Characterization of nucleoprotein gene of a velogenic Newcastle disease virus of genotype XIII.2.1

Newcastle disease (ND) is a highly contagious disease in poultry caused by the Newcastle disease virus (NDV). ND is considered one of the most important poultry diseases worldwide and may cause up to 100% mortality in infected chickens. Given the high mortality caused by NDV, the disease diagnosis and characterization of the circulating viral strains is critical. In this study, further studies have been performed to determine the molecular identity of a velogenic Newcastle disease virus genotype XIII.2.1 named RT30/2010, which is the first report of an XIII.2.1 NDV from Iran. In this study, virus purification was performed in two steps by the plaque purification method. The complete coding sequence of the NP gene was investigated to provide additional information about the nature and molecular epidemiology of RT30/2010. For this purpose, the NP gene of this virus was amplified using specific primers and cloned into PTZ57R/T vector. Rapid amplification of cDNA ends (RACE) was used to characterize the 3’ end of the virus genome, which includes the beginning region of the NP gene. Phylogenetic and genetic distance analysis of the nucleoprotein gene of RT30/2010 place the virus in a clade of Pakistani viruses of XIII.2.1. Therefore, RT30/2010 has a different origin compared to other viruses identified from Iran and is in the category of Newcastle disease viruses detected from Pakistan. The information from this study helps to further characterize the virus and makes it possible to use this virus as a challenge or a vaccine strain against XIII.2.1 viruses.