PRELIMINARY FINDINGS ON THE THERMOSTABILITY OF THREE IMMUNOGENfC STRAINS OF NEWCASTLE DISEASE VIRUS UNDER REGIMEN OF HIGH TEMPERATURE

Abstract

Haemagglutination (HA) test was employed to determined the stability of HA titersof reconstituted form of Hitchner-BI (B1), Lasota (L) and Komarov (K) strains of Newcastle Disease Virus (NDV) in vaccines at 4SDC and 56°C respectively. The temperature treatment method was through incubation (in water bath) of the reconstituted vaccines at selected temperatures and sequential sampling of each vaccines for the determination of HA titers. A two-step (21og₂) decline in titer was adopted as evidence of loss of stability. Thus, on the basis of this criterion, loss of stability was after 5 hours for both B1 and L strains and after 23 hours for K strain at 45°C. The corresponding period at 56OC for both B1 and L strains were less than 10 minutes each and longer than the 10 minutes for K strain. The result therefore showed that the NDV-K strain was the most stable at high temperatures. Further studies are required for the characterization of the three strains after reconstitution at low and intermediate temperatures. It is believed that the findings will enhance the understanding of the potentials of these strains ill the development and application of thermostable Newcastle Disease (NI)) vaccine for rural poultry.