Sequencing And Analysis Of The Genomes Of Three Newcastle Disease Viruses Isolated From Different Avian

Newcastle disease (ND) is one of the most important diseases of poultry. It can cause severe disease and high mortalities in susceptible birds. And the pathogen of Newcastle disease is Newcastle disease virus (NDV). The nucleocapsid of NDV is covered by the envelope. NDV has a negative-sense, single-stranded RNA genome of15kb, which contains six genes in the order of3’-NP-P-M-F-HN-L-5’, encoding six proteins (nucleocapsid protein, phospho protein, matrix protein, fusion protein, hemagglutinin-neuraminidase protein and large protein respectively).In our experiment, ten pairs of specific primers were designed and synthesized based on the entire genomic sequence data of Newcastle Disease Virus present in GenBank. The specific gene fragments were amplified by RT-PCR. And the products of the RT-PCR were cloned to the pMD18-T vector. The correct recombinant plasmids which were identified by PCR were sent to the biotechnology company to be sequenced. According the sequence report, we got the complete genomic sequences of the WFooC、WFooD and WFooG. And then, they were analysised by DNASTAR.Based on the analysis, we got the following conclusions.First, the entire genomic sequences of three NDV strains consisted of15192nt, which were the same in length to NDV ZJ1, NA-1strains, but were6nt longer than LaSota, Clone30and B1strains in GenBank.Second, phylogenetic analysis revealed that WFooD was similar to WFooC and WFooG. Especially, WFooD and WFooG were highly homologous. Third, WFooC、WF00D、 WFooG、ZJ1、NA-1、SF02and FMW were of the genotype Ⅶ, which has become the predominant genotype of NDV responsible for most of outbreaks of ND in China in recent years. But, the government standard strain F48E8belonged to genotype IX and traditionary low virulence strain LaSota、B1、Clone30belonged to genotype Ⅱ. There were much difference between NDV vaccine and the strains responsible for most of outbreaks of ND in China in recent years.Fourth, NDV genomic structure possessed conservatism in the inheritance level. The evolution of np、p、m、f、hn and l carried out simultaneously. l gene was highly conserved, but p gene changed much. Fifth, the mutation of the six genes coding sequences were regular in WFooC、WFooD and WFooG Most of them were silent mutations.Our research explored classification and the evolutionary relationship of WFooC、 WFooD and WF00G at the molecular level. This study fulfilled the biological information database of NDV. It could be the basic of studying the molecular mechanisms of NDV cross-species infection. Also, it provided foundation to make research on reverse genetics.