Submitted to: American Association of Avian Pathologists
Publication Type: Abstract Only
Publication Acceptance Date: January 1, 2012
Publication Date: August 4, 2012
Citation: Diel, D.G., Da Silva, L.H., Miller, P.J., Afonso, C.L. 2012. Genetic diversity of avian paramyxovirus type 1: defining Newcastle disease virus genotypes [abstract]. American Association of Avian Pathologists. p.22. Technical Abstract: All Newcastle disease virus (NDV) isolates belong to a single serotype of avian paramyxovirus type-1 (APMV-1); however, significant genetic diversity is recognized between different NDV isolates. Historically, two systems have been used to classify NDV into lineages or genotypes, with both systems relying on the phylogenetic analysis of the F (fusion) gene for their classification. The genotyping system is the most widely accepted; however, the lack of objective criteria to define genotypes and subgenotypes makes the classification of new isolates difficult. Here we propose an approach to classify NDV isolates based on the phylogenetic relationship and evolutionary distances between isolates. The complete F gene sequence of class I (n=102) and class II (n=599) viruses were used for phylogenetic reconstruction and to infer the evolutionary distances between groups. The mean evolutionary distance between groups was determined and a cutoff value was set for the classification into genotypes or subgenotypes. Results of our study revealed that Class I viruses comprise a single genotype (genotype 1) which is divided in three subgenotypes (1a, 1b and 1c). Class II comprise 15 genotypes (I to XV), including the previously established genotypes I through IX, and XI, and five new genotypes consisting of genotypes X (previously classified as subgenotype IIa), XII (isolates from China and South America), XIII and XIV (previously classified as lineage 7), and XV (viruses from Asia). The establishment of objective criteria to define major NDV taxonomic groups is an essential step to improve our understanding of NDV epidemiology and evolution.