Genetic Evolution and Development of Recombinant vaccine Against newcastle Disease for Chicken in Pakistan

Abstract

Newcastle disease (ND) is considered as a highly infectious disease of poultry worldwide. The commercial broiler industry is highly susceptible to virulent NDV, the data indicating heavy losses and documentary proof is available on NDV surveillance program. However, a little is known regarding the maintenance and enzootic trends of vNDV infection level in domestic and wild birds. Poor vaccination strategy as well as the existence of virulent form of NDV in the domestic birds indicates a root cause of the occurrence of disease eruption in the developing countries. Here, we report the eleven complete genome sequences of NDV from lovebird parrot (n=1) and exotic parakeets (n=3), backyard chickens (n=5), peacock (n=1) and pheasant (n=1). The complete genome lengths of all isolates were 15,192 nucleotides (nt) with same virulenceassociated cleavage site (112-RRQKRF-117) and selected ones have intracerebral pathogenicity index (ICPI) values ranging from 1.50 to 1.86, which is typical of vNDV. The deduced amino acid residues analyses have shown a number of substitution mutations in the functional domains of fusion and hemagglutinin-neuraminidase proteins. Phylogenetic analysis showed all NDV isolates belong to sub-genotypes VIIi within the genotype VII of class II. The isolation of highly similar viruses (98-99%) during 2011-16 provides the evidence of an epidemiological links between poultry, domestic and wild birds. Our results also support the existence of fifth panzootic as these viruses primarily isolated from South Asia, Middle East and Indonesia and recently spread into Eastern Europe. Active surveillance of these newly emerging viruses to determine their evolution is one of the most realistic strategies for preventing and controlling NDV outbreaks.