Sequence Analysis of the Hemagglutinin-Neuraminidase Gene of Newcastle Disease Virus from Punjab Pakistan

Abstract

Newcastle disease (ND) is a highly contagious disease that results in huge economic losses to the poultry industry worldwide including Pakistan. Despite the disease remained endemic, the genetic nature of the hemagglutinin-neuraminidase (HN) gene of NDV waited investigations in several Asian countries. This study was designed to gain insights into the genetics of HN gene of NDV isolated from Pakistan. Sequence analysis of the HN gene of NDV, isolated from thirteen outbreaks in broiler breeder (n=3) and broiler chickens (n=10), was performed. On the basis of clinical symptoms, mean death time (MDT, ~47 hours) and intracerebral pathogenicity index (ICPI, 1.5), the isolates were found to be velogenic. The phylogenetic analysis indicated a close relationship studied isolate to the Swedish (Chicken/Sweden/97) and Russian isolates (Sterna/Astr/2755/2001). A parallel comparison of HN gene of Chicken/Pak/2011 with other representative of known genotypes of NDV revealed 15 consistent nucleotide substitutions. Beside these substitutions, important mutations were observed at the crucial sites in the HN protein. This data provide foundation on the evolution of HN gene, possible role of HN gene in disease occurrence and emergence of novel genotypes of NDV.