title: Posttranslational modifications and secretion efficiency of immunogenic hepatitis B virus L protein deletion variants.
abstract: BACKGROUND
  Subviral particles of hepatitis B virus (HBV) composed of L protein deletion variants with the 48 N-terminal amino acids of preS joined to the N-terminus of S protein (1-48preS/S) induced broadly neutralizing antibodies after immunization of mice with a Semliki Forest virus vector. A practical limitation for use as vaccine is the suboptimal secretion of such particles. The role of the N-terminal preS myristoylation in the cellular retention of full-length L protein is described controversially in the literature and the relation of these data to the truncated L protein was unknown. Thus, we studied the effect of preS myristoylation signal suppression on 1-48preS/S secretion efficiency, glycosylation and subcellular distribution.
  
  
  RESULTS
  The findings are that 1-48preS/S is secreted, and that removal of the N-terminal myristoylation signal in its G2A variant reduced secretion slightly, but significantly. The glycosylation pattern of 1-48preS/S was not affected by the removal of the myristoylation signal (G2A mutant) but was different than natural L protein, whereby N4 of the preS and N3 of the S domain were ectopically glycosylated. This suggested cotranslational translocation of 1-48preS in contrast to natural L protein. The 1-48preS/S bearing a myristoylation signal was localized in a compact, perinuclear pattern with strong colocalization of preS and S epitopes, while the non-myristoylated mutants demonstrated a dispersed, granular cytoplasmic distribution with weaker colocalization.
  
  
  CONCLUSIONS
  The large deletion in 1-48preS/S in presence of the myristoylation site facilitated formation and secretion of protein particles with neutralizing preS1 epitopes at their surface and could be a useful feature for future hepatitis B vaccines.
authors: Biomedical Research and Study Centre, Ratsupites street 1, Riga, Latvia. baiba@biomed.lu.lv
authors: Baiba
authors: B
authors: Niedre-Otomere
authors: Ance
authors: A
authors: Bogdanova
authors: Ruta
authors: R
authors: Bruvere
authors: Velta
authors: V
authors: Ose
authors: Wolfram H
authors: WH
authors: Gerlich
authors: Paul
authors: P
authors: Pumpens
authors: Dieter
authors: D
authors: Glebe
authors: Tatjana
authors: T
authors: Kozlovska
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood; D000956:Antigens, Viral / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D017353:Gene Deletion; D005822:Genetic Vectors; D006510:Hepatitis B Antibodies / Q000097:blood; D017325:Hepatitis B Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D006515:Hepatitis B virus / Q000235:genetics / Q000276:immunology*; D051379:Mice; D009500:Neutralization Tests; D011499:Protein Processing, Post-Translational; D012672:Semliki forest virus / Q000235:genetics; D014759:Viral Envelope Proteins / Q000235:genetics*
chemical_list: D057134:Antibodies, Neutralizing; D000956:Antigens, Viral; D006510:Hepatitis B Antibodies; D017325:Hepatitis B Vaccines; C096362:L protein, hepatitis B virus; D014759:Viral Envelope Proteins