title: Full Genome Sequence-Based Comparative Study of Wild-Type and Vaccine Strains of Infectious Laryngotracheitis Virus from Italy.
abstract: Infectious laryngotracheitis (ILT) is an acute and highly contagious respiratory disease of chickens caused by an alphaherpesvirus, infectious laryngotracheitis virus (ILTV). Recently, full genome sequences of wild-type and vaccine strains have been determined worldwide, but none was from Europe. The aim of this study was to determine and analyse the complete genome sequences of five ILTV strains. Sequences were also compared to reveal the similarity of strains across time and to discriminate between wild-type and vaccine strains. Genomes of three ILTV field isolates from outbreaks occurred in Italy in 1980, 2007 and 2011, and two commercial chicken embryo origin (CEO) vaccines were sequenced using the 454 Life Sciences technology. The comparison with the Serva genome showed that 35 open reading frames (ORFs) differed across the five genomes. Overall, 54 single nucleotide polymorphisms (SNPs) and 27 amino acid differences in 19 ORFs and two insertions in the UL52 and ORFC genes were identified. Similarity among the field strains and between the field and the vaccine strains ranged from 99.96% to 99.99%. Phylogenetic analysis revealed a close relationship among them, as well. This study generated data on genomic variation among Italian ILTV strains revealing that, even though the genetic variability of the genome is well conserved across time and between wild-type and vaccine strains, some mutations may help in differentiating among them and may be involved in ILTV virulence/attenuation. The results of this study can contribute to the understanding of the molecular bases of ILTV pathogenicity and provide genetic markers to differentiate between wild-type and vaccine strains.
authors.affiliation: Department of Comparative Biomedicine and Food Science (BCA), University of Padua, Legnaro (Padua), Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Piccirillo
authors.affiliation: Department of Molecular Medicine, University of Padua (DMM), Padua, Italy.
authors.forename: Enrico
authors.initials: E
authors.lastname: Lavezzo
authors.affiliation: Department of Comparative Biomedicine and Food Science (BCA), University of Padua, Legnaro (Padua), Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Niero
authors.affiliation: Department of Virology, Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna (IZSLER), Brescia, Italy.
authors.forename: Ana
authors.initials: A
authors.lastname: Moreno
authors.affiliation: Department of Diagnostics, Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna (IZSLER), Forlì, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Massi
authors.affiliation: Department of Molecular Medicine, University of Padua (DMM), Padua, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Franchin
authors.affiliation: Department of Molecular Medicine, University of Padua (DMM), Padua, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Toppo
authors.affiliation: Department of Molecular Medicine, University of Padua (DMM), Padua, Italy.
authors.forename: Cristiano
authors.initials: C
authors.lastname: Salata
authors.affiliation: Department of Molecular Medicine, University of Padua (DMM), Padua, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Palù
mesh_terms: D000596:Amino Acids / Q000235:genetics; D001483:Base Sequence; D019143:Evolution, Molecular; D016679:Genome, Viral; D001352:Herpesvirus 1, Gallid / Q000235:genetics*; D009711:Nucleotides / Q000235:genetics; D016366:Open Reading Frames / Q000235:genetics; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D014613:Vaccines, Attenuated / Q000276:immunology*
chemical_list: D000596:Amino Acids; D009711:Nucleotides; D014613:Vaccines, Attenuated