Improved humoral immune response of oil adjuvant vaccine by saponin co-adjuvantation against haemorrhagic septicaemia in mice and buffalo calves

Abstract

Oil adjuvant vaccine (OAV) formulations, viz. OAV (OAV without saponin) and S-OAV (OAV with 420 µg saponin/ml) were prepared against haemorrhagic septicaemia using Pasteurella multocida, P52 antigen. Three groups of mice, each group with 40 mice, were inoculated with respective OAV, S-OAV and sterile phosphate buffer saline and monitored the ELISA antibody titer for 45 days. In another experiment, 2 groups of buffalo calves, each group with 3 calves, were vaccinated with OAV and S-OAV and monitored the ELISA antibody titer for 4.5 months. Viscosity of OAV was 222.28 and of S-OAV 215.10 centipoise. The anti-P. multocida specific serum ELISA antibody titers were significantly higher in S-OAV on 14th days post vaccination compared to OAV and control and remained consistently higher during the experiment. Fluorescent activated cell sorter study revealed that CD4 T cells were significantly higher in S-OAV group as compared to OAV and control, while CD8 T cells was 28.83% higher than control. All vaccinated groups were 100% protected after direct intraperitoneal challenge with 100 LD50 of live P. multocida, serotype B, strain P52 on 45th DPV. However, after challenge with 1000 LD50 the S-OAV group had 80% protection as compared to 60% protection by OAV. Trial on buffalo calves further confirmed the finding of mice model as higher ELISA antibody titers were observed by S-OAV group as compared to OAV throughout the experiment period since seventh DPV onwards. Thus, saponin coadjuvantation of OAV increased the CD4, CD8 T cells population, improved the humoral immune response and protection.