The immunopotentiator CVC1302 enhances immune efficacy and protective ability of foot-and-mouth disease virus vaccine in pigs

The immunological enhancement characteristics of the immunopotentiator CVC1302 were evaluated for foot-and-mouth disease virus (FMDV) inactivated vaccine in pigs. Eight-week-old piglets were vaccinated with the foot-and-mouth disease (FMD) vaccine alone (FMD-vaccine group) or with the addition of CVC1302 (FMD-CVC1302 group), and the serum liquid phase blocking ELISA (LPB-ELISA) antibody titers, IgG1 and IgG2 levels, and the levels of four cytokines secreted by peripheral blood lymphocytes were measured at 28 days post vaccination (dpv). In the FMD-CVC1302 group, the LPB-ELISA antibody titers, IgG1, and IgG2 titers, and IL-2, IL-4, IL-6, and IFN-gamma levels at 28 dpv were significantly higher than those in the FMD-vaccine group. The FMD-CVC1302 group had long-lasting antibody titers (>7.8 log(2)), lasting for at least 6 months. In addition, piglets were vaccinated with or without addition of CVC1302 to the FMD vaccine at three different doses (1, 1/3, and 1/9 of the standard vaccine dose) and the serum LPBELISA antibody and serum neutralizing (SN) antibody titers were detected at 28 dpv. Then all pigs were challenged with virulent FMDV for PD50 value, and the levels of FMDV-specific RNA copies for the two full-dose groups at 3 and 10 days post challenge (dpc) were measured. The LPB-ELISA and SN antibody titers for the three doses in the FMD-CVC1302 groups were significantly higher than those in the FMD-vaccine groups at the same doses (p < 0.05). Post-virus challenge, the FMDV-specific RNA copy number in the FMD-CVC1302 group was lower than that in the FMD-vaccine group at 3 and 10 dpc. The PD50 value was 15.85 for the FMD-CVC1302 group, which was obviously higher than that for the FMD-vaccine group (10.96), and in the 1/9-dose of FMD-vaccine group only 3/5 pigs were protected. These results indicate that CVC1302 can enhance the immune efficacy and protective ability of the FMD vaccine in pigs. (C) 2018 Elsevier Ltd. All rights reserved.