title: Molecular characterization of a variant virus that caused de novo hepatitis B without elevation of hepatitis B surface antigen after chemotherapy with rituximab.
abstract: 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.
authors.affiliation: Molecular Gastroenterology and Hepatology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Masami
authors.initials: M
authors.lastname: Miyagawa
authors.forename: Masahito
authors.initials: M
authors.lastname: Minami
authors.forename: Kota
authors.initials: K
authors.lastname: Fujii
authors.forename: Rei
authors.initials: R
authors.lastname: Sendo
authors.forename: Kojiro
authors.initials: K
authors.lastname: Mori
authors.forename: Daisuke
authors.initials: D
authors.lastname: Shimizu
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Nakajima
authors.forename: Kohichiroh
authors.initials: K
authors.lastname: Yasui
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Itoh
authors.forename: Masafumi
authors.initials: M
authors.lastname: Taniwaki
authors.forename: Takeshi
authors.initials: T
authors.lastname: Okanoue
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Yoshikawa
mesh_terms: D000368:Aged; D000911:Antibodies, Monoclonal / Q000009:adverse effects* / Q000627:therapeutic use*; D058846:Antibodies, Monoclonal, Murine-Derived; D045744:Cell Line, Tumor; D003001:Cloning, Molecular; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics; D006509:Hepatitis B / Q000821:virology*; D006514:Hepatitis B Surface Antigens / Q000096:biosynthesis / Q000097:blood*; D006515:Hepatitis B virus / Q000235:genetics* / Q000254:growth & development / Q000302:isolation & purification*; D022781:Hepatocytes / Q000821:virology; D006801:Humans; D008297:Male; D020125:Mutation, Missense; D011995:Recombination, Genetic; D000069283:Rituximab; D017422:Sequence Analysis, DNA; D014162:Transfection; D014775:Virus Activation; D014779:Virus Replication
chemical_list: D000911:Antibodies, Monoclonal; D058846:Antibodies, Monoclonal, Murine-Derived; D004279:DNA, Viral; D006514:Hepatitis B Surface Antigens; D000069283:Rituximab