Alireza Talebi

Phylogenetic characterization of virulent Newcastle disease viruses isolated during outbreaks in northwestern Iran in 2010

The northwest of Iran shares long borders with three neighboring countries; therefore, it is considered one of the main entry portals of Newcastle disease virus (NDV) into the country. Ten virulent NDVs were recovered from 19 poultry farms of various prefectures in northwestern Iran during Newcastle disease outbreaks in 2010. The isolates were genotypically analyzed using an F-gene-specific reverse transcription polymerase chain reaction (RT-PCR) assay. The amplified F gene (nucleotides 189-1666) sequences of the NDV isolates were compared phylogenetically with those of previously published strains in GenBank. All of the NDV isolates belonged to genotype VIIb and were closely related to some isolates from Iran, Russia, and Sweden. Therefore, it can be postulated that these isolates evolved from previously reported strains. The velogenic viruses carried the motif 112R-R-Q-K-R/F117 at the F0 cleavage site and a unique substitution of 190L→F which had never been reported in any NDV genotype VIIb isolate. They shared high sequence similarity with each other but were distinct from current NDV vaccines and NDV strains reported from other countries. This information is fundamental for improving the efficacy of controlling strategies and vaccine development for NDV.

Molecular typing of N gene and 3′ untranslated region of IBV field isolates and vaccine strains using RT-PCR and RFLP

Whole nucleocapsid (N) gene and 3′ untranslated region (UTR) of infectious bronchitis virus (IBV) vaccines and Iranian field isolates were amplified using reverse transcription and polymerase chain reaction (RT-PCR). The amplified fragments were subjected to digestion using two restriction endonuclease enzymes, AluI and MnlI. Five different restriction fragment length polymorphism (RFLP) patterns were generated using both enzymes, classifying IBV strains into five similar groups. Based on RT-PCR and RFLP analysis of the N gene and 3′ UTR, IBV vaccine strains H52, H120 and MA5 all from the same serotype generated identical patterns using both enzymes. Vaccine strain and field isolate of 4/91 also had the same pattern distinct from other IBVs. The IB88 vaccine strain and two other field isolates MNS-7862-1 and Ur1/09 had three different RFLP patterns distinguishable from each other and the other IBVs. In conclusion, RT-PCR and RFLP analysis of the N gene and 3′ UTR could be employed as a useful method for differentiating IBV strains especially in cases where S1 gene amplification is not successful because of its highly variable nature among different IBVs.