Characterization of epitopes on the rabies virus glycoprotein by selection and analysis of escape mutants

• Published in: Virus research 2016-07, Vol.220, p.161-171
• Main Authors: Fallahi, Firouzeh, Wandeler, Alexander I., Nadin-Davis, Susan A.
• Format: Article
• Language: English
• Subjects: Amino Acid Substitution; Animals; Antibodies, Monoclonal - metabolism; Antibodies, Neutralizing - metabolism; Antibodies, Viral - metabolism; Antigen-Antibody Complex - chemistry; Antigens, Viral - chemistry; Antigens, Viral - genetics; Antigens, Viral - immunology; Epitope Mapping; Epitopes - chemistry; Epitopes - genetics; Epitopes - immunology; Female; Gene Expression; Glycoproteins - chemistry; Glycoproteins - genetics; Glycoproteins - immunology; Immune Evasion - genetics; Lyssavirus; Mice; Mutation; Neutralization Tests; Rabies - pathology; Rabies - virology; Rabies virus; Rabies virus - genetics; Rabies virus - immunology; Rabies virus - pathogenicity; Sequence Analysis, RNA; Viral Envelope Proteins - chemistry; Viral Envelope Proteins - genetics; Viral Envelope Proteins - immunology
• ISSN: 0168-1702; 1872-7492
• DOI: 10.1016/j.virusres.2016.04.019

•Provides knowledge of the relationship of epitopes within two major antigenic sites of the rabies virus glycoprotein.•Several escape mutants were isolated using different monoclonal antibodies. For unknown reasons isolation of neutralization resistant mutants from ERA and two from WSKV were more feasible compared to BBBV or SHBV.•Overall, this study further clarifies the relationship between the different epitopes of antigenic sites I and III of the rabies virus G protein.•Such information adds to our knowledge of the antigenic properties of this protein and is of value during consideration of the design of anti-rabies antibodies to be used for provision of passive immunity during post exposure prophylaxis (PEP). The glycoprotein (G) is the only surface protein of the lyssavirus particle and the only viral product known to be capable of eliciting the production of neutralizing antibodies. In this study, the isolation of escape mutants resistant to monoclonal antibody (Mab) neutralization was attempted by a selection strategy employing four distinct rabies virus strains: the extensively passaged Evelyn Rokitnicki Abelseth (ERA) strain and three field isolates representing two bat-associated variants and the Western Canada skunk variant (WSKV). No escape mutants were generated from either of the bat-associated viral variants but two neutralization mutants were derived from the WSKV isolate. Seven independent ERA mutants were recovered using Mabs directed against antigenic sites I (four mutants) and IIIa (three mutants) of the glycoprotein. The cross-neutralization patterns of these viral mutants were used to determine the precise location and nature of the G protein epitopes recognized by these Mabs. Nucleotide sequencing of the G gene indicated that those mutants derived using Mabs directed to antigenic site (AS) III all contained amino acid substitutions in this site. However, of the four mutants selected with AS I Mabs, two bore mutations within AS I as expected while the remaining two carried mutations in AS II. WSKV mutants exhibited mutations at the sites appropriate for the Mabs used in their selection. All ERA mutant preparations were more cytopathogenic than the parental virus when propagated in cell culture; when in vivo pathogenicity in mice was examined, three of these mutants exhibited reduced pathogenicity while the remaining four mutants exhibited comparable pathogenic properties to those of the parent virus.