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[Gene variation in the pre-C region of hepatitis B virus].

We examined the serum HBV DNA of the chronic hepatitis B patients with positive c-system by using polymerase chain reaction (PCR). Twenty samples of HBeAg(+)/anti-HBe(-) positive PCR products and 20 samples of HBeAg(-)/anti-HBe(+) positive PCR products were selected. These products were dot-hybridized by synthetic HBV pre-C region geno oligonucleotide probes M0 (non mutated), M1 (one) point-mutated), M2 (two point-mutated). The results thus obtained showed that for 85% (17/20) of the chronic hepatitis patients with HBeAg(-)/anti-HBe(+), point mutation occurred at the 1,896th nucleotide, resulting in the stop codon, and half (10/20) of the patients suffered two points mutation. The direct determination of the sequence of some mutation PCR products selected proved the existence of point mutation. The result indicated that the natural conversion of hepatitis patients' HBeAg(+) to anti-HBe(+) may have resulted from the genovariation in the pre-c region of HBVDNA rather than from the decreased of virus replication.