Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)

First Advisor

Charles J. Issel


Monoclonal antibodies (MCAbs) produced against the prototype cell-adapted Wyoming strain of equine infectious anemia virus (EIAV), a lentivirus, were studied for reactivity with the homologous prototype and 16 heterologous isolates. Eighteen hybridomas producing MCAbs were isolated. Western blot (immunoblot) analyses indicated that 10 were specific for the major envelope glycoprotein (gp90) and 8 for the transmembrane glycoprotein (gp45). Four MCAbs specific to epitopes of gp90 neutralized prototype EIAV infectivity. These neutralizing MCAbs apparently reacted with variable regions of the envelope gp90, as evidenced by their unique reactivity with the panel of isolates, suggesting recognition of at least three different neutralization epitopes. The conformation of these epitopes appears to be continuous, as they resisted treatment with sodium dodecyl sulfate and reducing reagents. Monoclonal antibodies that reacted with conserved epitopes on gp90 or gp45 failed to neutralize EIAV. Our data also demonstrated that there was a large spectrum of possible EIAV serotypes and confirmed that antigenic variation occurs with high frequency in EIAV. Moreover, variation is a rapid and random process, as no pattern of variant evolution was evident by comparison of 13 isolates from parallel infections. Monoclonal antibodies were used to dissect the antigenic sites of the surface glycoproteins of the prototype cell-adapted Wyoming strain of EIAV. Serologic reactivities of these MCAbs were determined by ELISA, additive ELISA, competitive ELISA, and Western blot assays. Antigenic reactivity of gp90 was localized on at least four distinct epitopes, two of which were important in neutralization. Our studies also revealed that these epitopes were localized on overlapping antigenic sites on gp90. Only two distinct non-overlapping epitopes were identified on gp45. Competitive binding studies of neutralizing MCAbs and reference EIA-positive horse serum delineated the presence of a neutralization domain on gp90 that appears to be immunodominant both in naturally infected horses and in mice immunized with EIAV. Limited proteolytic fragmentation of the gp90 component of several serologically distinct EIAV isolates produced common 12K immunoreactive fragments that contained a conserved epitope. The conserved antigenic regions on EIAV glycoproteins as well as a neutralization domain on gp90, which can be used as potential targets for vaccine development. (Abstract shortened with permission of author.).