Xu Simin, Doehle Brian, Rajyaguru Sonal, Han Bin, Barauskas Ona, Feng Joy, Perry Jason, Dvory-Sobol Hadas, Svarovskaia Evguenia S, Miller Michael D, Mo Hongmei
Gilead Sciences, Foster City, CA, USA.
Antivir Ther. 2017;22(7):587-597. doi: 10.3851/IMP3149. Epub 2017 Mar 1.
Sofosbuvir is a nucleoside analogue inhibitor of the HCV NS5B polymerase approved for treatment of HCV-infected patients in combination with ribavirin or with other antivirals. It has activity against all genotypes of HCV. Resistance to sofosbuvir in genotype-1 and -2 HCV is conferred by the S282T substitution in NS5B.
To begin to define the correlates of resistance to sofosbuvir in other genotypes, we performed selection experiments in cell culture using cell lines containing subgenomic replicons derived from genotypes-1b, -2a, -3a and -4a, or chimeric replicons in a genotype-1b background but encoding genotype-2b, -5a and -6a NS5B polymerase.
In every case, S282T was selected following passage in the presence of increasing concentrations of sofosbuvir for 10 to 15 weeks. When introduced as a site-directed mutant, S282T conferred reductions in sofosbuvir susceptibility of between 2.4 and 19.4-fold. Other substitutions observed during the selections had relatively less impact on susceptibility, such as N237S in genotype-6a (2.5-fold). Replication capacity was affected by the introduction of S282T in all genotypes to variable extents (3.2% to 22% of wild type).
These results confirm that S282T is the primary sofosbuvir resistance-associated substitution and that replication capacity is reduced when it is present in all genotypes of HCV.
索磷布韦是一种HCV NS5B聚合酶的核苷类似物抑制剂，已被批准与利巴韦林或其他抗病毒药物联合用于治疗HCV感染患者。它对所有HCV基因型均有活性。NS5B中的S282T替代导致1型和2型HCV对索磷布韦产生耐药性。
为了开始确定其他基因型对索磷布韦耐药性的相关因素，我们在细胞培养中进行了选择实验，使用含有源自1b型、2a型、3a型和4a型亚基因组复制子的细胞系，或在1b型背景下但编码2b型、5a型和6a型NS5B聚合酶的嵌合复制子。
在每种情况下，在存在递增浓度索磷布韦的情况下传代10至15周后均选择出了S282T。当作为定点突变引入时，S282T使索磷布韦敏感性降低2.4至19.4倍。在选择过程中观察到的其他替代对敏感性的影响相对较小，例如6a型中的N237S（2.5倍）。在所有基因型中，S282T的引入均不同程度地影响了复制能力（为野生型的3.2%至22%）。
这些结果证实S282T是主要的与索磷布韦耐药相关的替代，并且当它存在于所有HCV基因型中时复制能力会降低。
