The study was conducted to find out a way that might lead to potentiation of both cryostability and thermostability criteria of the live attenuated PPR virus Nigerian75/1 vaccine. This vaccine as with other Morbillivirus vaccines is thermolabile; i.e. thermal degradation occurs on exposure to inconvenient temperatures, even though if kept in a lyophilized state. This draw-back poses difficulties when launching vaccination campaigns especially in arid and semi arid areas if a cold chain necessity is logistically unavailable to maintain good vaccine titers until delivery of the product to targeted animals. A recently advocated stabilizer formulation (Tris/ Trehalose) was tested for its cryoprotectant as well as thermo- resistant potentialities on being thoroughly incorporated into the PPRV-suspension just prior to lyophilization process and under varying storage temperature conditions, in comparison to the conventionally used Weybridge medium (WBM). It was found that the Tris/ Tre formula was far superior to the WBM one since the loss in virus titre was 0.1 and 0.4 log10 TCID50 /ml for Tris/ Tre and WBM stabilized vaccines respectively during the lyophilization process. The results preferred the choice of Tris/Tre Stabilizer formula on viability of 75/1 PPR virus during lyophilization process and preservation at -20◦C and -70◦C. Tris/Tre stabilized vaccines stored at 4◦C and -4◦C for 9,12 months respectively maintained sufficient viable PPR virus to protect goats. Even at a drastic high temperature (37°C and 45°C), the Tris/Tre formula could conserve satisfactory vaccine titre after 5 and 2 days of exposure, corresponding to only 1.5 and 1 day with the WBM formula, respectively. In conclusion, Tris/Tre stabilized PPRV- attenuated vaccine, enhanced to a reasonable extent both cryoprotectant and thermotolerence potentialities as compared to the WBM one and it is superior to WBM in inducing protective immune response after vaccination in tested goats.
Key words: Peste des Petits Ruminants, Stabilizer, Tris/Trehalose (Tris/Tre), Weybridge medium (WBM), Goats.
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