Miyagawa Masami, Minami Masahito, Fujii Kota, Sendo Rei, Mori Kojiro, Shimizu Daisuke, Nakajima Tomoaki, Yasui Kohichiroh, Itoh Yoshito, Taniwaki Masafumi, Okanoue Takeshi, Yoshikawa Toshikazu
Molecular Gastroenterology and Hepatology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
J Med Virol. 2008 Dec;80(12):2069-78. doi: 10.1002/jmv.21311.
Hepatitis B virus (HBV) reactivation in hepatitis B surface antigen (HBsAg)-negative patients following treatment with rituximab has been reported increasingly. The aim of this study was to investigate the molecular mechanisms underlying HBV reactivation in an HBsAg-negative patient. HBV was reactivated in a 75-year-old man following chemotherapy with rituximab, without elevation of HBsAg. The patient's full-length HBV genome was cloned and the entire sequence was determined. Transfection studies were performed in vitro using recombinant wild-type HBV (wild-type), the patient's HBV (patient), and two chimeric HBV constructs, in which the preS/S region of the patient and wild-type virus had been exchanged with one another. Secreted HBsAg and intra- and extra-cellular HBV DNA were measured. The number of amino acid substitutions in HBV from this patient was much higher than in previous reports of HBV mutants, such as occult HBV and vaccine escape HBV mutants. Levels of HBsAg and HBV DNA production in vitro were significantly lower in the patient compared to wild-type transfections. From analyses of the chimeric constructs, the altered preS/S region was responsible mainly for this impairment. These results show that highly mutated HBV can reactivate after chemotherapy with rituximab, despite an unusually large number of mutations, resulting in impaired viral replication in vitro. Severe immune suppression, probably caused by rituximab, may permit reactivation of highly mutated HBV. These findings have important clinical implications for the prevention and management of HBV reactivation and may explain partially the mechanism of recent, unusual cases of HBV reactivation.
越来越多的报道称，接受利妥昔单抗治疗的乙肝表面抗原（HBsAg）阴性患者会出现乙型肝炎病毒（HBV）再激活。本研究旨在探讨一名HBsAg阴性患者HBV再激活的分子机制。一名75岁男性在接受利妥昔单抗化疗后出现HBV再激活，而HBsAg未升高。克隆了该患者的全长HBV基因组并测定了其完整序列。使用重组野生型HBV（野生型）、患者的HBV（患者型）以及两种嵌合HBV构建体进行体外转染研究，在这两种嵌合构建体中，患者型和野生型病毒的前S/S区域相互进行了交换。检测了分泌的HBsAg以及细胞内和细胞外的HBV DNA。该患者HBV中的氨基酸替代数量远高于以往关于HBV突变体（如隐匿性HBV和疫苗逃逸HBV突变体）的报道。与野生型转染相比，患者型体外的HBsAg和HBV DNA产生水平显著降低。通过对嵌合构建体的分析，前S/S区域的改变是造成这种损害的主要原因。这些结果表明，高度突变的HBV在接受利妥昔单抗化疗后仍可再激活，尽管存在异常大量的突变，导致其在体外的病毒复制受损。利妥昔单抗可能导致的严重免疫抑制，可能会使高度突变的HBV再激活。这些发现对HBV再激活的预防和管理具有重要的临床意义，并且可能部分解释近期不寻常的HBV再激活病例的机制。
