Selective depletion of HBV-infected hepatocytes by class A capsid assembly modulators requires high levels of intrahepatic HBV core protein

• DOI: 10.1128/aac.00420-24
• Publication Date: 2024-05-23T13:00:38Z
• Authors: Dmytro Kornyeyev; Zhijuan Song; Stacey Eng; Cameron Soulette; Ricardo Ramirez; Jennifer Tang; Qin Yue; Raju Subramanian; Shiva Zaboli; Christina Moon; Jane Tam; Jens Brodbeck; Abhishek Aggarwal; Lauri Diehl; Simon P. Fletcher; Anastasia Hyrina; Meghan M. Holdorf; Dara Burdette
• Keywords: Hepatitis B virus; 0303 health sciences; Hepatitis B Surface Antigens; Viral Core Proteins; Virus Assembly; Apoptosis; Virus Replication; Antiviral Agents; Hepatitis B Core Antigens; Mice; 03 medical and health sciences; Hepatitis B, Chronic; Capsid; Liver; Hepatocytes; Humans; Animals

ABSTRACT

Capsid assembly mediated by hepatitis B virus (HBV) core protein (HBc) is an essential part of the HBV replication cycle, which is the target for different classes of capsid assembly modulators (CAMs). While both CAM-A (“aberrant”) and CAM-E (“empty”) disrupt nucleocapsid assembly and reduce extracellular HBV DNA, CAM-As can also reduce extracellular HBV surface antigen (HBsAg) by triggering apoptosis of HBV-infected cells in preclinical mouse models. However, there have not been substantial HBsAg declines in chronic hepatitis B (CHB) patients treated with CAM-As to date. To investigate this disconnect, we characterized the antiviral activity of tool CAM compounds in HBV-infected primary human hepatocytes (PHHs), as well as in HBV-infected human liver chimeric mice and mice transduced with adeno-associated virus-HBV. Mechanistic studies in HBV-infected PHH revealed that CAM-A, but not CAM-E, induced a dose-dependent aggregation of HBc in the nucleus which is negatively regulated by the ubiquitin-binding protein p62. We confirmed that CAM-A, but not CAM-E, induced HBc-positive cell death in both mouse models via induction of apoptotic and inflammatory pathways and demonstrated that the degree of HBV-positive cell loss was positively correlated with intrahepatic HBc levels. Importantly, we determined that there is a significantly lower level of HBc per hepatocyte in CHB patient liver biopsies than in either of the HBV mouse models. Taken together, these data confirm that CAM-As have a unique secondary mechanism with the potential to kill HBc-positive hepatocytes. However, this secondary mechanism appears to require higher intrahepatic HBc levels than is typically observed in CHB patients, thereby limiting the therapeutic potential.