In-vitro and In-vivo Evaluations of a Developed Bivalent Sheep Pox and Peste des Petits Ruminants Vaccine

Peste des petits ruminants (PPR) and Sheep Pox (SP) are two significant viral diseases of small ruminants, responsible for substantial economic losses, particularly across Asia and Africa, including Egypt. PPR is induced by the PPR virus (PPRV), which is categorized under the Morbillivirus genus of the Paramyxoviridae family, The Sheep Pox virus (SPV) is classified under the Capripoxvirus genus, which is a member of the Poxviridae family This study evaluated the in vivo safety, in vitro quality, stability and sterility parameters of a new developed combined live-attenuated vaccine (MEVAC®) against PPR and SP. The PPR vaccine was based on the Nigeria 75/1 strain, while the Sheep Pox vaccine was developed from the Romanian strain. Safety assessments were performed in target species (sheep and goats) using both 1× and 10× field doses, confirming excellent safety profiles for both vaccines, with no adverse local or systemic reactions observed during the observation period. The PPR virus was propagated in Vero cell lines, while the SP virus was cultured in Ovine heart cell cultures. The PPR virus was harvested twice at about /nearly 50–60% and 80–90% cytopathic effect (CPE), while SPPV was harvested at nearly 80–90% CPE. The final viral titers per vaccine vial were recorded as 105.5 and 106.5 Tissue Culture Infective Dose fifty (TCID50), for PPRV and SPPV respectively. The vaccine successfully passed the vacuum test, confirming its physical integrity. The virus titers measured before and after lyophilization showed a reduction of approximately 100.1 TCID50). The sterility test revealed no microbial contamination, confirming that the product was sterile. Furthermore, the residual moisture (RM) content, a critical factor for vaccine stability, was measured at 1.9%, which falls below the acceptable limit of ≤3%. Overall, the bivalent live-attenuated vaccine demonstrated excellent safety, appropriate viral titration, and full compliance with quality control standards, supporting its suitability for field application in disease control programs.