND FUNCTIONAL ROLES OF HBX. WE ALSO DESCRIBE THE PROGRESS TOWARD TARGETING BOTH CCCDNA AND HBX FOR THERAPEUTIC PURPOSES. FINALLY, WE OUTLINE STANDING QUESTIONS IN THE FIELD AND PROPOSE COMPLEMENTARY CHEMICAL BIOLOGY APPROACHES TO ADDRESS THEM. 2019 20 1178 31 CONTROL OF CCCDNA FUNCTION IN HEPATITIS B VIRUS INFECTION. THE TEMPLATE OF HEPATITIS B VIRUS (HBV) TRANSCRIPTION, THE COVALENTLY CLOSED CIRCULAR DNA (CCCDNA), PLAYS A KEY ROLE IN THE LIFE CYCLE OF THE VIRUS AND PERMITS THE PERSISTENCE OF INFECTION. NOVEL MOLECULAR TECHNIQUES HAVE OPENED NEW POSSIBILITIES TO INVESTIGATE THE ORGANIZATION AND THE ACTIVITY OF THE CCCDNA MINICHROMOSOME IN VIVO, AND RECENT ADVANCES HAVE STARTED TO SHED LIGHT ON THE COMPLEXITY OF THE MECHANISMS CONTROLLING CCCDNA FUNCTION. NUCLEAR CCCDNA ACCUMULATES IN HEPATOCYTE NUCLEI AS A STABLE MINICHROMOSOME ORGANIZED BY HISTONE AND NON-HISTONE VIRAL AND CELLULAR PROTEINS. IDENTIFICATION OF THE MOLECULAR MECHANISMS REGULATING CCCDNA STABILITY AND ITS TRANSCRIPTIONAL ACTIVITY AT THE RNA, DNA AND EPIGENETIC LEVELS IN THE COURSE OF CHRONIC HEPATITIS B (CH-B) INFECTION MAY REVEAL NEW POTENTIAL THERAPEUTIC TARGETS FOR ANTI-HBV DRUGS AND HENCE ASSIST IN THE DESIGN OF STRATEGIES AIMED AT SILENCING AND EVENTUALLY DEPLETING THE CCCDNA RESERVOIR. 2009