DIFFERENT PREVALENCE OF PRECORE MUTANTS IN 5 MEMBERS OF A HEPATITIS-B-VIRUS-INFECTED FAMILY - EVIDENCE FOR A PRECORE VARIANT TYPE IN AN ASYMPTOMATIC ANTI-HBS PATIENT

Chronic active hepatitis B (CAH-B), anti-HBe (+) has been associated with a hepatitis B virus variant carrying a stop codon at the distal pre-C region that prevents HBeAg synthesis. We analyzed the HBV DNA pre-C region in five members of a Turkish family. The mother presented an anti-HBe (+) CAH-B and the four children different hepatitis B virus serological and clinical profiles. The pre-C region was analyzed by cloning after DNA amplification in sera and peripheral blood mononuclear cells. A method for rapid screening of a large number of cloned polymerase chain reaction products was developed for the presence of the most frequent pre-C mutations (G to A substitution at nucleotide position 1896 and 1899). At least 60 independent clones were tested for each patient by selective oligonucleotide hybridization using non-mutated (M0), one (M1) and two (M2) point-mutated probes. Results were confirmed by sequencing. The mutation 1896 was present in 91% of DNA clones from the mother. The same mutation was also found in 85% of the clones in the youngest child (D), but in less than 10% of the clones from children A and C. Only the pre-C wild-type strain was observed in child B. X gene deletions (3 to 20 nt) were also present in some clones from the mother and children A, B and C. No significant difference between serum and peripheral blood mononuclear cells concerning the viral population was observed. In this study, a method for rapid screening of numerous polymerase chain reaction clones was developed to obtain the best quantitative estimation of mutated to wild-type HCV ratio present in patients. The data suggest: 1) a different selection of precore defective mutant virus between the members of the family, 2) the presence of pre-C mutant strains in an anti-HBs positive asymptomatic patient, and 3) the presence of X gene deletions associated to pre-C stop codon. Further investigation will be required to determine the influence of these genomic defects on the pathogenicity of the hepatitis B virus strains present in the patients. (C) Journal of Hepatology.