Pre-S1 proteins in sera of patients positive for HBsAg and antibodies to hepatitis delta virus.

Infection with the hepatitis Delta virus results in a reduction in hepatitis B virus replication. To study the question as to whether expression of large surface (pre-S1) protein is changed in patients with previous and chronic hepatitis Delta virus infection, sera of 25 HBsAg- and anti-HD-positive patients were analyzed by the Western blot technique using an antibody directed against a pre-S1 fusion protein. Pre-S1 proteins were present only in 3 of the 25 sera. This finding suggests that the expression of pre-S1 proteins and HBsAg is regulated independently, and that pre-S1 proteins are not necessarily required for the envelope of hepatitis Delta virus.