Several viruses strategically hijack host cellular machinery to create a replication-favorable environment by altering host cell components such as membrane composition, receptor availability, metabolism, protein synthesis, cytoskeletal organization, and cell cycle regulation [
1-
3]. Among these, metabolic regulation plays a pivotal role in shaping virus-host interactions, influencing pathogenesis, and exacerbating disease severity. For example, viral infections such as influenza, severe acute respiratory syndrome coronavirus 2, and respiratory syncytial virus disproportionately affect individuals with metabolic disorders, including obesity and diabetes [
4]. Similarly, hepatitis B virus (HBV), a hepatotropic virus, profoundly modulates hepatic metabolism, promoting viral persistence and disease progression [
5].
Given the liver’s central role in metabolism, HBV possesses unique characteristics as a metabolic virus [
6]. This distinct property allows HBV to reprogram host metabolic pathways to support this viral replication while simultaneously contributing to hepatic dysfunction. HBV infection has been linked to metabolic disorders such as fatty liver disease and diabetes, resulting not only from virus-induced inflammation and hepatocellular injury but also from the direct metabolic reprogramming of the liver by HBV [
7]. Consequently, this metabolic rewiring contributes to hepatocellular carcinoma (HCC) development and disrupts hepatic gene regulation, leading to broader metabolic impairments [
8].
Recent studies have revealed that metabolic regulation not only influences the severity of hepatitis but also creates a favorable environment for HBV replication. HBV activates glycolysis in hepatocytes and enhances lactate production through lactate dehydrogenase-A, thereby suppressing retinoic acid-inducible gene I-induced interferon production and facilitating immune evasion [
9]. Additionally, vitamin D, which is known to be involved in the regulation of immune responses, has also been well established as an inhibitor of HBV. Notably, hepatocytes infected with HBV exhibit a reduced expression of the vitamin D receptor [
10,
11].
Therefore, metabolic regulation is key focal points in HBV research, and numerous host factors related to these processes have continued to be identified in recent studies (
Table 1). It is plausible that the metabolic reprogramming influences HBV life cycle regulation; however, the underlying mechanisms remain elusive.
The HBV large S antigen directly interacts with pyruvate kinase isoform M2, a key regulator of glycolysis, thereby suppressing its enzymatic activity. This interaction increases glucose consumption while reducing lactate production, ultimately creating an oncogenic and immunosuppressive microenvironment [
12]. A study using HBV transgenic mice demonstrated that HBV alters lipid metabolism by hijacking binding immunoglobulin protein (Bip), leading to lipid accumulation in hepatocytes. The HBV small S antigen interacts with Bip, a key regulator of cellular homeostasis against unfolded protein response signaling, thereby alleviating post endoplasmic reticulum signaling inhibition and disrupting lipid metabolism [
13]. A multi-omics analysis of patients with HBV-associated HCC has revealed HBV-induced metabolic alterations in metabolites linked to primary bile acids and sphingolipids. These metabolites activate the MAPK/mTOR pathway, leading to metabolic reprogramming and establishing a self-sustaining feedback loop that may contribute to HCC progression [
6]. Furthermore, serum sphingosine-1-phosphate concentration has been identified as a host metabolite correlated with HBV DNA levels in chronic hepatitis B patients. Sphingosine kinase 1 expression was upregulated in the liver tissues of HBV-positive HCC patients, and this upregulation was driven by HBV-induced transcription factor upstream transcription factor 1 expression [
14]. Another key regulator of phospholipid metabolism, lysophosphatidylcholine acyltransferase 3 (LPCAT3), is an enzyme predominantly expressed in the liver. LPCAT3 exhibited differential expression between HBV-infected and functionally cured patients, suggesting its involvement in HBV disease progression. Moreover, LPCAT3 inhibition enhanced endoplasmic reticulum stress and HBV replication, further supporting the link between HBV-mediated inflammation and lipid metabolism dysregulation [
15].
