1 3861 101 ISOLATION OF HUMAN ANTIGEN-SPECIFIC REGULATORY T CELLS WITH HIGH SUPPRESSIVE FUNCTION. ADOPTIVE TRANSFER OF REGULATORY T (TREG) CELLS COULD BE AN ALTERNATIVE TO CHRONIC IMMUNOSUPPRESSION FOR PREVENTION OF ALLOGENEIC GRAFT REJECTION. WHILE POLYSPECIFIC TREG CELLS CAN PREVENT IMMUNE RESPONSES UNDER LYMPHOPENIC CONDITIONS, AG-SPECIFIC TREG CELLS ARE NEEDED TO TREAT AUTOIMMUNITY AND GRAFT REJECTION. YET, RELIABLE MARKERS FOR AG-SPECIFIC TREG CELLS ARE MISSING. WE REPORT THAT LATENCY-ASSOCIATED PEPTIDE (LAP) AND GLYCOPROTEIN A REPETITIONS PREDOMINANT (GARP) CAN IDENTIFY HUMAN AG-SPECIFIC TREG CELLS. IN ADDITION, WE SHOW THAT THE DEPLETION OF CD154(+) CELLS FROM LAP(+) OR GARP(+) TREG CELLS INCREASES THE TREG-CELL PURITY TO OVER 90%, AS ASSESSED BY EPIGENETIC ANALYSIS. THESE AG-SPECIFIC TREG CELLS CAN BE ISOLATED MAGNETICALLY AND MIGHT CONTRIBUTE TO THE DEVELOPMENT OF GMP-BASED PROTOCOLS. IN ADDITION, AG-SPECIFIC TREG CELLS ARE FUNCTIONALLY FAR SUPERIOR TO CD4(+) CD25(HIGH) OR CD4(+) CD25(HIGH) CD127(LOW) TREG CELLS IN VITRO AND IN PREVENTING STRONG ALLOREACTIONS IN HUMANIZED MICE. THEY COULD, THEREFORE, HAVE A HIGH THERAPEUTIC POTENTIAL FOR THE CONTROL OF ALLOIMMUNE, AUTOIMMUNE, AND ALLERGIC IMMUNE RESPONSES IN PATIENTS. 2014 2 3529 28 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 3 1904 29 ENHANCED RETINAL GANGLION CELL SURVIVAL IN GLAUCOMA BY HYPOXIC POSTCONDITIONING AFTER DISEASE ONSET. THE NEUROPROTECTIVE EFFICACY OF ADAPTIVE EPIGENETICS, WHEREIN BENEFICIAL GENE EXPRESSION CHANGES ARE INDUCED BY NONHARMFUL "CONDITIONING" STIMULI, IS NOW WELL ESTABLISHED IN SEVERAL ACUTE, PRECLINICAL CENTRAL NERVOUS SYSTEM INJURY MODELS. RECENTLY, IN A MOUSE MODEL OF GLAUCOMA, WE DEMONSTRATED RETINAL GANGLION CELL (RGC) PROTECTION BY REPETITIVELY "PRECONDITIONING" WITH HYPOXIA PRIOR TO DISEASE ONSET, INDICATING AN EPIGENETIC APPROACH MAY ALSO YIELD BENEFITS IN CHRONIC NEURODEGENERATIVE DISEASE. HEREIN, WE DETERMINED WHETHER PRESENTING THE REPETITIVE HYPOXIC STIMULUS AFTER DISEASE INITIATION [REPETITIVE HYPOXIC "POSTCONDITIONING" (RH-POST)] COULD AFFORD SIMILAR FUNCTIONAL AND MORPHOLOGIC PROTECTION AGAINST GLAUCOMATOUS RGC INJURY. CHRONIC ELEVATIONS IN INTRAOCULAR PRESSURE (IOP) WERE INDUCED UNILATERALLY IN ADULT MALE C57BL/6 MICE BY EPISCLERAL VEIN LIGATION. MICE WERE RANDOMIZED TO AN RH-POST [1 H OF SYSTEMIC HYPOXIA (11% OXYGEN) EVERY OTHER DAY, STARTING 4 DAYS AFTER IOP ELEVATION] OR AN UNTREATED CONTROL GROUP. AFTER 3 WEEKS OF EXPERIMENTAL GLAUCOMA, THE 21-27% REDUCTION AND 5-25% PROLONGATION IN FLASH VISUAL-EVOKED POTENTIAL AMPLITUDES AND LATENCIES, RESPECTIVELY, AND THE 30% IMPAIRMENT IN VISUAL ACUITY WERE ROBUSTLY IMPROVED IN RH-POST-TREATED MICE, AS WAS THE 17% LOSS IN RGC SOMA NUMBER AND 20% REDUCTION IN AXON INTEGRITY. THESE PROTECTIVE EFFECTS WERE OBSERVED WITHOUT RH-POST AFFECTING IOP. THE PRESENT FINDINGS DEMONSTRATE THAT FUNCTIONAL AND MORPHOLOGIC PROTECTION OF RGCS CAN BE REALIZED BY STIMULATING EPIGENETIC RESPONSES DURING THE EARLY STAGES OF DISEASE, AND THUS CONSTITUTE A NEW CONCEPTUAL APPROACH TO GLAUCOMA THERAPEUTICS. 