%0 Journal Article %T Rapid Reliable EID50 Determination for live Newcastle Disease Viruses and Vaccines %J Zagazig Veterinary Journal %I Zagazig University, Faculty of Veterinary Medicine %Z 1110-1458 %A Eid, Amal A M %A Ismail, Abd El-Shakour N %A Gouda, Hagar F %A ElBakrey, Reham Mohamed %D 2022 %\ 12/01/2022 %V 50 %N 4 %P 276-286 %! Rapid Reliable EID50 Determination for live Newcastle Disease Viruses and Vaccines %K NDV %K ECE %K HAU %K EID50 %K live viral vaccines %R 10.21608/zvjz.2022.179646.1196 %X Newcastle disease (ND) was first recognized more than nine decades ago and continues to be a problem for poultry producers besides being enzootic in many countries including Egypt. Diagnostic and ND virus/vaccine titration are core objects in virus evaluation.   A rapid assay based on micro plate hemagglutination (HA) activity was applied to investigate its reliability as alternative method for virus titration.  A comparative determination of EID50 /0.1ml was carried out via chicken embryo (CE) inoculation for 35 Newcastle disease virus (NDV) strains. They are previously identified by pathogenicity indices and revealed variable virulence (lentogenic-mesogenic and velogenic). The data for both methods were analyzed using SPSS version 25. A Wilcoxon signed-rank test showed that HA titer method did not elicit a statistically significant change in median of reading Virus titer of samples with the median of standard embryonated chicken egg (ECE) method (Z = -0.197, p = 0.844). Spearman’s correlation coefficient (r= 0.42, p =0.01) showed a noteworthy moderate correlation between two methods. Heat map showed the differences between each pair of methods and the relationship between them. Bland-Altman plot revealed difference which fit normality distribution W=0.96, p=0.24. Accordingly, the use of HA activity assay for NDV/vaccine titration is a rapid easy and reliable, especially when needed for primary evaluation. %U https://zvjz.journals.ekb.eg/article_277415_8aa579e954b1eb31d7e9e22e8a13e1ea.pdf