OCCURRENCE OF HEPATITIS-DELTA VIRUS-INFECTION IN HEPATITIS-B VIRUS-INFECTED PATIENTS WITH DIFFERENT SERUM PATTERNS OF PRES GENE-ENCODED PROTEINS

The occurence of delta superinfection among viremic and nonviremic HbsAg-positive carriers with different serum patterns and levels of preS1 and preS2 antigens was investigated. PreS1 and preS2 antigens in serum, as well as their levels, were found to be independent of hepatitis B virus (HBV) replicative activity. Serological evidence of hepatitis delta virus (HDV) superinfection was found in 34 out of 233 (14.6%) HBsAg-positive carriers; all these 34 patients resulted positive for antibody to hepatitis B 'e' antigen, and 33 of them were negative for circulating HBV-DNA. Delta superinfection occurred only among HBsAg-positive carriers whose sera were reactive for both preS1 and preS2 antigens (30 out of 142; 21.1%) or at least for preS1 alone (4 out of 63; 6.3%), but not among the patients with undetectable levels of both these antigens. Serum levels of both preS1 (p < 0.005) and preS2 (p < 0.001) antigens were found to be significantly higher in delta-positive HBsAg-positive carriers than in patients with HBV infection uncomplicated by HDV. In addition to confirm previous observations that the detection of both preS antigens in HBsAg-positive sera is independent of HBV replication, these findings clearly show that HDV infection requires not only the presence of HBsAg, but also the presence of preS peptides, and seem to suggest a low susceptibility of HBsAg-positive carriers with low or undetectable synthesis and secretion of HBV surface proteins to delta superinfection.