Hepatitis B: two major breakthroughs raise hopes of eradicating chronic illness

Infection with hepatitis B virus (HBV) causes more than a million deaths each year, largely because of complications like cirrhosis and liver cancer. There is now an effective vaccine to prevent infection, but available treatments only control viral replication rather than curing the disease, and they often have to be taken for life.

Two recent breakthroughs in the Institut Pasteur's research offer real hopes of progress for patients living with chronic infection, whose immune system is unable to eliminate HBV.

The Institut Pasteur obtains a combination of human monoclonal antibodies to combat the virus more effectively

First, the team led by Hugo Mouquet, Head of the Institut Pasteur's Humoral Immunology Unit, explored the way in which some individuals are naturally able to eliminate the virus from their body. The scientists reproduced and studied the antibodies produced by memory B cells – the "sentinels" of the immune system – in people considered to be "cured."

"We identified various categories of specific antibodies capable of recognizing several regions of the hepatitis B virus surface protein, which are effective in neutralizing the virus," explains the scientist. By combining two antibody types (anti-preS2 and anti-S), the team obtained a potent antiviral effect. This was successfully tested in an animal model – the quantity of virus in the blood was significantly reduced and the effect has the potential to last over time.

This approach paves the way for a new type of immunotherapy "which involves administering antibodies with potent antiviral activity to chronically infected individuals, to help their immune system combat the virus," explains Hugo Mouquet.

The Institut Pasteur shows new drug to be effective in achieving a lasting cure

Another highly promising breakthrough is the research by Hélène Strick-Marchand, group leader in the Innate Immunity Unit (led by James di Santo), in testing an original new drug. The molecule, initially developed by the chemists Franck Amblard and Raymond Schinazi at Emory University, has been translated into a treatment known as ALG-000184 or Pevifoscorvir sodium, currently in Phase II clinical trials. The treatment targets the capsid, a protective shell around the virus, to make it incapable of replicating.

In a mouse model with a humanized immune system and liver, the Institut Pasteur confirmed that "the drug eliminates virtually all traces of the virus," explains the scientist. "But its mechanism of action goes further than that. Following treatment completion, half of the animals were able to control infection over the long term because their own immune response had been reactivated."

For the first time, a "functional cure" was obtained in this model – a result achieved in just 5 to 10% of cases using current treatments. This analytical research, conducted independently,¹ demonstrates that we can realistically hope for more than just enabling patients to control the virus. A future free of hepatitis B virus is within our grasp.

Basic research – a source of innovation to tackle infectious disease threats

These two discoveries reflect the Institut Pasteur's ambitions and its strategic approach in combining scientific excellence and innovation to tackle major infectious disease threats such as hepatitis B, which remains an urgent challenge. By improving our understanding of the immune system's natural weapons and developing more effective treatments, we can be confident that we might one day turn the page on this chronic disease.

Sources :

In vivo efficacy of combined human broadly neutralizing antibodies against hepatitis B virus, Cell Reports, 23 décembre 2025.

Maxime Beretta¹, Ariel Mechaly^2,8, Cyril Planchais^1,8, Ahmed Haouz², Célia Caillet-Saguy¹, Nathan Szerman⁴, Yada Aronthippaitoon⁴, Marie-Noëlle Ungeheuer⁵, Stanislas Pol⁶, Catherine Gaudy-Graffin⁷, Camille Sureau⁴, Maryline Bourgine^1,3,9, and Hugo Mouquet^1,9,10

¹Institut Pasteur, Université Paris Cité , Humoral Immunology Unit, 75015 Paris, France

²Institut Pasteur, Université Paris Cité , Crystallography Platform-C2RT, 75015 Paris, France

³Institut Pasteur, Université Paris Cité , Department of Virology, 75015 Paris, France

⁴INSERM U1259, Université de Tours, 37044 Tours, France

⁵Institut Pasteur, ICAReB-Biobank, Centre de Ressources Biologiques, 75015 Paris, France

⁶AP-HP Centre, Université Paris Centre, Groupe Hospitalier Cochin Port Royal, DMU Cancérologie et spécialités médico-chirurgicales, Service des Maladies du foie, Université Paris Cité , 75006 Paris, France

⁷Laboratoire de Bactériologie-Virologie-Hygiéne, CHRU de Tours, INSERM U1259, 37044 Tours, France

⁸These authors contributed equally

⁹Senior author

¹⁰Lead contact

Functional immune responses induced by a capsid assembly modulator in chronic hepatitis B virus-infected humanized mice, Cell Host & Microbe, 14 janvier 2026.

Priyanka Fernandes^1,8, Yidan Wang^1,8, Jean-Marc Doisne¹, Anna Thaller¹, Oriane Fiquet¹, Rémy Dailleux¹, Franck Amblard², Barbara Testoni³, Yada Aronthippaitoon⁴, Hugo Mouquet⁵, Camille Sureau⁴, Bastien Reyné⁶, Camilla Tiezzi¹, Patrick Soussan⁷, Massimo Levrero³, Fabien Zoulim³, Raymond F. Schinazi², and Helene Strick-Marchand^1,9

¹Institut Pasteur, Université Paris Cité, Inserm U1223, Innate Immunity Unit, 75015 Paris, France

²Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, and Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA

³Lyon Hepatology Institute, IHU EVEREST, UMR Inserm - Université Claude Bernard Lyon 1 U1350 PaThLiv, Hospices Civils de Lyon, Lyon, France

⁴INSERM U1259, Université de Tours, Tours, France

⁵Institut Pasteur, Université Paris Cité , Humoral Immunology Unit, 75015 Paris, France

⁶Université Bordeaux, INSERM, INRIA, BPH, U1219, 33000 Bordeaux, France

⁷Sorbonne Université , Centre de Recherche Saint-Antoine, INSERM U938, APHP, GHU Paris-Est, Paris, France

⁸These authors contributed equally

⁹Lead contact