Infection with hepatitis D virus (HDV; delta agent) can occur simultaneously with infection with hepatitis B virus (HBV) or in a carrier of hepatitis B virus because HDV is a defective virus that requires HBV for its replicative function. What serologic test can be used to determine whether a patient with HDV is an HBV carrier?

In a chronic HBV carrier, there would be no HB core IgM antibody, whereas it would be present in a new HBV infection. The HBe antigen could be present in either an HBV carrier or in acute infection. HBsAg would be present in either a new infection or in the carrier state, while HBsAb would not be present in either case. Reference: Ananthanarayan and Paniker&;s Textbook of Microbiology Tenth edition