Figure 1.

Establishment of a pig model for CSFV infection in vivo. Ten healthy 2-month-old pigs with CSFV and CSFV antibody negative were randomly divided into two groups: a mock group and a CSFV infection group. About 1 × 10⁵ TCID₅₀/ml viral stock was intramuscularly injected into bilateral neck of pigs for CSFV infection, and pigs in the mock group were only injected the same volume of PBS. Body temperature was measured everyday till to 7 dpi (A), and clinical symptoms of the experimental pigs were observed and recorded daily for calculation of CS values (B). All the experimental pigs were sacrificed at 7 dpi for samples collections, and three pigs from each group were randomly selected for the following tests and analyses. (C) For further confirmation of CSFV infection, E2 structural genes in the collected immune organs (tonsil, thymus, spleen and inguinal lymph node) were detected by RT-PCR. The expected product (241 bp) was identified by 1% agarose gel electrophoresis. (D) Simultaneously, expression of E2 proteins in these organs were analyzed by IHC method exploiting a mouse anti-E2 monoclonal antibodies. Pictures were captured with a NIKON Eclipse Ci biological microscope (Japan) under a magnification of 200×. The appreciable brown staining is considered as positive expression of E2 proteins. Bar, 100 μm.