BACKGROUND The incidence of mixed hepatitis C virus (HCV) genotype infection is variable, and a few reports exist regarding the efficacy of direct-acting antivirals (DAA) therapy for mixed genotype. We aimed to investigate the prevalence of mixed genotype and its impact on the virologic response to DAA therapy. METHODS A total of 365 patients with chronic HCV infection who completed antiviral therapy were recruited. Nested polymerase chain reaction with universal and specific primers of genotypes 1b and 2 and direct sequencing were used for HCV genotyping. RESULTS Direct sequencing with universal primers defined genotypes 1b (n = 230), 2a (n = 95), and 2b (n = 40). Direct sequencing of genotype 2 was performed in patients with genotype 1b, and direct sequencing of genotype 1b in patients with genotype 2. Four patients with genotype 1b underwent amplification for genotype 2, and direct sequencing identified genotypes 1b (n = 1), 2a (n = 1), and 2b (n = 2). None with genotype 2 underwent amplification for genotype 1b. Three cases were confirmed to have mixed genotype. CONCLUSIONS Mixed genotype was rare, and hence the impact of mixed genotype on treatment outcome with DAA therapy is expected to be minimal.

中文翻译：

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混合型丙型肝炎病毒基因型感染的流行及其对直接作用抗病毒治疗反应的影响。

背景技术混合型丙型肝炎病毒（HCV）基因型感染的发生率是可变的，关于直接作用抗病毒剂（DAA）治疗混合型基因型的功效已有一些报道。我们旨在调查混合基因型的流行及其对DAA疗法的病毒学应答的影响。方法招募了365名完成抗病毒治疗的慢性HCV感染患者。巢式聚合酶链式反应与通用和特定的基因型1b和2的引物和直接测序用于HCV基因分型。结果用通用引物直接测序确定了基因型1b（n = 230），2a（n = 95）和2b（n = 40）。基因型1b的患者进行基因型2的直接测序，基因型2的患者进行基因型1b的直接测序。基因型1b的四名患者接受了基因型2的扩增，直接测序鉴定出基因型1b（n = 1），2a（n = 1）和2b（n = 2）。没有对基因型2进行基因型1b扩增。确认3例具有混合基因型。结论混合基因型很少见，因此混合基因型对DAA治疗效果的影响预计很小。