The Molecular Epidemiology Of Newcastle Disease In China And Protective Effect Of Different Genotypic Inactivated Vaccines

Newcastle disease (ND), also called Asian fowl plague or pseud-fowl plague, is an avian acute, highly contacted, contagious disease caused by Newcastle disease virus (NDV). Outbreak of Newcastle disease was first reported in poultry from Java, Indonesia in 1926. The disease currently has a worldwide distribution and causes tremendous loss to poultry industry. It was defined as a list A disease by the Office International des Epizooties (OIE). To date, vaccination against NDV is a common practice worldwide excluded some developed countries. NDV has a single-strand negative-sense RNA genome of 15186 bp with high variation and has been classified into nine genetic groups. So the research of epidemiology, especial molecular epidemical inspection, could be helpful to analyze and forecast NDV epidemical current and constitute effectual preventive measures.There are three main methods researching molecular epidemiology of NDV: the first is using monoclonal antibody to classify genotype, the second is restriction endonuclease map analysis, the third is amplification of specific nucleotide segment and protraction of phylogenic tree. Using RT-PCR technique, partial segment of F gene (535bp) were successfully amplified from 83 NDV isolated strains. The results of sequence analysis and genotypic study indicated that 5 strains belonged to genotype â…  , 9 belonged to genotype â…¡, 1 belonged to genotype â…¢, 3 belonged to genotype â…¥, and 65 belonged to genotype â…¦. The NDV epidemiological investigation of China in 2005 showed that the major genotype was genotype â…¦. In addition, 3 strains isolated from pigeon were mesogenic pathotypes.One genotype â…¡ NDV strain was isolated successfully in 2003 and designated as NDV026. Its cleavage site of F gene accorded with vesogenic character, and it was different from most same genotypic strains. So some biological characteristics were studied, and phylogenic tree was protracted according to the result of complete genomic sequence. In addition, its secondary structure and antigenic of F gene was analyzed and forecasted with DNAStar software.