Thermostability of haemagglutinative activity of reconstituted newcastle disease vaccine virus strains at fridge and shelf-storage temperatures

摘要

Themostability of viral haemagglutinin measured by the persistence in haemagglutinaton (HA) titers was determined for Hitchner-Bl (Bl), Lasota (L) and Komarov (K) strains of Newcastle Diseases Virus (NDV) at 4 deg C and 25 deg C storage temperatures, respectively. With sampling for HA titers at selected intervals post-storage, a two-step (2log_2) decline in initial (stock) titers was adopted as evidence of loss of stability of HA titers (LST). Thus, on the basis of this criterion, LST-times for B1, L and K strains occurred after 35, 11, and 8 days, respectively, at 4 deg C. The corresponding times at 25 deg C were after the 19~th, 5~th day, respectively. These results depicted the NDV-Bl as the most stable strain at the two test temperatures, which represented approximately, fridge and shelf-storage temperatures. The relevance o this to the other determinant factors for a thermostable Newcastle Disease (ND) vaccine for rural poultry stock is discussed.