Determination of hepatitis B virus genotype G by polymerase chain reactionwith hemi-nested primers

Hepatitis B virus (HBV) has been classified into six genotypes designated A -F by sequence divergence in the entire genome exceeding 8%. Very recently, the seventh genotype was reported and named genotype G. HBV genotype G is distinct from genomes of the other six genotypes in that it possesses an in sertion of 36 nucleotides in the core gene, and has been found so far in Fr ance and the United States. A method for determining HBV genotype G was dev eloped by polymerase chain reaction (PCR) with primers deduced from the 36- nucleotide (nt) insertion in five isolates of HBV genotype G the sequences of which have been deposited in DNA databases. The validity of this method, for specifically detecting HBV genotype G, was verified on panel consistin g of 142 HBV isolates of six major genotypes and four of genotype G. A tota l of 540 sera containing HBV in Japan covering symptom free carriers and pa tients with a spectrum of chronic liver disease were tested by this method, but not a single HBV genotype G sample was found. A possible method for se rological determination of hepatitis B surface antigen of genotype G is sug gested, without amplification or sequencing nucleotides, which would expand epidemiological and clinical researches on HBV genotype G. (C) 2001 Elsevi er Science B.V. All rights reserved.