Аннотация
This article presents the results of the work to refresh and optimize the cultivation of the Newcastle disease virus (NDV) La- Sota strain (AV-0330) in embryonated chicken eggs to obtain high-quality viral material suitable for gene cloning and the development of vector constructs. One of the main objectives was to determine the optimal infective dose and passage level that would ensure maximum virus yield while maintaining embryo viability. The virus was cultured in 10-day-old embryos, and infectious and hemagglutinating activity was assessed at doses ranging from 10 to 1.000,000 EID50. Titers were calculated using the Reed–Muench method. Molecular identification was performed by RT-PCR using custom-designed primers specific to the M, F, and HN genes, each containing restriction sites for downstream cloning. The results demonstrated that optimal replication occurred at doses of 1,000–10,000 EID50, with infectious activity reaching 9.4±0.06 log10 EID50/mL, hemagglutination titers up to 1:256 and no embryo mortality. Serial passaging up to the seventh generation showed a stable increase in infectivity starting from the fifth passage. All virus-containing suspensions remained microbiologically sterile. Amplification of the M, F, and HN genes yielded specific fragments of the expected lengths, confirming the integrity of the viral RNA and the suitability of the material for molecular cloning. Thus, the optimized cultivation of the La-Sota NDV strain and the application of validated primer systems provide a reliable foundation for generating recombinant constructs and confirm the potential of NDV as a platform for vaccine development in both veterinary medicine and biomedicine.