Das, SutopaBarua, Jonmoni2024-01-092024-01-092022https://krishikosh.egranth.ac.in/handle/1/5810206075Duck plague (DP) or Duck Viral Enteritis (DVE) is an acute contagious herpesvirus infection of ducks and waterfowl of the family Anatidae of the order Anseriformes. Anatid Herpesvirus-1 (AHV-1) or duck enteritis virus (DEV)of the family Herpesviridae is the responsible agent for DP or DVE which is a member. The disease is known to have a global distribution and is associated with significant economic losses worldwide. The only method for preventing and controlling the disease is vaccination. Also, an active decontamination process for an effective vaccination programme in field conditions is important. So, in the present study emphasis has been laid to understand the physicochemical properties of a DPV vaccine strain along with evaluation of thermostability of freeze-dried vaccine with different combinations of stabilizers. In the present study, a vaccine strain of DPV available in the DBT-ADMaCDepartment of Veterinary Microbiology, College of Veterinary Science, AAU, Khanapara was revived in CEF and selected for study on the basis of identity with DPV by observing CPE, PCR and molecular characterization. Characteristic CPE like vacuolation, rounding, syncytium formation and ultimately detachment of cells were observed, in case of PCR band was observed at 1510 bp which proves similar identity with DPV. Molecular characterization revealed homology with DPV isolates from India (Kerala and Assam) and China. Quantitation was done at each step to find out the titre by TCID50/ml after every evaluation right from initial titre, loss of titre during lyophilization, loss of titre during the evaluation of physicochemical treatment, stability evaluation of the freeze-dried vaccine vial, as well as reconstituted vials. The initial titre was found to be 6.9±0.17. The vaccine virus was found to be sensitive to temperatures exceeding 56ºC and above, pH 3 and below, and pH 11 and above. It was also found sensitive to ether and trypsin. On sterility test, no growth was found on the culture. Lyophilization was carried out with 3 combinations of stabilizers namely LS, PTI and LHT. On quality evaluation, PTI and LHT showed uniform cake formation along with minimal loss of titre due to lyophilization. To check the thermostability of freeze-dried vaccines and reconstituted vaccines, vials were exposed at different temperatures. Among the freeze-dried vaccine, LHT could keep the highest titre when exposed to different temperatures and sampled at different time intervals. Although, LS and PTI too could keep with the infectivity titre with minimal loss of titre. In case of the reconstituted vaccine, NSS showed better stability at different temperatures than PBS, though the differences were minimum between the two. Finally, it can be concluded that LHT is one of the better stabilizers for DPV freeze-dried vaccine production. Alternatively, LS and PTI can be used by utilizing a suitable freeze-drying protocol. PBS and NSS both can be used as a diluent for the lyophilized DPV vaccine although in this study NSS was found to be superior. Hence, stabilizer LHT with diluent NSS was found to be superior for the DPV vaccine strain under this study.EnglishThesis