FIG. 2.

Titers of anti-FIV ELISA antibody in vaccinated cats at different time points postimmunization. Sera were tested against FIV-M2 antigen (●) and FIV-Pet antigen (■). The results are expressed as the reciprocal of the highest serum dilution that produced optical density readings higher than the average value obtained with 20 control FIV-negative sera plus three times the standard deviation. Sera that proved unreactive at a 1:100 dilution, the lowest dilution tested, are indicated as having titers of <100. Arrows indicate the times that vaccine boosters were administered to all cats.