FIG. 3.

Development of NA in cats infected with selected FIV isolates. Groups of two SPF cats were infected with isolates obtained from animals with broadly (left panels) or poorly (right panels) cross-reactive NA. At the times indicated, injected cats were examined for anti-FIV enzyme-linked immunosorbent assay (ELISA) antibodies with gradient-purified, disrupted whole M2 virus as the antigen (▪) and for NA antibodies to the homologous virus (open columns) and to selected heterologous isolates (filled columns: ▤, M2; ▪, M17; ░⃞, M26; ▨, M45; ▧, M92); cross-reactive NA to M73 tested constantly negative.