摘要
应用聚合酶链（ＰＣＲ）方法，分别扩增乙型肝炎病毒（ＨＢＶ）标志为ＨＢｓＡｇ（＋）、ＨＢｅＡｇ（＋）、抗ＨＢｃ（＋）的慢性乙型肝炎（ＣＨＢ）１８例（第一组），ＨＢＶ标志为ＨＢｓＡｇ（＋）、抗ＨＢｅ（＋）和抗ＨＢｃ（＋）的慢性乙型肝炎２１例（第二组），以及ＨＢＶ标志与第二组相同的体检健康的正常人１５例（第三组）。其ＰＣＲ的阳性率分别为８３．３％，７１．４％和３３．３％。第二组与第三组相比有显著差异（Ｐ＜０．０５），提示病毒的复制与病情活动有关。对ＰＣＲ扩增后阳性的３０例进行克隆测序分析，发现有５例前核心区基因有变异，均见于第二组病例中。第一组病例无穷变株出现，二组相比有显著差异（Ｐ＜０．０５）。其突变情况为：２例１８９８位Ｇ→Ａ突变，其中１例临床表现为重型肝炎，１例为１９０１位Ｇ→Ａ突变，１例为１８９１位Ｔ→Ｃ突变，另１例为１８３９位Ａ→Ｇ突变。后二种突变形式目前尚未见报道，所有这些均表明ＨＢＶ标志为ＨＢ－ｓＡｇ（＋）、抗ＨＢｅ（＋）和抗ＨＢｃ（＋）的慢乙肝病例，ＨＢＶ前核心区基因变异的发生率较高，可能与病毒迫于机体免疫压力所产生的免疫逃避有关。
9
cases of chronic hepatitis B and 15 cases of“healthy person”with
positive sera HBsAg,Anti-HBe and Anti-HBc were studied by HBV DNA
PCR.18 cases of chronic hepatit is B with positive sera HBsAg,HBeAg
and anti-HBc were assigned to the first group(group l),21 cases of
chronic hepatitis B with positive sera HBsAg,anti-HBe and anti-HBc to
the second group(group 2).15 cases of asymp- tomatic healthy carriers
with positive sera HBsAg,anti-HBe and anti-HBc to the third
group(group 3),The PCR positive rates of them were 83.3%,71.4% and
33.3% respectively. There was statistically dif- ference between
group 2 and group 3.All those results suggested that recurrence of
hepatitis were associ- ated with replication of HBV-DNA( by PCR).30
samples of HBV-DNA produced by PCR from sera of both group l and 2
were cloned into bacteriophage M13mpl8 or plasmid PBS and sequenced.5
cases had point mutants, all found in group 2. There was
significant difference in mutants between group l and 2.Two cases had
G to A point mutant in l898,tryptophane to translational stop codon,
One G to A in 1901 of replaces Glycine to Aspartic acid, another T to
C in l989 of Tryptophane by Arginine,last in 1839,which converts A to
G. All the above results demonstrate that patients with positive sera
HBsAg,anti-HBc and anti-HBe have high incidence of mutant,which might
be assiated with immune escape.
