Evaluation of a Combined Peste des Petits Ruminants and Rift Valley Fever LiveVaccine in Sheep and Goats

Small Ruminants (SR) are an important source of nutrition and economies for sustaining the livelihoods of vulnerable human population in many rural regions of Africa. The health of these animals continues to be threatened by the highly infectious trans boundary viral diseases, such as Peste des Petit Ruminants (PPR) and Rift Valley fever (RVF) as well as other infectious diseases that cause high rates of disease and death in these animals. Therefore, the objective of this study was to develop and evaluate a combined vaccine for PPR and RVF in sheep and goats in Morocco. The vaccine was prepared by propagating the viruses together in Vero cells and the selection of different infectious doses for conducting vaccine trials in the animals. Safety was assessed based on rectal temperature, clinical manifestations and possible adverse reaction at the vaccine injection site. Immunogenicity was determined by testing sera samples obtained Post-Vaccination (PV) for PPRV and RVFV ELISA IgG and serum neutralizing antibodies. The results indicated that the vaccine was safe and immunogenic in the animals with minimal auto-interference between the 2 viruses. Sheep vaccinated with different doses of the combined PPRV/RVFV vaccine developed detectable PPRV antibody by day 7 pv, including 80% of the groups of animals that received the same doses and 100% that received a low and high dose. In the goats that received the combined PPRV/RVFV, RVFV antibody was detected in all vaccinated animals at day 7 pv, including 70% of the animals that received the low dose, 100% that received the high dose and 20% of the animals that received the same dose. Our finding revealed that the combined live PPRV/RVFV vaccine can be used safely as a one dose vaccination in sheep and goat for large vaccination campaign to prevent both PPRV and RVFV diseases in enzootic countries.