HBcAg (core antigen) is a hepatitis B virus protein. It is an indicator of active viral replication, which means that a person infected with hepatitis B can easily spread the virus to another person. HBeAg is the extracellular form of hepatitis B surface antigen (HBcAg), both of which are markers of viral replication, and antibodies against these antigens are markers of decreased replication. The same DNA sequence yields a wide range of protein products. When "ORF Core" and "Pre C" are translated together, "HBeAg" is generated. While HBcAg is considered "granular" and "HBeAg" is considered "non-granular" or "secreted". HBeAg and HBcAg are derived from the same reading frame, HBeAg is secreted from cells and accumulates in serum as immunologically distinct soluble antigens. HBeAg is secreted and found in the patient's serum and can be used as a marker of active replication in chronic hepatitis. Although the function of HBeAg is not fully understood, it has been shown to downregulate Toll-like receptor 2 expression in hepatocytes and monocytes, resulting in a decrease in cytokine expression. HBeAg is dispensable for replication, and mutant viruses with defects in the pre-C region remain infectious and pathogenic.