Fv structure of monoclonal antibody II-481 against herpes simplex virus Fc gamma-binding glycoprotein gE contains immunodominant complementarity determining region epitopes that react with human immunoglobulin M rheumatoid factors.
Human immunoglobulin M (IgM) rheumatoid factors (RFs) show primary direct enzyme-linked immunosorbent assay (ELISA) reactivity with Fab rather than Fc fragments of monoclonal antibody (mAb) II-481 directed against the Fc gamma-binding site of herpes simplex virus glycoprotein gE. This preferential anti-Fab specificity suggests that RFs react with antigen-binding portions of mAb II-481 as anti-idiotypic antibodies directed at the combining site regions of mAb reacting with the Fc gamma-binding region of gE. Analysis of this idiotype-anti-idiotype reaction employed polymerase chain reaction amplification and sequencing of the variable heavy and light (VH and VL) regions of mAb II-481. When VH and VL regions of mAb II-481 were synthesized as overlapping 7-mer peptides on polypropylene pins, a panel of 10 polyclonal and 6 monoclonal human IgM RFs reacted primarily with epitopes within the three solvent-exposed mAb II-481 complementarity determining regions (CDRs). Preincubation of single CDR heptamer peptides with IgM RFs in free solution, resulted in 63-100% inhibition of RF binding to mAb II-481 on the ELISA plate, confirming the antigenic importance of linear CDR regions for RF reactivity. Combinations of two or three CDR peptides frequently produced 94-100% inhibition of RF binding to whole mAb II-481. Control peptides, singly or in combination, showed no inhibition. Computer modeling suggested that the RF-reactive mAb II-481 Fv region and a previously demonstrated RF-reactive CH3 epitope displayed considerable three-dimensional similarities in conformation. These studies may provide insight into limited shape homologies possibly involved in an RF anti-idiotypic reaction.
Department of Medicine, University of Florida School of Medicine, Gainesville 32610.
P J
PJ
Johansson
C
C
Malone
W
W
Swietnicki
B M
BM
Dunn
R C
RC
Williams
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D001483:Base Sequence; D003198:Computer Simulation; D016056:Immunodominant Epitopes; D007128:Immunoglobulin Fragments / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D007074:Immunoglobulin G / Q000378:metabolism*; D007075:Immunoglobulin M / Q000276:immunology*; D007135:Immunoglobulin Variable Region / Q000276:immunology; D051379:Mice; D008969:Molecular Sequence Data; D011487:Protein Conformation; D012217:Rheumatoid Factor / Q000276:immunology*; D014759:Viral Envelope Proteins / Q000276:immunology* / Q000378:metabolism
D000911:Antibodies, Monoclonal; D016056:Immunodominant Epitopes; D007128:Immunoglobulin Fragments; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007135:Immunoglobulin Variable Region; D014759:Viral Envelope Proteins; C044768:glycoprotein E, herpes simplex virus type 1; C055966:immunoglobulin Fv; D012217:Rheumatoid Factor