FULMINANT REACTIVATION OF HEPATITIS-B DUE TO ENVELOPE PROTEIN MUTANT THAT ESCAPED DETECTION BY MONOCLONAL HBSAG ELISA

The detection of a fatal case of reactivation of hepatitis B, in a pre viously vaccinated Indonesian patient after withdrawal of chemotherapy for lymphoma, was delayed because HBsAg was negative in a widely used monoclonal-antibody-based ELISA. The serum was later found to be stro ngly reactive for HBsAg by the polyclonal radioimmunoassay and for HBV DNA. PCR sequencing revealed a substitution of arginine for glycine a t position 145 of HBsAg in the major neutralising epitope cluster, the a determinant, as well as a 2-aminoacid insertion of asparagine and t hreonine between positions 122 and 123, immediately upstream of this d eterminant.