However, no matter where it came from, whether bacterial, yeast or mammalian, the ssRNA encapsidated within HBcAg did function as a TLR7 ligand at the T and B cell levels with TLR7 knock-out mice verification14, indicating HBcAg packaged ssRNA could activate TLR7 signaling pathway in HBV natural infection. Here, TLR7 is linked to infection.