1.Evaluation of Efficacy of Stabilizers on the Thermostability of Live Attenuated Thermo-adapted Peste des petits ruminants Vaccines
Riyesh Thachamvally ; Balamurugan Vinayagamurthy ; Sen Amab ; Bhanuprakash Veerakyathappa ; Venkatesan Gnanavel ; Yadav Vinita ; Singh Kumar Raj
Virologica Sinica 2011;26(5):324-337
In this study,thermo-adapted(Ta)PPR vaccines were assessed for their stability at 25,37,40,42 and 45℃ in lyophilized form using two extrinsic stabilizers(lactalbumin hydrolysate-sucrose(LS)and stabilizer E)and in reconstituted form with the diluents(1 mol/L MgS04 or 0.85% NaCl). The lyophilized vaccines showed an expiry period of 24-26 days at 25℃,7-8 days at 37℃ and 3-4 days at 40℃. LS stabilizer was superior at 42℃ with a shelf-life of 44 h,whereas in stabilizer E,a 40 h shelf-life with a comparable half-life was observed. At 45℃,the half-life in stabilizer E was better than LS and lasted for 1 day. Furthermore,the reconstituted vaccine maintained the titre for 48 h both at 4℃ and 25℃ and for 24-30 h at 37℃. As both the stabilizers performed equally well with regard to shelf-life and half-life,the present study suggests LS as stabilizer as a choice for lyophilization with 0.85% NaCI diluent,because it has better performance at higher temperature. These Ta vaccines can be used as alternatives to existing vaccines for the control of the disease in tropical countries as they are effective in avoiding vaccination failure due to the breakdown in cold-chain maintenance,as this vaccine is considerably more stable at ambient temperatures.
2.A Rapid and Sensitive One Step-SYBR Green Based Semi Quantitative Real Time RT-PCR for the Detection of peste des petits ruminants Virus in the Clinical Samples
Balamurugan Vinayagamurthy ; Sen Arnab ; Venkatesan Gnanavel ; Yadav Vinita ; Bhanot Vandna ; Bhanuprakash Veerakyathappa ; Singh Kumar Raj
Virologica Sinica 2012;27(1):1-9
A sensitive and rapid single step real time (rt) RT-PCR was standardized using one-step Brilliant SYBR Green kit(R) for detection and semi-quantitation of peste des petitis ruminants virus (PPRV) using the virus RNA and matrix (M) protein gene-specific primers and compared with established conventional RT-PCR and TaqMan RT-PCR.The assay amplifies a 124 bp fragment of the PPRV M gene with Tm of 78.28 to 78.50.The assay was linear within a range of 50 ng to 0.5 fg total virus RNA with a detection limit (sensitivity) of 0.5 fg.Based on the serial dilution of the live-attenuated PPR vaccine virus,the detection limit was ~0.0001 cell culture infectious dose 50% units (TCID50).Additionally,swab materials spiked with known titre of vaccine virus were equally well detected in the assay.The standardized rt RT-PCR was easily employed for the detection of PPRV nucleic acid directly in the field and experimental clinical samples.The assay detected the PPRV nucleic acid as early as 3 day post infection (dpi) and up to 20 dpi in swab materials from the experimental samples.The assay was rapid and more sensitive than TaqMan and conventional RT-PCR in the detection of PPRV nucleic acid from the PPR suspected clinical samples of sheep and goats.Therefore,the established,simplified SYBR green rt RT-PCR is an alternative test to the already existing various diagnostic assays and could be useful for rapid clinical diagnosis with advantage in reducing risk of contamination.