Targeting the hepatitis B virus precore antigen with a novel IgNAR single variable domain intrabody.
The Hepatitis B virus precore protein is processed in the endoplasmic reticulum (ER) into secreted hepatitis B e antigen (HBeAg), which acts as an immune tolerogen to establish chronic infection. Downregulation of secreted HBeAg should improve clinical outcome, as patients who effectively respond to current treatments (IFN-α) have significantly lower serum HBeAg levels. Here, we describe a novel reagent, a single variable domain (V(NAR)) of the shark immunoglobulin new antigen receptor (IgNAR) antibodies. V(NAR)s possess advantages in stability, size (~14 kDa) and cryptic epitope recognition compared to conventional antibodies. The V(NAR) domain displayed biologically useful affinity for recombinant and native HBeAg, and recognised a unique conformational epitope. To assess therapeutic potential in targeting intracellular precore protein to reduce secreted HBeAg, the V(NAR) was engineered for ER-targeted in vitro delivery to function as an intracellular antibody (intrabody). In vitro data from HBV/precore hepatocyte cell lines demonstrated effective intrabody regulation of precore/HBeAg.
Victorian Infectious Diseases Reference Laboratories, 10 Wreckyn Street, North Melbourne, Victoria 3051, Australia. renae.walsh@mh.org.au
Renae
R
Walsh
Stewart
S
Nuttall
Peter
P
Revill
Danni
D
Colledge
Liza
L
Cabuang
Sally
S
Soppe
Olan
O
Dolezal
Kate
K
Griffiths
Angeline
A
Bartholomeusz
Stephen
S
Locarnini
D001688:Biological Products / Q000276:immunology / Q000494:pharmacology; D002460:Cell Line; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000821:virology; D006510:Hepatitis B Antibodies / Q000276:immunology* / Q000494:pharmacology; D006513:Hepatitis B e Antigens / Q000276:immunology*; D006515:Hepatitis B virus / Q000276:immunology*; D022781:Hepatocytes / Q000821:virology; D006801:Humans; D008969:Molecular Sequence Data; D021381:Protein Transport; D017422:Sequence Analysis, DNA; D057127:Single-Chain Antibodies / Q000276:immunology* / Q000494:pharmacology
D001688:Biological Products; D006510:Hepatitis B Antibodies; D006513:Hepatitis B e Antigens; D057127:Single-Chain Antibodies