Abstract:

To explore the immunity efficacy of a Chimeric Porcine Circovirus (PCV1-2) to piglets, the protective immunity induced by the PCV1-2 against porcine Circovirus type 2 (PCV2) infection in piglets were investigated. A total of 10 healthy conventional piglets were randomly and equally assigned to two groups of 5 piglets each. Piglets in group 1 were vaccinated by intramuscular injection with 106.05 50% tissue culture infective doses (TCID50) of the Chimeric PCV1-2 live virus. Piglets in group 2 were not vaccinated and served as controls. By 28 days post-vaccination (DPV), all piglets had seroconverted to PCV2 ORF2 antibody. At 28 DPV, all piglets were challenged orally and intranasally with 5?106.25 TCID50 wild pathogenic PCV2 viruses. All vaccinated piglets remained clinically healthy after challenge, while unvaccinated animals developed clinical signs relative to PCV2 diseases. The PCV2 DNA loads in sera and lymphoid tissues were significantly (P<0.05) reduced in vaccinated piglets. Moderate-to severe lymphoid depletion and histiocytic replacement were detected in most lymphoid tissues of unvaccinated piglets but none in vaccinated piglets. These data indicated that the Chimeric PCV1-2 induced protective immunity against PCV2 infection and could potentially serve as an attenuated PCV2 vaccine candidate.