Alterations of the gut microbiome in chronic hepatitis B virus infection associated with alanine aminotransferase level

The changes in the gut microbiota of healthy hepatitis B virus (HBV) carriers, including asymptomatic and non-cirrhotic subjects, have been rarely scrutinized. From 1463 faecal samples in health examinees, in total 112 subjects, including 36 hepatitis B surface antigen (HBsAg)-positive and 76 control subjects, were included. Twenty-eight of 36 HBsAg-positive individuals (78%) showed normal alanine aminotransferase (ALT) levels (normal ALT group), whereas eight subjects exhibited elevated ALT levels (22%, high ALT group). By using 16S rRNA gene sequencing, the distance between normal and high ALT groups among HBsAg-positive subjects showed a significant separation after the pairwise comparison of weighted UniFrac distance (permutational analysis of variance q-value = 0.039), when compared with the distances to the control group. In comparison with the control group, the normal ALT group had Anaerostipes as a significant taxon that showed a positive association (Coefficient (Coef.) = 0.028, q = 0.039). Desulfovibrio (Coef. = 0.54, q = 0.014) and Megasphaera (Coef. = 1.41, q = 0.030) showed positive correlations, and Acidaminococcus (Coef. = −1.31, q = 4.15 × 10⁻⁷⁵) exhibited a negative correlation with high ALT level. Gut microbial composition was different according to HBV-induced serum ALT levels, indicative of a potential link between gut and liver metabolism.