Submitted to: Virus Genes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/30/2008
Publication Date: 12/9/2008
Citation: Perozo, F., Villegas, P., Afonso, C.L. 2008. Genomic comparison of the complete coding and intergenic regions of the VG/GA Newcastle disease virus and its respirotropic clone 5. Virus Genes. 37(2):161-167.
Interpretive Summary: The VG/GA virus is used worldwide as a vaccine strain and its tissue tropism is extremely important for protection against virulent NDV. To understand the mechanism involved in tissue tropism we have compared the entire genomic sequences of two highly related vaccine virus that display different characteristics during infection of poultry. The Villegas-Glisson/University of Georgia (VG/GA) strain of Newcastle disease virus (NDV)that replicate in the intestinal tract and a plaque purified clone (clone 5) that preferentially replicates in the respiratory tract have shown differences at the nucleotide and protein sequences that may be responsible for the differences in tropism.
Technical Abstract: The complete genome sequence of the Villegas-Glisson/University of Georgia (VG/GA) strain of Newcastle disease virus (NDV) and of a plaque purified clone (clone 5) exhibiting a different phenotype were sequenced and analyzed. The VG/GA strain, isolated from the intestine of healthy turkeys replicates in the respiratory and intestinal tract of chickens. The VG/GA virus is used worldwide as a vaccine strain and its tissue tropism is extremely important for protection against virulent NDV which target both intestinal and respiratory epithelia inducing severe gross and microscopic damage. The clone 5 was selected as a viral subpopulation from the respiratory tract of birds vaccinated with the VG/GA strain and can not be recovered from the intestine. To assess the genomic basis of the differences between both viruses tissue tropism, a modified primer sequence-independent amplification method was used for full genome sequencing. The full genome analysis grouped the VG/GA strain and the Clone 5 within class II, genotype II viruses and showed that they are closely related to classic vaccine strains, such as, LaSota and B1. Differences at the nucleotide and amino acid level were observed between the VG/GA strain and the Clone 5 and between these and other respirotropic and enterotropic vaccine strains; these differences may explain the differential phenotype observed in the VG/GA strain.