FIG. 2.

FIV-M2-specific cell proliferation by PBMCs after the start of immunization. PBMCs from cats of the vaccine group (white columns) or the mock group (black columns) were tested for FIV-M2-specific proliferation at different months after the initiation of immunization. Proliferation is expressed as S.I., which is calculated as the ratio of radioactivity incorporated in the presence and in the absence of antigen. The time of challenge corresponds to month 7; month 5 corresponds to the time of the booster.