Antigenicity of rabies virus glycoprotein

Abstract

Although the number of antigenic sites on the rabies virus glycoprotein that have been described regularly increases with time, no attempt has been made to carefully evaluate the relative importance of each of these sites. Here we provide a more precise description of the antigenicity of the protein in mice of the H-2d haplotype; we developed this description by using 264 newly isolated monoclonal antibodies (MAbs) and a collection of neutralization-resistant (MAR) mutants. Most of the MAbs (97%) recognized antigenic sites previously described as II and III. One minor antigenic site separated from site III by three amino acids, including a proline, was identified (minor site a). Despite their proximity, there is no overlap between site III and minor site a; i.e., site III-specific MAR mutants were neutralized by the six MAbs defining minor site a, and vice versa. One of our MAbs, 1D1, reacted with sodium dodecyl sulfate-treated glycoprotein in Western blots (immunoblots) under reducing conditions and was therefore probably directed against a linear epitope, A MAR mutant selected with this MAb was still neutralized by MAbs of other specificities. This linear epitope was called G1 (G, Gif). As a general rule, we propose to reserve the term "antigenic site" (either major or minor) for regions of the protein which are defined by several MAbs originating from different fusions and to describe regions of the protein which are defined by a single MAb as epitopes. It would be interesting to test whether the same regions of the rabies virus glycoprotein are antigenic in mice of different haplotypes or in other species.

Mutations Conferring Resistance to Neutralization by a Soluble Form of the Neurotrophin Receptor (p75NTR) Map outside of the Known Antigenic Sites of the Rabies Virus Glycoprotein

“…Furthermore, a nucleotide transversion (T3G), believed to be less frequent than transition events, was independently found twice. The number (4) of srr mutations was similar to the number of mutants selected for their resistance to the neutralization by a single MAb (6,28,43,49) (Fig. 7).…”

“…The abscissa shows the number of different amino acid substitutions found at each amino acid position. Most of the mutations have already been described previously (6,28,43,44,49,59), with the exception of the mutations at positions 203, 210 in site II, 331 in site III, and 342 and 354 in minor site a (F. Lafay It is noteworthy that the K330NϩR333M mutant, resulting from two independent mutational events (12), could not have been selected on CVS stocks in this selection process. The role of p75NTR in RV infection is still unknown, and some previous reports need to be reevaluated in the light of recent data.…”

“…Our group has selected about 50 RVG mutants from the challenge virus strain (CVS) that are resistant to neutralization by anti-RVG MAbs. Several independent antigenic sites have been defined, depending on their interaction with neutralizing anti-RVG MAbs and on the effect of mutations (6,29). Site II is the major antigenic site (70% of the MAbs recognize this region).…”

“…Site III is a conformational site (amino acids 330 to 340) and plays a major role in RV propagation in the nervous system and pathogenicity (12,16,49,59). Two minor sites (site a at amino acids 342 and 343 [6] and a linear site at amino acids 251 to 264 [14,28,60]) and several other epitopes have also been described (28). RVG can adopt at least two conformations (20): N (for neutral) and I (for fusion inactive).…”

Studies on the Escape Mutants of Rabies Virus Which Are Resistant to Neutralization by a Highly Conserved Conformational Epitope‐Specific Monoclonal Antibody #1‐46‐12

“…Monoclonal antibodies (mAbs) have been very useful tool for studying the relationships between the molecular structures and functions of proteins. Using many mAbs, epitopes of the rabies virus G protein have been studied for years, and at least three major antigenic sites (I, II and III) have been identified on the ectodomain of the G protein (3,6,15). One of the major epitopes studied so far is the highly conserved antigenic site III which is recognized by a virus-neutralizing mAb #194-2, and extensive studies with the escape mutants demonstrated that an amino acid substitution in the epitope site (e.g., Arg-333 to Gln) affected the neurovirulent nature of the virus (5,26).…”