BACKGROUND:Chronic hepatitis B virus (HBV) infection is characterised by immune dysfunction. While conventional T cell responses have been extensively studied, the role of γδ T cells, innate-like cytotoxic lymphocytes enriched in the liver, remains incompletely understood. OBJECTIVE:To characterise γδ T cell subsets in HBV infection and assess their association with viral control and antibody-dependent cellular cytotoxicity (ADCC). DESIGN:Peripheral blood from patients with chronic (n=83) and acute (n=16) HBV infection, healthy controls (n=31), and cord-blood donors (n=3) was analysed using multiparameter flow cytometry, single-cell RNA sequencing and in vitro ADCC assays. RESULTS:A distinct CD16+ γδ T cell subset inversely correlated with hepatitis B core-related antigen (HBcrAg), a surrogate of intrahepatic viral replication. CD16+ γδ T cells displayed a cytotoxic signature, whereas CD16⁻ cells showed inflammatory, non-cytotoxic profiles. On hepatitis B surface antigen-specific antibody stimulation, CD16+ γδ T cells mounted potent ADCC responses, mainly mediated by Vδ2+ cells expressing the activating receptor CD226, while Vδ1+ cells preferentially expressed the inhibitory receptor TIGIT. Cytotoxic CD16+ Vδ2+ γδ T cells were present in both blood and liver. CD16+ γδ T cells were expanded and highly functional in acute HBV but reduced and partially impaired in chronic infection. Neonatal cord-blood-derived γδ T cells lacked CD16 expression and displayed limited ADCC potential. CONCLUSIONS:CD16+ γδ T cells mediate antibody-dependent antiviral immunity in HBV infection. Their inverse association with HBcrAg links γδ T cell-mediated ADCC to viral control and highlights this pathway as a target for HBV cure strategies.

The mechanisms driving immune dysregulation in long COVID disease remain elusive. Here we integrated single-cell multiome data, immunological profiling and functional assays to investigate immune alterations across multiple cohorts. A transcriptional state in circulating monocytes (LC-Mo) was enriched in individuals with mild–moderate acute infection and accompanied by persistent elevations of plasma CCL2, CXCL11 and TNF. LC-Mo showed TGFβ and WNT–β-catenin signaling and correlated with fatigue severity. Protein markers of LC-Mo were increased in individuals with pronounced fatigue or dyspnea, and those with severe respiratory symptoms showed higher LC-Mo expression. Epigenetically, LC-Mo exhibited AP-1- and NF-κB1-driven profibrotic programs. LC-Mo-like macrophages in bronchoalveolar lavage samples from individuals with severe respiratory symptoms displayed a profibrotic profile, and individuals with a high LC-Mo transcriptional state showed impaired interferon responses after stimulation. Collectively, our findings define a pathogenic monocyte transcriptional state linking systemic immune dysfunction to persistent long COVID disease, providing mechanistic insights and potential therapeutic targets. Li and colleagues describe a monocyte-specific transcriptional state along with a persistent elevation of inflammatory markers specifically found in individuals with long COVID who had mild-to-moderate disease during acute SARS-CoV-2 infection.

BACKGROUND:Previous exposure to hepatitis B virus (HBV) may influence the risk of developing hepatocellular carcinoma (HCC) and other liver-related events (LRE), in particular in patients after HCV cure. Previous studies were not conclusive and there are only few large studies on this topic from Europe. METHODS:We analysed clinical endpoints (≥ 3-point increase in MELD score, oesophageal variceal bleeding, ascites, encephalopathy, liver transplantation, death, with/without HCC; HCC alone) in patients cured from HCV. Data were obtained from the German Hepatitis C Registry. Patients after organ transplantation, a history of HCC, HIV co-infection, or HBsAg positivity were excluded. A subanalysis was conducted in patients with cirrhosis. Statistical analyses included logistic regression to identify predictors of clinical endpoints and Kaplan-Meier curves to analyse the influence of HBV serological markers. RESULTS:A cohort of 6198 patients fulfilled inclusion criteria, the median time of follow-up was 2.5 years (range 0.04-8.01). Serological evidence of previous HBV exposure was present in 1889 patients (anti-HBc positive). In patients with cirrhosis, univariate analyses identified anti-HBc positivity (odds ratio [OR], 1.48), cirrhosis (OR, 4.89), features of portal hypertension (ascites (OR, 5.66), oesophageal varices (OR, 4.88)), diabetes (OR, 3.23), and malignancies (OR, 10.34) as risk factors for composite LRE. In multivariable analysis, anti-HBc positivity (OR, 1.53) and cirrhosis (OR, 4.63) remained independent risk factors for the composite endpoints, whereas anti-HBc positivity was not associated with HCC or Kaplan-Meier survival analyses. CONCLUSIONS:Resolved HBV infection was not associated with the development of HCC or survival in Caucasians after HCV cure. Although anti-HBc positivity was linked to composite outcomes, its clinical relevance appears limited. TRIAL REGISTRATION:The registry was registered at the German Clinical Trials Register (DRKS; IDDRKS00009717).

