Characterization of the Env reactivity of serum antibodies elicited by EIAV
infection of horse 9807. Envelope-specific reactivities were analyzed in both an (A) end-point titer assay and a (B) neutralization assay. (A) Longitudinal characterization of the quantitative properties of induced EIAV envelope-specific antibodies were conducted in ConA ELISA assay utilizing EIAVPV as the antigen. Mean serum antibody titers for each time point are presented as the log10 of the highest reciprocal dilution yielding reactivity two standard deviations above background. (B) The mean reciprocal dilutions of serum from infected horses that neutralized 50% of input EIAVPV or EIAVPAgp90 as measured in an infectious center assay. Serum samples included: EIAVPA- serum from the original Pennsylvanian field isolate plasma donor and serum from the recipient pony #9807, EIAVPV- serum from an experimentally infected long-term inapparent carrier. The line (dashed black line) denotes the cut off (≥ 25) value for valid 50% neutralization titers. MPT, months post transfer; DPI, days post infection.