Figure 4

Murine T-cell responses elicited by immunization with the oral porcine circovirus type 2 (PCV2) vaccine. The horizontal and vertical axes denote the fluorescence intensity (CFSE) and the number of acquired events, respectively. The CD4⁺(A) and CD8⁺(B) T-cell populations in the spleens of non-immunized mice (right panels) and in the spleens of mice immunized with the chitosan encapsulated vaccine (left panels). Splenocytes were harvested 8 weeks after primary immunization and re-stimulated in vitro with PK15-derived PCV2 virions. The cells exposed to PCV2 virions are shown in light red and those not exposed to PCV2 virions are shown in purple (vehicle). As a positive control for non-specific lymphocytic proliferation, splenocytes were incubated in 96-well plates coated with anti-CD3 antibodies (grey histograms). The results show representative histograms from two independent experiments.