ABSTRACT
In the last couples of years, Egyptian poultry farms have faced many outbreak mortalities. Newcastle disease virus (NDV) was suggested as one leading cause of these mortalities. In the current study, we characterized the NDV from outbreaks affecting poultry farms in Egypt between 2012 and 2014. Different organ tissues were collected from twenty different chicken farms showing clinical signs of NDV infection in El-Behira and Kafr-Elshiekh provinces. Inoculation of the processed samples in 10-day-old embryonated chicken specific-pathogen-free eggs indicated presence of haemagglutinating agent in 12 samples. These haemagglutinating agents were confirmed as NDV by real-time reverse transcription polymerase chain reaction (rRT-PCR). In the employed rRT-PCR assay, two sets of primers and probes were used. A first primer- probe set was designed to detect sequences from a conserved region of the Matrix gene that recognizes a diverse set of virus isolates. A second primer-probe set was targeted to comprise the cleavage site of the F gene and to detect potentially virulent NDV isolates. The rRT-PCR results revealed that seven detected ND viruses were of velogenic type, whereas the other five detected ND viruses were of lentogenic nature. Sequencing of two suspected ND velogenic viruses was carried out. The phylogenetic analysis based on the partial sequence of F protein gene showed that the detected viruses were closely related to viruses from genotype VII subgroup D. Furthermore, the nucleotide and amino acid analysis approved the previous finding. Overall, the study confirmed circulating of NDV genotype VII among Egyptian poultry farms.