2015 4 3938 26 LNC(ING)RNAS TO THE "SHOCK AND KILL" STRATEGY FOR HIV-1 CURE. THE ADVENT OF ANTIRETROVIRAL THERAPY ALMOST 25 YEARS AGO HAS TRANSFORMED HIV-1 INFECTION INTO A MANAGEABLE CHRONIC CONDITION, ALBEIT STILL INCURABLE. THE INABILITY OF THE TREATMENT REGIMEN TO ELIMINATE LATENTLY INFECTED CELLS THAT HARBOR THE VIRUS IN AN EPIGENETICALLY SILENT STATE POSES A MAJOR HURDLE. CURRENT CURE APPROACHES ARE FOCUSED ON A "SHOCK AND KILL" STRATEGY THAT USES LATENCY-REVERSING AGENTS TO CHEMICALLY REVERSE THE PROVIRAL QUIESCENCE IN LATENTLY INFECTED CELLS, FOLLOWED BY IMMUNE-MEDIATED CLEARANCE OF REACTIVATED CELLS. TO DATE, HUNDREDS OF COMPOUNDS HAVE BEEN INVESTIGATED FOR VIRAL REACTIVATION, YET NONE HAS RESULTED IN A FUNCTIONAL CURE. THE INSUFFICIENCY OF THESE LATENCY-REVERSING AGENTS (LRAS) ALONE INDICATES A CRITICAL NEED FOR ADDITIONAL, ALTERNATE APPROACHES SUCH AS GENETIC MANIPULATION. LONG NON-CODING RNAS (LNCRNAS) ARE AN EMERGING CLASS OF REGULATORY RNAS WITH FUNCTIONAL ROLES IN MANY CELLULAR PROCESSES, INCLUDING EPIGENETIC MODULATION. A NUMBER OF LNCRNAS HAVE ALREADY BEEN IMPLICATED TO PLAY IMPORTANT ROLES IN HIV-1 LATENCY AND, AS SUCH, PHARMACOLOGICAL MODULATION OF LNCRNAS CONSTITUTES A RATIONAL ALTERNATIVE APPROACH IN HIV-1 CURE RESEARCH. IN THIS REVIEW, WE DISCUSS THE CURRENT STATE OF KNOWLEDGE OF THE ROLE OF LNCRNAS IN HIV-1 INFECTION AND EXPLORE THE SCOPE FOR A LNCRNA-MEDIATED GENETIC APPROACH WITHIN THE SHOCK AND KILL STRATEGY OF HIV-1 CURE. 2021 5 3794 32 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 6 5368 17 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 7 5689 26 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 8 3186 21 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 9 4816 24 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 10 3188 26 HBV-SPECIFIC CD8+ T-CELL TOLERANCE IN THE LIVER. HEPATITIS B VIRUS (HBV) REMAINS A LEADING CAUSE OF LIVER-RELATED MORBIDITY AND MORTALITY THROUGH CHRONIC HEPATITIS THAT MAY PROGRESS TO LIVER CIRRHOSIS AND CANCER. THE CENTRAL ROLE PLAYED BY HBV-SPECIFIC CD8+ T CELLS IN THE CLEARANCE OF ACUTE HBV INFECTION, AND HBV-RELATED LIVER INJURY IS NOW WELL ESTABLISHED. VIGOROUS, MULTIFUNCTIONAL CD8+ T CELL RESPONSES ARE USUALLY INDUCED IN MOST ADULT-ONSET HBV INFECTIONS, WHILE CHRONIC HEPATITIS B (CHB) IS CHARACTERIZED BY QUANTITATIVELY AND QUALITATIVELY WEAK HBV-SPECIFIC CD8+ T CELL RESPONSES. THE MOLECULAR BASIS OF THIS DICHOTOMY IS POORLY UNDERSTOOD. GENOMIC ANALYSIS OF DYSFUNCTIONAL HBV-SPECIFIC CD8+ T CELLS IN CHB PATIENTS AND VARIOUS MOUSE MODELS SUGGEST THAT MULTIFACETED MECHANISMS INCLUDING NEGATIVE SIGNALING AND METABOLIC ABNORMALITIES COOPERATIVELY ESTABLISH CD8+ T CELL DYSFUNCTION. IMMUNOREGULATORY CELL POPULATIONS IN THE LIVER, INCLUDING LIVER