以乙型肝炎病毒（ＨＢＶ）Ｘ基因序列的异质性表现来探讨ＨＢＶ准种在　慢性感染者中的存在状态。以中国株ＨＢＶ基因序列为依据，设计特异性多聚酶链反应引物，　自９例慢性ＨＢＶ感染患者血清中扩增ＨＢＶ　Ｘ基因，克隆入ｐＧＥＭ　Ｔｅａｓｙ质粒，随机挑选克隆进行Ｄ　ＮＡ测序以确定病毒的变异程度。３７例测序结果提示来源于不同患者ＨＢＶ　Ｘ基因序列高度保守　，但每个序列均不一致。Ｘ区除了存在广泛的碱基点替换突变外，序列的缺失突变占测序克　隆总数的５１．４％（１９／３７）；氨基酸缺失及移框突变多发生于１２３位氨基酸残基之后，可导致Ｘ蛋　白多种羧基端形式。结果提示ＨＢＶ长期携带者体内有ＨＢＶ准种共存，Ｘ区内存在热点缺失突变区，该区突变结果可能影响Ｘ蛋白反式激活功能。

The HBV genetic heterogeneity in the patients with chroni c HBV infection was reported in this article. A set of spectific primers was syn thesized according to HBV DNA sequence of Chinese strain, the whole X region was amplified by PCR method from the serum of 9 patients with chronic HBV infection , and then the PCR products were subcloned into pGEM Teasy vectors. Clones were randomly selected to be sequenced. Comparison of the cloned sequence was made to find the difference. After being compared, each sequence of selected clones is o f difference. The point mutation scattered through X region. Deletion mutations were detected in 19 clones of 37(51.4%), which caused different carboxyl endings of X protein. There is a hot region (after 123 aa code) where deletion mutation frequently happens. There were HBV quasispecies groups in sera from patients wi t h chronic HBV infection. There was a hot deletion region near the 3’ end of X ge ne, resulting in losing its transactivating activity