title: Hepatitis B surface antigen genetic elements critical for immune escape correlate with hepatitis B virus reactivation upon immunosuppression.
abstract: Hepatitis B virus (HBV) reactivation during immunosuppression can lead to severe acute hepatitis, fulminant liver failure, and death. Here, we investigated hepatitis B surface antigen (HBsAg) genetic features underlying this phenomenon by analyzing 93 patients: 29 developing HBV reactivation and 64 consecutive patients with chronic HBV infection (as control). HBsAg genetic diversity was analyzed by population-based and ultradeep sequencing (UDS). Before HBV reactivation, 51.7% of patients were isolated hepatitis B core antibody (anti-HBc) positive, 31.0% inactive carriers, 6.9% anti-HBc/anti-HBs (hepatitis B surface antibody) positive, 6.9% isolated anti-HBs positive, and 3.4% had an overt HBV infection. Of HBV-reactivated patients, 51.7% were treated with rituximab, 34.5% with different chemotherapeutics, and 13.8% with corticosteroids only for inflammatory diseases. In total, 75.9% of HBV-reactivated patients (vs. 3.1% of control patients; P<0.001) carried HBsAg mutations localized in immune-active HBsAg regions. Of the 13 HBsAg mutations found in these patients, 8 of 13 (M103I-L109I-T118K-P120A-Y134H-S143L-D144E-S171F) reside in a major hydrophilic loop (target of neutralizing antibodies [Abs]); some of them are already known to hamper HBsAg recognition by humoral response. The remaining five (C48G-V96A-L175S-G185E-V190A) are localized in class I/II-restricted T-cell epitopes, suggesting a role in HBV escape from T-cell-mediated responses. By UDS, these mutations occurred in HBV-reactivated patients with a median intrapatient prevalence of 73.3% (range, 27.6%-100%) supporting their fixation in the viral population as a predominant species. In control patients carrying such mutations, their median intrapatient prevalence was 4.6% (range, 2.5%-11.3%; P<0.001). Finally, additional N-linked glycosylation (NLG) sites within the major hydrophilic loop were found in 24.1% of HBV-reactivated patients (vs. 0% of chronic patients; P<0.001); 5 of 7 patients carrying these sites remained HBsAg negative despite HBV reactivation. NLG can mask immunogenic epitopes, abrogating HBsAg recognition by Abs.
  
  
  CONCLUSIONS
  HBV reactivation occurs in a wide variety of clinical settings requiring immune-suppressive therapy, and correlates with HBsAg mutations endowed with enhanced capability to evade immune response. This highlights the need for careful patient monitoring in all immunosuppressive settings at reactivation risk and of establishing a prompt therapy to prevent HBV-related clinical complications.
authors.affiliation: Department of Experimental Medicine and Surgery, University of Rome Tor Vergata, Rome, Italy.
authors.forename: Romina
authors.initials: R
authors.lastname: Salpini
authors.forename: Luna
authors.initials: L
authors.lastname: Colagrossi
authors.forename: Maria Concetta
authors.initials: MC
authors.lastname: Bellocchi
authors.forename: Matteo
authors.initials: M
authors.lastname: Surdo
authors.forename: Christina
authors.initials: C
authors.lastname: Becker
authors.forename: Claudia
authors.initials: C
authors.lastname: Alteri
authors.forename: Marianna
authors.initials: M
authors.lastname: Aragri
authors.forename: Alessandra
authors.initials: A
authors.lastname: Ricciardi
authors.forename: Daniele
authors.initials: D
authors.lastname: Armenia
authors.forename: Michela
authors.initials: M
authors.lastname: Pollicita
authors.forename: Fabiola
authors.initials: F
authors.lastname: Di Santo
authors.forename: Luca
authors.initials: L
authors.lastname: Carioti
authors.forename: Yoram
authors.initials: Y
authors.lastname: Louzoun
authors.forename: Claudio Maria
authors.initials: CM
authors.lastname: Mastroianni
authors.forename: Miriam
authors.initials: M
authors.lastname: Lichtner
authors.forename: Maurizio
authors.initials: M
authors.lastname: Paoloni
authors.forename: Mariarosaria
authors.initials: M
authors.lastname: Esposito
authors.forename: Chiara
authors.initials: C
authors.lastname: D'Amore
authors.forename: Aldo
authors.initials: A
authors.lastname: Marrone
authors.forename: Massimo
authors.initials: M
authors.lastname: Marignani
authors.forename: Cesare
authors.initials: C
authors.lastname: Sarrecchia
authors.forename: Loredana
authors.initials: L
authors.lastname: Sarmati
authors.forename: Massimo
authors.initials: M
authors.lastname: Andreoni
authors.forename: Mario
authors.initials: M
authors.lastname: Angelico
authors.forename: Jens
authors.initials: J
authors.lastname: Verheyen
authors.forename: Carlo-Federico
authors.initials: CF
authors.lastname: Perno
authors.forename: Valentina
authors.initials: V
authors.lastname: Svicher
mesh_terms: D000328:Adult; D000368:Aged; D024882:Drug Resistance, Viral; D005260:Female; D006031:Glycosylation; D006510:Hepatitis B Antibodies / Q000097:blood; D006514:Hepatitis B Surface Antigens / Q000235:genetics*; D006515:Hepatitis B virus / Q000502:physiology; D019694:Hepatitis B, Chronic / Q000188:drug therapy / Q000276:immunology* / Q000821:virology; D006801:Humans; D057131:Immune Evasion; D007165:Immunosuppression Therapy; D008297:Male; D008875:Middle Aged; D009154:Mutation; D014775:Virus Activation
chemical_list: D006510:Hepatitis B Antibodies; D006514:Hepatitis B Surface Antigens