Enhancement Of The Immunogenicity Of An Alphavirus Replicon-based DNA Vaccine Against Classical Swine Fever By Electroporation And Coadministration With A Plasmid Exressinorcine Interleukin2

There are several advantages of the alphavirus replicon-based DNA vaccine pSFV1CS-E2againstclassical swine fever, such as self-replication, high-biosafety, high-level expression and so on. However,it is difficult to deliver the DNA vaccine into cells, so efforts should be made to enhance itsimmunogenicity. Electroporation (EP) is a technology to introduce macromolecules such as nucleicacids into cells via the application of brief electric pulses to induce transient and reversiblepermeabilization of the cell membrane. Interleukin2(IL-2) has been extensively used as adjuvant forDNA vaccines, for it is able to upregulate the magnitude and duration of immune responses.In this study, EP and a plasmid expressing porcine IL-2were used to improve the immunogenicityof pSFV1CS-E2. Pigs were immunized with pSFV1CS-E2alone or together with IL-2by EP or bysimple intramuscular injection. The results showed that EP combined with IL-2resulted in markedenhancement of E2-specific antibody responses. Moreover, CSFV-specific lymphocyte proliferation,IFN-γ and IL-4secretions were increased significantly in the pSFV1CS-E2+IL-2/EP group. Pigsimmunized with pSFV1CS-E2plus IL-2by EP were completely protected from lethal challenge, whichis comparable to the sterilizing immunity and full protection offered by the live attenuated vaccineC-strain and in contrast with the incomplete protection conferred by pSFV1CS-E2without or with IL-2or EP alone, as demonstrated by the presence of pathological changes or viral loads. In addition, theanimals immunized with this DNA vaccine could be distinguished from infected animals. We concludethat EP in combination with IL-2can significantly improve the immunogenicity of pSFV1CS-E2, whichis a potential marker vaccine against CSF.