Razi Vaccine & Serum Research Institute Veterinary Research & Biological Products 3041-9417 34 4 2021 12 22 Evaluation of the infectious dose and the rate of replication of Lasota and Cloned Lasota vaccines in Newcastle disease Evaluation of the infectious dose and the rate of replication of Lasota and Cloned Lasota vaccines in Newcastle disease 2 7 122351 10.22092/vj.2020.342570.1713 FA M Abdoshah Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran H Hosseini Department of Clinical Sciences, Faculty of Veterinary Medicine, Karaj Branch, Islamic Azad University, Alborz, Iran M. H Fallah Mehrabadi Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran A Ghalyanchi Laageroudi Department of Microbiology and Immunology, University of Tehran, Faculty of Veterinary Medicine, Tehran, Iran Journal Article 2020 04 10 Newcastle Disease is a fatal viral disease and considered a global threat to the poultry industry all over the world. Both live and killed Lentogenic, and Mesogenic vaccines are used to control this disease. One of the common vaccines used in preventing strategy of ND is the Lasota as a pneumotropic strain, which is available in two forms of Lasota and Cloned Lasota, internally produced (Razi Institute) and imported from various companies in the country, and one of the most controversial issues was the difference between Lasota and Cloned Lasota vaccines in farm conditions. In this study, the first step in the comparison was to determine the EID50 and the rate of replication, which was performed. The results showed that the used vaccines had significant differences in the amount of infectious dose. Internally produced vaccines (Razi Vaccine and Serum Institute) had an appropriate infectious dose and reproduction rate. Regarding the difference in the rate of reproduction, the primary results revealed that there is diversity between different vaccines, and this is the first step in confirming the field feedback. Due to a large amount of variety in infectious dose, in controlling the quality of vaccines, it is suggested, in addition to observation of international standard guidelines, other indicators which are monitor to their effectiveness keep to continue seriously and pay attention to cold chain and standard transport conditions. Newcastle Disease is a fatal viral disease and considered a global threat to the poultry industry all over the world. Both live and killed Lentogenic, and Mesogenic vaccines are used to control this disease. One of the common vaccines used in preventing strategy of ND is the Lasota as a pneumotropic strain, which is available in two forms of Lasota and Cloned Lasota, internally produced (Razi Institute) and imported from various companies in the country, and one of the most controversial issues was the difference between Lasota and Cloned Lasota vaccines in farm conditions. In this study, the first step in the comparison was to determine the EID50 and the rate of replication, which was performed. The results showed that the used vaccines had significant differences in the amount of infectious dose. Internally produced vaccines (Razi Vaccine and Serum Institute) had an appropriate infectious dose and reproduction rate. Regarding the difference in the rate of reproduction, the primary results revealed that there is diversity between different vaccines, and this is the first step in confirming the field feedback. Due to a large amount of variety in infectious dose, in controlling the quality of vaccines, it is suggested, in addition to observation of international standard guidelines, other indicators which are monitor to their effectiveness keep to continue seriously and pay attention to cold chain and standard transport conditions. https://vj.areeo.ac.ir/article_122351_6774599b5970c5c593469a1e06f7c17b.pdf