Fig. 2

The CSF-E2 subunit vaccine could prevent CSFV horizontal transmission on a vaccination–challenge animal trial. SPF pigs were immunized with CSF-E2 subunit vaccine (group A, circle and black line) or placebo (group C, square and light gray dashed line) and challenged with CSFV ALD strain (1 × 10⁵ TCID₅₀) after two vaccinations. Groups A and C were raised in two isolated ABSL-2 units. The sentinel SPF pigs (group B, triangle and gray line) were cohabited with group A at 4 days after the virus challenge to monitor the transmission of CSFV. Pigs in group C were sacrificed 7 days after the virus challenge due to severe clinical symptoms. a The CSFV-specific neutralizing antibody level was analyzed after the CSFV challenge. The gray dotted line indicated the protective neutralizing antibody level (1:32). b The viremia level was monitored after the virus challenge to identify the infection of CSFV. c and d The number of leukocytes and platelets were counted after virus challenge to monitor CSFV infection-induced leukopenia (< 11,000 cells/μL, gray dotted line) and thrombocytopenia (< 211,000 cells/μL, gray dotted line)