A Promising Trigene Recombinant Human Adenovirus Vaccine Against Classical Swine Fever Virus.

Classical swine fever (CSF) vaccine based on HAdV-5 had achieved an efficient protection in swine. Both classical swine fever virus (CSFV) E0 glycoprotein and E2 glycoprotein were the targets for neutralizing antibodies and related to immune protection against CSF. Interleukin-2 (IL2), as an adjuvant, also had been used in CSF vaccine research. In this study, coexpression of the CSFV E0, E2, and IL2 genes by HAdV-5 (rAdV-E0-E2-IL2) was constructed and immunized to evaluate its efficacy. Three expressed genes had been sequentially connected with foot-and-mouth disease virus 2A (FMDV 2A). The vaccine was administered by intramuscular inoculation to CSFV-free pigs (10(8) TCID50) twice at triweekly intervals. No adverse clinical signs were observed in any of the pigs after vaccination. The vaccine induced strong humoral and cellular responses that led to complete protection against clinical signs of lethal CSFV infection, viremia, and shedding of challenge virus. The rAdV-E0-E2-IL2 is a promising, efficient, and safe marker vaccine candidate against CSFV.