College of Pharmacy, Sahmyook University, Hwarangro-815, Nowon-gu, Seoul, 139-742, Republic of Korea.
Bifidobacteria are considered one of the most beneficial probiotics and have been widely studied for their effects in preventing and treating specific pathological conditions. The present study explored the antiviral activity of Bifidobacterium adolescentis SPM0212 isolated from healthy Koreans against hepatitis B virus (HBV) and its mechanism of action. To determine the effect of B. adolescentis SPM0212 against HBV, the level of HBV surface antigen (HBsAg) in the culture medium and the levels of viral transcripts in HepG2.2.15 cells were measured by enzyme-linked immunosorbent assay and reverse transcription-quantitative PCR (RT-qPCR), respectively. To clarify the mechanism, we performed RT-qPCR using specific primers for genes encoding Interferon (IFN)-signaling components and IFN-inducible antiviral effectors. The cell extract of B. adolescentis SPM0212 dose-dependently decreased the extracellular HBsAg level by up to 50 %. Its gene expression in HepG2.2.15 cells was also inhibited by 40 %. This extract significantly increased the expression level of myxovirus resistance A, which is an IFN-inducible antiviral effector. Furthermore, the antiviral activity was observed in the fraction of compound(s) with molecular weights under 30 kDa. Thus, the cell extract of B. adolescentis SPM0212 inhibits HBV and its antiviral mechanism is associated with the Mx GTPase pathway.