Abstract
OBJECTIVE: Hepatitis B virus (HBV) is a globally distributed infectious disease affecting the liver. This literature review aims to summarize all available relevant information on the PubMed database about HBV's connection to the microbiome and to consider possible treatment adjuncts. MATERIALS AND METHODS: Database used: PubMed. Keywords used: "HBV", "Hepatitis B", "microbiome". In the PubMed database, 179 research publications were identified using these keywords; 69 studies were excluded as they were irrelevant or retracted. Of the remaining, 110 were analyzed in this literature review, and four additional literature sources were used to supply background information and context. Information was summarized. The analysed studies in total included 14,814 participants (excluding animal studies), of whom 8564 were HBV-infected individuals. RESULTS: Results characterizing abundance or decrease in specific bacterial, viral, and fungal species are heterogeneous; multiple studies support that the HBV patient oral and fecal microbiome is different from that in healthy controls (HCs) and varies throughout disease progression. The HBV seems to transform the microbiome negatively, leading to dysbiosis and decreased microbial diversity in most studies. Evidence links HBV microbiome changes with influence on HbeAg seroconversion, HBV-DNA load, metabolic pathways, liver cirrhosis, and hepatocellular carcinoma. The research proposes that members of microbiota could potentially promote or protect against liver injury in HBV. Four studies proposed that the plasma virome in HBV patients was primarily composed of members of the Anelloviridae. One study researched a parasite (Entamoeba gingivalis) in HBV patients. Two studies analyzed HBV patients' fungal profiles. CONCLUSIONS: Microbiota research, although promising, at the present moment is heterogeneous. HBV patients' microbiota is distinguishable from HCs, and multiple studies have tried to identify the HBV characteristic microbiome; however, more precise information is needed to draw conclusions. Fecal microbiota transplantation and probiotics have the potential to be therapy adjuncts for HBV patients, but more research is needed.