Glycogen synthase kinase 3, a regulator of glucose homeostasis, induces phosphorylation of the transcription factor forkhead box K2, which directly binds to HBV cccDNA, thereby promoting HBV transcription [
16,
17]. Yang et al. [
18] found that sterol regulatory element-binding protein 2 (SREBP2), a key transcription factor involved in intracellular sterol metabolism, was downregulated in peripheral blood mononuclear cells from HBV-infected patients compared to healthy controls. The authors demonstrated that SREBP2 inhibits HBV replication by suppressing HBx nuclear translocation, a critical step in viral gene expression, providing evidence of metabolic factor-mediated regulation of HBV replication [
18].
In the current issue of
Clinical and Molecular Hepatology, Cheng et al. [
19] identified a metabolic host factor involved in the transcription of HBV cccDNA, revealing how glutaminolysis influences viral epigenetic regulation and proposing a novel mechanism for therapeutic intervention. The authors elucidated a novel mechanism by which the HBV antigen facilitates the translocation of glutamate dehydrogenase 1 (GDH1), leading to increased glutaminolysis in the nucleus. Nuclear GDH1 subsequently triggers the accumulation of α-Ketoglutarate, which epigenetically activates lysine-specific demethylase KDM4A, inducing the demethylation of cccDNA and thereby promoting HBV transcription. This study identified a novel intracellular metabolic alteration that epigenetically enhances the HBV lifecycle and suggested a potential therapeutic approach to suppress HBV transcription
in vitro and
in vivo through glutamine deprivation and epigallocatechin gallate, a GDH1 inhibitor [
19]. This study provides direct evidence that HBV-regulated metabolites influence HBV replication. Thus, it suggests that metabolic regulation may play a role in HBV replication.
FOOTNOTES
-
Authors’ contribution
HJ Cho drafted the manuscript. SG Park edited and finalized the manuscript.
-
Acknowledgements
This research was supported by the Korea Health Industry Development Institute (KHIDI) (RS-2024-00335243), and by the National Research Foundation of Korea (NRF-2021R1A2C3011211 and NRF-2022M3A9I2017587). The authors acknowledge the use of AI-assisted technology (ChatGPT, OpenAI, February 2025 version) for language refinement, including grammar and vocabulary suggestions. The AI was employed solely for linguistic assistance and did not contribute to the conceptualization, analysis, or interpretation of the manuscript. The authors take full responsibility for the accuracy and integrity of the content.
-
Conflicts of Interest
The authors have no conflicts to disclose.
Table 1.Host factors related to HBV-mediated metabolic alterations
Table 1.
|
Host factors |
Mechanisms |
|
HBV-mediated disease progression |
|
PKM2 |
HBV large S antigen affects PKM2 oligomerization, increasing glucose consumption and lactate production and induces metabolic switch from oxidative phosphorylation to aerobic glycolysis. |
|
Bile acid, sphingolipid metabolites |
Bile acid and Sphingolipid metabolites activate MAPK/mTOR pathway in the hepatocellular carcinoma, augmenting the primary bile acid synthesis and sphingolipids metabolism in turn. |
|
Bip |
HBV small S antigen triggers ER stress by hijacking Bip, promoting disorders of lipid metabolism. |
|
SphK1 |
SphK1 and S1P was elevated in liver tissues of HBV-positive hepatocellular carcinoma patients. |
|
LPCAT3 |
As a pivotal regulator of LPC and PC modulation, LPCAT3 is significantly correlated with HBV replication and may promote inflammation by exacerbating endoplasmic reticulum stress. |
|
Regulation of HBV replication |
|
GSK3 |
GSK3 phosphorylates the transcription activator FOXK2, which binds to HBV DNA |
|
SREBP2 |
SREBP2 inhibits HBV replications by interacting directly with the HBx protein |
|
GDH1 |
HBcAg facilitates the nuclear translocation of GDH1, increasing α-KG levels by glutaminolysis. Increased α-KG activates histone lysine demethylase KDM4A, decreasing methylation of cccDNA |
Abbreviations
binding immunoglobulin protein
glutamate dehydrogenase 1
lysophosphatidylcholine acyltransferase 3
sterol regulatory element-binding protein 2
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