Bulevirtide (BLV) is approved in Europe, Australia, and Russia for treatment of chronic hepatitis delta. Results from the MYR301 (NCT03852719) Phase 3 study showed monotherapy with BLV 2 mg/day (d) or 10 mg/d to be efficacious and safe through 144 weeks (W) of treatment. Here we analyse hepatitis delta virus (HDV) viral dynamics in patients (pts) achieving undetectable HDV RNA after varying durations of therapy.Data were analysed from 149 pts in MYR301 who were randomised to immediate treatment with BLV 2 or 10 mg/d for 144W or to 48W of no treatment followed by BLV 10 mg/d for 96W. Pts were followed for 96W after treatment; those achieving undetectable HDV RNA on therapy were stratified by time to first undetectability. HDV RNA viral dynamics and alanine aminotransferase (ALT) normalisation were analysed by stratum. Low-level viraemia was defined as HDV RNA below the lower limit of quantitation (<LLOQ), target detected.Baseline (BL) characteristics were similar across arms. Across all arms, 81/149 (54%) pts achieved undetectable HDV RNA during therapy, of whom 13/81 (16%) achieved this endpoint by W24, 22/81 (27%) between W24 and W48, 14/81 (17%) between W48 and W72, 16/81 (20%) between W72 and W96, and 16/81 (20%) after W96. Pts with lower BL HDV RNA levels had shorter time to first onset of undetectable HDV RNA. Pts achieving earlier undetectability were more likely to have undetectable HDV RNA at the end of treatment (EOT): 12/13 (92%) of those achieving undetectability by W24 had undetectable HDV RNA at EOT vs 18/22 (82%) of those doing so during W24–48, 12/14 (86%) of those doing so during W48–72, 12/16 (75%) of those doing so during W72–96, and 11/16 (69%) of those doing so after W96. Among all pts achieving undetectability, only 3 pts were later found to have on-treatment HDV RNA levels ≥LLOQ, though transient or persistent low-level viraemia was observed in 31/81 (38%) pts. There were no clear trends in ALT normalisation rates at EOT by time to undetectable HDV RNA (Figure). In the posttreatment period, earlier time to undetectable HDV RNA was associated with high rates of sustained undetectability (no posttreatment positive HDV RNA values). Among pts with undetectable HDV RNA at EOT and available follow-up data, 9/11 pts who achieved undetectable RNA during W0–24 had sustained undetectability vs 10/18, 2/12, 0/12, and 2/11 pts who achieved undetectable HDV RNA during W24–48, W48–72, and W72–96 and after W96. Among pts in the MYR301 trial who achieved undetectable HDV RNA with BLV monotherapy for 2–3 years, shorter time to onset of undetectable HDV RNA was associated with lower BL HDV RNA, a higher rate of undetectable HDV RNA at EOT, and fewer posttreatment relapses. On-treatment viral rebound after achieving undetectability was rare; however, low-level viraemia occurred in some pts. Further research is needed to know if pts with longer time to undetectability would achieve similar results with longer duration of therapy.

