Location: Endemic Poultry Viral Diseases ResearchTitle: Comparative nucleotide sequence analysis of three virulent strains of infectious laryngotracheitis virus (ILTV)) Author
Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 6/21/2010
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Infectious laryngotracheitis (ILT) is a very serious and widespread respiratory disease of chickens caused by gallid herpesvirus type 1, commonly named infectious laryngotracheitis virus (ILTV). For protection from ILT, chickens have traditionally been vaccinated with live-attenuated strains that have been attenuated by either multiple passages in embryonated eggs (chicken embryo origin [CEO]) or in tissue culture (tissue culture origin [TCO]) Once a vaccine strain has been introduced in the field, the differentiation between vaccines and field strains is difficult due to antigenic and genetic homogeneity that exists between vaccines and virulent field isolates. Safeguarding the poultry industry against virulent ILTV strains remains one the industry’s greatest challenges - the disease is primarily considered to have been restrained rather than well controlled. To investigate the genetic diversity of ILTV strains we have determined the nucleotide sequences of three virulent ILTV strains: USDA reference strain, genotype I (ATCC #71851)], the genotype V strain 63140/C/08/BR and the genotype VI strain 1874C5, using three different sequencing technologies. The USDA reference strain was sequenced from restriction endonuclease fragment libraries using dideoxynucleotide sequencing. The genotype V and VI strains were sequenced using the next generation technologies 454 pyrosequencing and Illumina, respectively. Each sequence was compared to the only ILTV sequence (NC006623) present within GenBank. The lengths of >30 open reading frames (ORFs) differ among the newly sequenced genomes and that of the NC006623 genome. This is not surprising since NC006623 represents a composite or “patchwork” of sequencing data from different strains. However, a strong correlation in ORF length of 70% exists between the newly sequenced genomes relative to NC006623, A comprehensive analysis of these genomes relative to partial sequences of the vaccine strain CEO will be presented.