对同一地区两例输血后丙型肝炎进行ＰＣＲ分型，结果为Ⅱ型。分别将其ＮＳ５区基因部分片段克隆到ｐＵＣ１８和Ｍ１３ｍｐ１８中，序列分析结果表明在ＮＳ５区基因相同区段，二者的核苷酸同源性为８９．０４％，氨基酸同源性为９０．７５％。而且在分离株Ｖ中第７０～７２位发现阅读框内终止密码子ＴＧＡ。与Ⅱ型代表株ＨＣＶＢＫ序列相比，相同区段的核苷酸和氨基酸同源性分别为：９１．５％，９１．９２％和９１．９１％，９１．９１％。对比分析表明，在同一地区基因型相同的不同分离株间ＮＳ５区基因仍存在较大变异，分离株Ｖ可能为缺陷性病毒 Two cases of hepatitis C in the same area after transfusion were genotyped by PCR. The fragment of NS5 region was cloned into pUC18 and M13mp18, respectively. Sequence analysis showed that the homology of nucleotide and amino acid in the NS5 region was 89.04% and 90.75 %. In addition, the stop codon TGA in reading frame was found at the 70-72 position in isolate V. The nucleotide and amino acid homology of the same segment was 91.5%, 91.92% and 91.91%, 91.91%, respectively, compared with the HCVBK sequence of the type Ⅱ representative strain. Comparative analysis showed that there was still a large variation in the NS5 gene between different genotypes of the same genotype in the same region, and isolate V may be a defective virus