BACKGROUND & AIMS:Bulevirtide is approved in several countries and regions for the treatment of compensated chronic hepatitis D (CHD). However, long-term outcomes after treatment discontinuation remain unknown. METHODS:Patients with CHD (n = 150) were randomized to immediate treatment with bulevirtide 2 mg/day (n = 49) or 10 mg/day (n = 50) for 144 weeks (W), or a 48W delay before starting treatment (DT; n = 51) followed by bulevirtide 10 mg/day for 96W (DT/10 mg; n = 50), and 96W of post-treatment follow-up (FU96) in the MYR301 study. Efficacy endpoints included virologic response (VR; undetectable HDV RNA or ≥2 log10 IU/ml decline from baseline), combined response (CR; VR and alanine aminotransferase [ALT] normalization), ALT normalization, and undetectable HDV RNA. RESULTS:At the end of treatment (EOT), response rates in the 2, 10, and DT/10 mg groups were: VR, 73%, 76%, and 92%; ALT normalization, 59%, 60%, and 58%; CR, 57%, 54%, and 56%; and HDV RNA undetectability, 29%, 50%, and 52%. At FU96, VR rates declined to 33%, 30%, and 32%, respectively; CR rates were 24% across all groups. HDV RNA undetectability rates were 20%, 22%, and 20% at FU96. Sustained undetectability through follow-up was observed in 23/64 (36%) patients with undetectable HDV RNA at EOT, with weeks continuously undetectable at EOT being the most important predictor of sustained undetectability. Post-treatment hepatic serious adverse events occurred in 20/142 (14%) patients and resolved in 17/20 (85%). CONCLUSIONS:Bulevirtide treatment for CHD for up to 144W was safe and effective. Response rates decreased after treatment discontinuation; however, some patients had sustained undetectable HDV RNA throughout 2 years of follow-up. IMPACT AND IMPLICATIONS:Although bulevirtide is approved for treatment of chronic hepatitis D (CHD) in several countries and regions including the United States, the European Economic Area, the United Kingdom, Switzerland, the Russian Federation, Australia, and Canada, treatment outcomes beyond 2 years and after bulevirtide discontinuation remain unknown. In this analysis, we demonstrate that efficacy was maintained with bulevirtide monotherapy for up to 144 weeks compared with that at 96 weeks, while rates of HDV RNA undetectability continued to improve with extended treatment duration. Virologic and biochemical responses decreased after treatment discontinuation, but some patients with undetectable HDV at the end of treatment maintained HDV RNA undetectability post-treatment, with duration of continuous HDV RNA undetectability at the end of treatment being the strongest predictor of non-relapse. While most patients benefit from continued bulevirtide therapy, a subset of those who achieve undetectable HDV RNA may be able to discontinue treatment without loss of response even in the absence of HBsAg loss. CLINICAL TRIAL NUMBER:NCT03852719.

BACKGROUND AND AIMS:Hepatitis E virus (HEV) infection is very frequent in Europe with more than 2 million annual infections. Patients with liver cirrhosis may face an increased risk of suffering from acute-on-chronic liver failure (ACLF) due to HEV infection. We explored the consequences and prevalence of HEV infection in individuals with liver cirrhosis. METHODS:We retrospectively analysed the clinical outcome of all consecutive patients who were hospitalized at our center due to acute HEV infection and analysed their outcome between 2014 and 2024. Next, we tested 249 sera from 184 cirrhotic patients during individual episodes of acute hepatic decompensation for anti-HEV IgM and HEV-RNA to analyse the relevance of acute HEV infection as a triggering event. Finally, we established a single center cohort of patients with advanced liver cirrhosis, and assessed the anti-HEV IgG seroprevalence (n = 332). RESULTS:Over the past decade, 32 patients with liver cirrhosis who were hospitalized due to acute HEV infection were identified. Among these patients, 16 (50%) developed ACLF, resulting in five fatalities (31.3%) and three individuals (18.8%) requiring liver transplantation for survival. Of 249 sera obtained during acute hepatic decompensation, 11 (4.4%) were either HEV-RNA positive (n = 2) and/or anti-HEV IgM positive (n = 10), linking HEV infection to these acute decompensations. Screening of patients with liver cirrhosis for anti-HEV IgG showed that 67.2% of patients (223/332) were anti-HEV negative and thus at potential risk for future HEV infection. CONCLUSIONS:Patients with advanced liver cirrhosis are at risk of acute HEV infection, which is a relevant cause of hepatic decompensation and ACLF with high mortality in these patients. TRIAL REGISTRATION:DRKS00010664; NCT04801290.

Acute infection with hepatitis C virus (HCV) is a rare event that can be treated successfully with direct-acting antivirals (DAAs). As natural killer (NK) cells play an important role during the natural course of acute HCV, we assessed the NK cell compartment via flow cytometry and single-cell sequencing in longitudinally sampled patients with acute HCV and compared this to healthy controls and patients with chronic HCV. At the transcriptomic level, we identified a subset of highly activated NK cells with a robust type I interferon imprint. While the population of activated NK cells vanished after DAA-mediated cure, a long-term phenotypic imprint of infection was observed in comparison to healthy controls. Collectively, these data suggest an interferon-driven rise of an activated NK cell population during acute hepatitis C that is largely restored upon viral clearance. This study provides insights into the immunological basis for successful antiviral response to hepatitis C.