Experimental production and immunogenicity evaluation of an inactivated Peste des Petits Ruminunts candidate vaccine in sheep and goat

Peste des Petits Ruminunts (PPR) is an acute and contagious viral disease with rapid infection and transmission in sheep and goats. Vaccination of livestock is the best solution to prevent the spread and control of the disease. The aim of this study was to evaluate the immune response derived from vaccination with six formulations of inactivated PPR vaccine in goats and sheep using a completely randomized design with 2 × 2 factorial arrangement. The attenuated PPR virus was amplified in a highly manipulated suspension lymphoid cell having a high passage potential, and then inactivated using two inactivators (4 mM bromoethylene imine [BEI] or 3% hydrogen peroxide [H2O2]). Thereafter each inactivated virus was formulated using three different helpers (aluminum hydroxide, aluminum phosphate, and a 50% mixture of each of these two adjuvants). Iimmunogenicity and safety of the formulated candidate vaccines were evaluated by respective two doses of 0.1 and 1 (10-fold doses) ml of the vaccines administrated into 38 sheep and 28 goats. Each dose was subcutaneously administrated on 0 and 21 days of the experiment and post vaccination sera antibody titer against PPR virus was measured on days 0, 14, 21, 35, 42 and 60. The results showed that the mean antibody titer against PPR virus was not influenced neither by inactivator nor adjuvant up to 21- and 60-days post vaccination (P> 0.05). Also, no significant interaction was observed between different inactivators and adjuvants (P> 0.05). The appropriate antibody titers observed in different experimental groups indicated a good immunization of the formulated vaccines; however, their efficacy remained to be investigated using challenge test. Also, due to the lack of carcinogenicity, cheapness and environmental compatibility reported for H2O2, it is nominated as an inactivator in production inactivated PPR vaccine.