RESIDENT DENDRITIC CELLS (DCS), HEPATIC STELLATE CELLS (HSCS), MYELOID-DERIVED SUPPRESSOR CELLS (MDSCS), MAY CONTRIBUTE TO INTRAHEPATIC CD8+ T CELL DYSFUNCTION THROUGH THE PRODUCTION OF SOLUBLE MEDIATORS, SUCH AS ARGINASE, INDOLEAMINE 2,3-DIOXYGENASE (IDO) AND SUPPRESSIVE CYTOKINES AND THE EXPRESSION OF CO-INHIBITORY MOLECULES. A SERIES OF RECENT STUDIES WITH MOUSE MODELS OF HBV INFECTION SUGGEST THAT GENETIC AND EPIGENETIC CHANGES IN DYSFUNCTIONAL CD8+ T CELLS ARE THE MANIFESTATION OF PROLONGED ANTIGENIC STIMULATION, AS WELL AS THE ABSENCE OF CO-STIMULATORY OR CYTOKINE SIGNALING. THESE NEW FINDINGS MAY PROVIDE POTENTIAL NEW TARGETS FOR IMMUNOTHERAPY AIMING AT INVIGORATING HBV-SPECIFIC CD8+ T CELLS, WHICH HOPEFULLY CURES CHB. 2021 11 5365 18 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 12 5936 16 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 13 4055 27 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 14 3782 21 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 15 6479 30 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 16 1178 18 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 17 442 17 ANTIVIRAL THERAPIES FOR HEPATITIS B VIRUS-RELATED HEPATOCELLULAR CARCINOMA. CHRONIC HEPATITIS B VIRUS (HBV) INFECTION IS A CRITICAL RISK FACTOR FOR THE CARCINOGENESIS AND PROGRESSION OF HEPATOCELLULAR CARCINOMA (HCC). IT PROMOTES HCC DEVELOPMENT BY INDUCING LIVER FIBROGENESIS, GENETIC AND EPIGENETIC ALTERATIONS, AND THE EXPRESSION OF ACTIVE VIRAL-CODED PROTEINS. EFFECTIVE ANTIVIRAL TREATMENTS INHIBIT THE REPLICATION OF HBV, REDUCE SERUM VIRAL LOAD AND ACCELERATE HEPATITIS B E ANTIGEN SERUM CONVERSION. TIMELY INITIATION OF ANTIVIRAL TREATMENT IS NOT ONLY ESSENTIAL FOR PREVENTING THE INCIDENCE OF HCC IN CHRONIC HEPATITIS B PATIENTS, BUT ALSO IMPORTANT FOR REDUCING HBV REACTIVATION, IMPROVING LIVER FUNCTION, REDUCING OR DELAYING HCC RECURRENCE, AND PROLONGING OVERALL SURVIVAL OF HBV-RELATED HCC PATIENTS AFTER CURATIVE AND PALLIATIVE THERAPIES. THE SELECTION OF ANTIVIRAL DRUGS, MONITORING OF INDICATORS SUCH AS HBV DNA AND HEPATITIS B SURFACE ANTIGEN, AND TIMELY RESCUE TREATMENT WHEN NECESSARY, ARE ESSENTIAL IN ANTIVIRAL THERAPIES FOR HBV-RELATED HCC. 2015 18 3380 24 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 19 3185 19 HBC BINDS TO THE CPG ISLANDS OF HBV CCCDNA AND PROMOTES AN EPIGENETIC PERMISSIVE STATE. HBV COVALENTLY CLOSED CIRCULAR DNA (CCCDNA) IS THE TEMPLATE FOR THE TRANSCRIPTION OF HBV. HBV CORE PROTEIN (HBC) IS A MAIN COMPONENT OF THE HBV CCCDNA MINICHROMOSOME. HOWEVER, THE FUNCTION OF HBC IN CCCDNA IS NOT FULLY UNDERSTOOD. IN LIGHT OF RECENT FINDINGS THAT HBV CCCDNA MAY BE REGULATED EPIGENETICALLY, WE ANALYZED THE BINDING OF HBC TO CCCDNA AND THE IMPACT OF HBC ON CCCDNA EPIGENETIC PROFILE IN THE LIVER BIOPSY SAMPLES OF 22 PATIENTS WITH CHRONIC HEPATITIS B (CHB). WE FOUND THAT HBC BINDING TO HBV CCCDNA OCCURRED PREFERENTIALLY AT CPG ISLAND 2, AN