Mechanisms of equine infectious anemia virus escape from neutralizing antibody responses define epitope specificity

Determining mechanisms of viral escape to particular epitopes recognized by virus-neutralizing antibody can facilitate characterization of host-neutralizing antibody responses as type- versus group-specific, and provides necessary information for vaccine development. Our study reveals that a single N-glycan located in the 5′ region of the Wyoming wild-type equine infectious anemia virus (EIAV) principal neutralizing domain (PND) accounts for the differences in neutralization phenotype observed between PND variants, while variations in charged amino acids within the PND do not appear to play a key role in viral escape. Site-directed mutagenesis and peptide mapping of a conserved epitope to neutralizing antibody in the 3′ region of the PND showed rapid selective pressure for acquisition of a 5′ PND N-glycan responsible for defining the specificity of the neutralizing-antibody response.