Abstract
Vaccination is the most effective means of preventing Peste-des-petits-ruminants (PPR), an important disease of small ruminant population. The thermolabile nature of PPR vaccine poses a major constraint in shipping, storage and its successful application. In view of limited thermotolerance of PPR virus and ongoing global PPR control and eradication program, development of a thermotolerant PPR vaccine was tried using a novel lyophilization protocol and improved thermostabilization. A lyophilization cycle of 16 h (h) using 200 µl of PPR vaccine virus (stock titre 5.8 log10 TCID50/vial in 200 µl) was developed. For this, five stabilizer formulations were selected out of ten formulations based on the stability of liquid vaccine at 37 °C and three freeze-thaw cycles. Improved thermostabilization of PPR vaccines was obtained by inclusion of 5% trehalose and 0.5% gelatine to Lactalbumin hydrolysate-sucrose (LS) formulations which significantly improved the stability of lyophilized vaccines with a shelf-life of at least 1305.3 days at 2-8 °C, 23.68 days at 25 °C, 20.88 days at 37 °C, 5.01 days at 40 °C and 3.22 days at 45 °C which qualifies the standards of a thermotolerant PPR vaccine as defined by the FAO and OIE. In reconstituted vaccines, the combination of LS, trehalose and gelatin (LSTG) provided a shelf-life of 1.77 days at 37 °C, 22.41 h at 40 °C and 10.05 h at 45 °C. The study suggested that use of the short lyophilization protocol standardized with 200 µl of lyophilized PPR vaccine stabilized with LSTG formulation, can be used to develop and upscale thermotolerant PPR vaccines during national and global PPR control and eradication as targeted by the FAO and OIE by 2030.