NATURALLY-OCCURRING CORE-GENE-DEFECTIVE HEPATITIS-B VIRUSES

This study was undertaken to determine the prevalence of core-gene-def ective hepatitis B virus (HBV) in patients with chronic HBV infection, and the nature and significance of the deletions. PCR was performed o n sera from 263 patients with chronic HBV infection. Seventeen (6.5%) patients had smaller band(s) in addition to a band of the expected siz e. Additional bands were also detected in the follow-up samples from 8 0% and 3% patients who had respectively, multiple and single bands ini tially. Six patients were further studied by direct sequencing. Four p atients had in-frame deletions leading to loss of codons 79-122 of the core gene. Two patients had identical frameshift deletions of nucleot ides 2204-2333 resulting in the loss of the first nine codons of the o verlapping P gene. Follow-up samples from three of four patients studi ed showed deletions identical to those in the initial samples. The per sistence of these deletions suggests that they were stable and that th ey may contribute to the chronicity of infection.