Background and Aims Interferon (IFN)‐α, composed of numerous subtypes, plays a crucial role in immune defense. As the most studied subtype, IFN‐α2 has been used for treating chronic hepatitis B virus (HBV) infection, with advantages of finite treatment duration and sustained virologic response, but its efficacy remains relatively low. This study aimed to screen for IFN‐α subtypes with the highest anti‐HBV potency and to characterize mechanisms of IFN‐α–mediated HBV restriction. Approach and Results Using cell culture–based HBV infection systems and a human‐liver chimeric mouse model, IFN‐α subtype–mediated antiviral response and signaling activation were comprehensively analyzed. IFN‐α14 was identified as the most effective subtype in suppression of HBV covalently closed circular DNA transcription and HBV e antigen/HBV surface antigen production, with median inhibitory concentration values approximately 100‐fold lower than those of the conventional IFN‐α2. IFN‐α14 alone elicited IFN‐α and IFN‐γ signaling crosstalk in a manner similar to the combined use of IFN‐α2 and IFN‐γ, inducing multiple potent antiviral effectors, which synergistically restricted HBV replication. Guanylate binding protein 5, one of the most differentially expressed genes between IFN‐α14–treated and IFN‐α2–treated liver cells, was identified as an HBV restriction factor. A strong IFN‐α–IFN‐α receptor subunit 1 interaction determines the anti‐HBV activity of IFN‐α. The in vivo anti‐HBV activity of IFN‐α14 and treatment‐related transcriptional patterns were further confirmed, and few adverse effects were observed. Conclusions A concerted IFN‐α and IFN‐γ response in liver, which could be efficiently elicited by IFN‐α subtype 14, is associated with potent HBV suppression. These data deepen the understanding of the divergent activities of IFN‐α subtypes and the mechanism underlying the synergism between IFN‐α and IFN‐γ signaling, with implications for improved IFN therapy and HBV curative strategies.

Pandemic SARS-CoV-2 has caused unprecedented mortalities. Vaccine is in urgent need to stop the pandemic. Despite great progresses on SARS-CoV-2 vaccine development, the efficacy of the vaccines remains to be determined. Deciphering the interactions of the viral epitopes with the elicited neutralizing antibodies in convalescent population inspires the vaccine development. In this study, we devised a peptide array composed of 20-mer overlapped peptides of spike (S), membrane (M) and envelope (E) proteins, and performed a screening with 120 COVID-19 convalescent sera and 24 non-COVID-19 sera. We identified five SARS-CoV-2-specific dominant epitopes that reacted with above 40% COVID-19 convalescent sera. Of note, two peptides non-specifically interacted with most of the non-COVID-19 sera. Neutralization assay indicated that only five sera completely blocked viral infection at the dilution of 1:200. By using a peptide-compete neutralizing assay, we found that three dominant epitopes partially competed the neutralization activity of several convalescent sera, suggesting antibodies elicited by these epitopes played an important role in neutralizing viral infection. The epitopes we identified in this study may serve as vaccine candidates to elicit neutralizing antibodies in most vaccinated people or specific antigens for SARS-CoV-2 diagnosis.

Pandemic SARS-CoV-2 has infected over 10 million people and caused over 500,000 mortalities. Vaccine development is in urgent need to stop the pandemic. Despite great progresses on SARS-CoV-2 vaccine development, the efficacy of the vaccines remains to be determined. Deciphering the interactions of the viral epitopes with their elicited neutralizing antibodies in the convalescent COVID-19 population inspires the vaccine development. In this study, we devised a peptide array composed of 20-mer overlapped peptides of spike (S), membrane (M) and envelope (E) proteins, and performed a screening with 120 COVID-19 convalescent serums and 24 non-COVID-19 serums. We identified five SARS-CoV-2-specific dominant epitopes that reacted with above 40% COVID-19 convalescent serums. Epitopes in the receptor-binding domain (RBD) of S ill reacted with the convalescent serums. Of note, two peptides non-specifically interacted with most of the non-COVID-19 serums. Neutralization assay indicated that only five serums completely blocked viral infection at the dilution of 1:200. By using a peptide-compete neutralizing assay, we found that three dominant epitopes partially competed the neutralization activity of several convalescent serums, suggesting antibodies elicited by these epitopes played an important role in neutralizing viral infection. The epitopes we identified in this study may serve as vaccine candidates to elicit neutralizing antibodies in most vaccinated people or specific antigens for SARS-CoV-2 diagnosis.

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/CRISPRassociated 9 (Cas9)-mediated cccDNA targeting were compared between cccDNAs with distinct transcriptional activities. Interferonα treatment and hepatitis B x protein (HBx) deletion were applied as two strategies for cc-cDNA 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

Global temporal quantitative proteomic and transcriptomic analysis using long-term hepatitis B virus (HBV)-infected primary human hepatocytes uncovered extensive remodeling of the host proteome and transcriptome and revealed cytopathic effects of long-term viral replication. Metabolic-, complement-, cytoskeleton-, mitochondrial-, and oxidation-related pathways were modulated at transcriptional or posttranscriptional levels, which could be partially rescued by early, rather than late, NA therapy and could be relieved by blocking viral antigens with RNAi.