Characterization of the hepatitis C virus E2 epitope defined by the broadly neutralizing monoclonal antibody AP33.
The mouse monoclonal antibody (MAb) AP33, recognizing a 12 amino acid linear epitope in the hepatitis C virus (HCV) E2 glycoprotein, potently neutralizes retroviral pseudoparticles (HCVpp) carrying genetically diverse HCV envelope glycoproteins. Consequently, this antibody and its epitope are highly relevant to vaccine design and immunotherapeutic development. The rational design of immunogens capable of inducing antibodies that target the AP33 epitope will benefit from a better understanding of this region. We have used complementary approaches, which include random peptide phage display mapping and alanine scanning mutagenesis, to identify residues in the HCV E2 protein critical for MAb AP33 binding. Four residues crucial for MAb binding were identified, which are highly conserved in HCV E2 sequences. Three residues within E2 were shown to be critical for binding to the rat MAb 3/11, which previously was shown to recognize the same 12 amino acid E2 epitope as MAb AP33 antibody, although only two of these were shared with MAb AP33. MAb AP33 bound to a panel of functional E2 proteins representative of genotypes 1-6 with higher affinity than MAb 3/11. Similarly, MAb AP33 was consistently more efficient at neutralizing infectivity by diverse HCVpp than MAb 3/11. Importantly, MAb AP33 was also able to neutralize the cell culture infectious HCV clone JFH-1. In conclusion, these data identify important protective determinants and will greatly assist the development of vaccine candidates based on the AP33 epitope.
The Institute of Infection, Immunity and Inflammation, School of Molecular Medical Sciences, The University of Nottingham, Queen's Medical Centre, Nottingham, NG7 2UH, UK.
Alexander W
AW
Tarr
Ania M
AM
Owsianka
Judith M
JM
Timms
C Patrick
CP
McClure
Richard J P
RJ
Brown
Timothy P
TP
Hickling
Thomas
T
Pietschmann
Ralf
R
Bartenschlager
Arvind H
AH
Patel
Jonathan K
JK
Ball
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000915:Antibody Affinity; D002460:Cell Line; D000939:Epitopes / Q000276:immunology*; D016174:Hepacivirus / Q000276:immunology*; D006526:Hepatitis C / Q000821:virology; D018937:Hepatitis C Antibodies / Q000276:immunology; D018936:Hepatitis C Antigens / Q000737:chemistry / Q000276:immunology; D006801:Humans; D009500:Neutralization Tests; D019151:Peptide Library; D011487:Protein Conformation; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000939:Epitopes; D018937:Hepatitis C Antibodies; D018936:Hepatitis C Antigens; D019151:Peptide Library; D014759:Viral Envelope Proteins; C091015:glycoprotein E2, Hepatitis C virus