Type-III interferon stimulated gene TRIM31 mutation in an HBV patient blocks its ability in promoting HBx degradation

TRIM5γ, together with TRIM31, has been shown to promote HBx ubiquitination and degradation. This study aimed to explore whether a patient with HCC (hepatic cell carcinoma) having a small nucleotide inserted into the TRIM31 gene, which made a shorter transcript stop at 768 bp, would result in blocking the activity of TRIM31 in promoting HBx degradation. Besides, this study aimed to determine the binding region of the TRIM31-TRIM5γ-HBx complex. HBV (Hepatitis B virus) infection was reported to induce type-III IFN but not type-I or type-II IFNs, here TRIM31 was found to be a type III rather than a type I stimulated gene, which was indispensable in inhibiting the hepatitis B virus replication by the interferon families. Thus, this study further identified the critical role of TRIM31 in the host-hepatitis B virus interaction.