PPR is an acute highly contagious viral disease of small ruminants which is endemic in Pakistan. Present study was aimed to evaluate the freeze dried PPRV vaccine with variable biological titer to induce protective immune response in beetal goats. The comparative immune response of animals to adjuvant and non-adjuvant vaccine and duration of immunity was also studied. Effect of boosting on the humoral immune response of animals as well as shelf life of various vaccines was also evaluated. Each of the vaccines was inoculated in a group of five animals. Serum samples were collected at specified time intervals and antibody levels were detected through cELISA as PI values and neutralization test as MNA titer.
The virus was propagated on the Vero cells. It was estimated that infecting 2 x 107cells with 104.00 TCID50 virus concentrations added to a T-175 cell culture flask at the time of subculture yielded maximum virus titer in the cell culture harvest following three freeze thaw cycles of the contents. The freeze dried vaccine with a biological titer of 105.00 TCID50 per dose provoked maximum antibody titer followed by the ones with a titer of 104.00 or 103.00TCID50 which provoked nearly equivalent protective immune response while the animals inoculated with a vaccine having 102.00 TCID50virus concentrations developed minimum antibody titer. The oil adjuvant PPRV vaccines elicited significantly higher antibody titer in comparison to gel based vaccines but however minimum antibody titers were detectable in response to freeze dried vaccines. Although protective antibody level (? 10 neutralizing antibody units) was detectable in the animals vaccinated with either oil based, gel based or freeze dried vaccine containing biological titer of 104.00 TCID50 but however the extent and duration of immunity was found to be most superior in response to oil based vaccines. It can be concluded that a single shot of either gel or oil based vaccine can provide protection in the vaccinated animals for a minimum of one year duration. Goats receiving a booster dose of the vaccines had a significantly higher antibody tier in comparison to the ones who received single dose of the vaccines. The freeze dried and wet vaccine kept at 4 °C did not show any significant drop in the biological activity of the virus even after 12 months of storage. Immunogenicity of the both adjuvant and non-adjuvant vaccines, as measured through the immune response in the vaccinated animals, also remained unaffected after 12 months of storage at 4 °C.