IMPORTANT REGION FOR THE REGULATION OF HBV TRANSCRIPTION. FURTHERMORE, THE RELATIVE ABUNDANCES OF HBC BINDING TO CPG ISLAND 2 WERE POSITIVELY CORRELATED WITH THE RATIOS OF RELAXED CIRCULAR DNA TO CCCDNA AND THE LEVELS OF SERUM HBV DNA IN THOSE PATIENTS. INTERESTINGLY, THE RELATIVE ABUNDANCES OF HBC BINDING TO CPG ISLAND 2 WERE ASSOCIATED WITH THE BINDING OF CREB BINDING PROTEIN (CBP) AND WITH HYPOMETHYLATION IN CPG ISLAND 2 OF HBV CCCDNA MINICHROMOSOMES. HOWEVER, RELATIVELY HIGHER AMOUNTS OF HBC BINDING TO CPG ISLAND 2 OF CCCDNA WERE ACCOMPANIED BY LOWER AMOUNTS OF HDAC1 BINDING. MULTIVARIATE ANALYSIS REVEALED THAT THE ABUNDANCES OF HBC BINDING TO CPG ISLAND 2 OF CCCDNA AND POSITIVE HBEAG WERE INDEPENDENT FACTORS ASSOCIATED WITH THE REPLICATION OF HBV (P = 0.001 FOR BOTH). APPARENTLY, HBC IS A POSITIVE REGULATOR OF HBV TRANSCRIPTION AND REPLICATION, MAINTAINING THE PERMISSIVE EPIGENETIC STATE IN THE CRITICAL REGION OF THE HBV CCCDNA MINICHROMOSOMES. 2011 20 6697 22 VARICELLA-ZOSTER VIRUS HUMAN GANGLIONIC LATENCY: A CURRENT SUMMARY. VARICELLA-ZOSTER VIRUS (VZV) IS A UBIQUITOUS HUMAN HERPES VIRUS TYPICALLY ACQUIRED IN CHILDHOOD WHEN IT CAUSES VARICELLA (CHICKENPOX), FOLLOWING WHICH THE VIRUS ESTABLISHES A LATENT INFECTION IN TRIGEMINAL AND DORSAL ROOT GANGLIA THAT LASTS FOR THE LIFE OF THE INDIVIDUAL. VZV SUBSEQUENTLY REACTIVATES, SPONTANEOUSLY OR AFTER SPECIFIC TRIGGERING FACTORS, TO CAUSE HERPES ZOSTER (SHINGLES), WHICH MAY BE COMPLICATED BY POSTHERPETIC NEURALGIA AND SEVERAL OTHER NEUROLOGICAL COMPLICATIONS INCLUDING VASCULOPATHY. OUR UNDERSTANDING OF VZV LATENCY LAGS BEHIND OUR KNOWLEDGE OF HERPES SIMPLEX VIRUS TYPE 1 (HSV-1) LATENCY PRIMARILY DUE TO THE DIFFICULTY IN PROPAGATING THE VIRUS TO HIGH TITERS IN A CELL-FREE STATE, AND THE LACK OF A SUITABLE SMALL-ANIMAL MODEL FOR STUDYING VIRUS LATENCY AND REACTIVATION. IT IS NOW ESTABLISHED BEYOND DOUBT THAT LATENT VZV IS PREDOMINANTLY LOCATED IN HUMAN GANGLIONIC NEURONS. VIRUS GENE TRANSCRIPTION DURING LATENCY IS EPIGENETICALLY REGULATED, AND APPEARS TO BE RESTRICTED TO EXPRESSION OF AT LEAST SIX GENES, WITH EXPRESSION OF GENE 63 BEING THE HALLMARK OF LATENCY. HOWEVER, VIRAL GENE TRANSCRIPTION MAY BE MORE EXTENSIVE THAN PREVIOUSLY THOUGHT. THERE IS ALSO EVIDENCE FOR SEVERAL VZV GENES BEING EXPRESSED AT THE PROTEIN LEVEL, INCLUDING VZV GENE 63-ENCODED PROTEIN, BUT RECENT EVIDENCE SUGGESTS THAT THIS MAY NOT BE A COMMON EVENT. THE NATURE AND EXTENT OF THE CHRONIC INFLAMMATORY RESPONSE IN LATENTLY INFECTED GANGLIA IS ALSO OF CURRENT INTEREST. THERE REMAIN SEVERAL QUESTIONS CONCERNING THE VZV LATENCY PROCESS THAT STILL NEED TO BE RESOLVED UNAMBIGUOUSLY AND IT IS LIKELY THAT THIS WILL REQUIRE THE USE OF NEWLY DEVELOPED MOLECULAR TECHNOLOGIES, SUCH AS GEXPS MULTIPLEX POLYMERASE CHAIN REACTION (PCR) FOR VIRUS TRANSCRIPTIONAL ANALYSIS AND CHIP-SEQ TO STUDY THE EPIGENETIC OF LATENT VIRUS GENOME ( LIU ET AL, 2010 , BMC BIOL 8: 56). 2010