Peste des petits ruminants virus (PPRV), which is the only member of the Morbillivirus caprinae species and belongs to the genus Morbillivirus within the Paramyxoviridae family, causes the highly contagious viral sickness “Peste des petits ruminants (PPR).” PPR is of serious economic significance for small ruminant production, particularly in Africa. Control of this critical disease depends highly on successful vaccination against the PPRV. An in-depth understanding of the genetic evolution of the live-attenuated PPR vaccine Nigeria 75/1 strain used in Africa is essential for the successful eradication of this disease by 2030. Therefore, this study investigated the possible genetic evolution of the PPR vaccine produced by various African laboratories compared with the master seed available at AU-PANVAC. RT-PCR was performed to amplify a segment of the hypervariable C-terminal part of the nucleoprotein (N) from commercial batches of PPR vaccine Nigeria 75/1 strain. The sequences were analyzed, and 100% nucleotide sequence identity was observed between the master seed and vaccines produced. The results of this study indicate the genetic stability of the PPR vaccine from the Nigeria 75/1 strain over decades and that the vaccine production process used by different manufacturers did not contribute to the emergence of mutations in the vaccine strain.

Peste des Petits Ruminants (PPR) disease is widely distributed in Africa. Live attenuated PPR vaccines are produced using approved Nigeria 75/1 and Sungri/96 strains by the World Organisation of Animal Health (WOAH) to control the disease. These PPR vaccines are very efficacious; however, the main challenge is the maintaining of the cold chain during vaccine distribution and delivery. This study evaluated the thermotolerance of freeze-dried and reconstituted PPR Nigeria 75/1 vaccines from vaccine manufacturers using eight stabilizer formulations (lactalbumin hydrolysate and sucrose, sucrose and peptone, Weybridge medium, trehalose, Lactose and N-Z Amine, lactalbumin hydrolysate, sucrose and L glutamine, skimmed milk, and lactalbumin hydrolysate, maltose and gelatine). Aliquots of the reconstituted PPR vaccine batches were titrated after 2, 4, and 6 h of storage at 4 °C and 40 °C. The PPR vaccines were also titrated after storage at 40 °C and 45 °C for 3 and 5 days. The results showed that reconstituted PPR vaccine stabilized with lactalbumin hydrolysate–sucrose promoted tolerance at 40 °C for 6 h. It was also noted that all reconstituted PPR vaccine formulations except the formulation stabilized with lactalbumin hydrolysate–maltose–gelatine maintained the titre above a 10^2.5 TCID₅₀/dose after 4 h of storage at 4 °C. Furthermore, the results showed that the PPR vaccine formulation containing lactalbumin hydrolysate sucrose was as the only one that maintained the titres above 10^2.5 TCID₅₀/dose after storage at 45 °C for 5 days, with a titre loss of 10^0.95 TCID₅₀/dose. Therefore, vaccine manufacturers producing PPR vaccines for use in tropical field regions could preferably use lactalbumin hydrolysate–sucrose stabilizer in vaccine formulation.