Pathogenicity of a Very Virulent Strain of Marek's Disease Herpesvirus Cloned as Infectious Bacterial Artificial Chromosomes

Lorraine P Smith,Jennifer Simpson,Lawrence J Petherbridge,Venugopal Nair,Susan J Baigent

doi:10.1155/2011/412829

Lorraine P Smith, Jennifer Simpson + Show 3 more

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https://doi.org/10.1155/2011/412829

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Abstract

Bacterial artificial chromosome (BAC) vectors containing the full-length genomes of several herpesviruses have been used widely as tools to enable functional studies of viral genes. Marek's disease viruses (MDVs) are highly oncogenic alphaherpesviruses that induce rapid-onset T-cell lymphomas in chickens. Oncogenic strains of MDV reconstituted from BAC clones have been used to examine the role of viral genes in inducing tumours. Past studies have demonstrated continuous increase in virulence of MDV strains. We have previously reported on the UK isolate C12/130 that showed increased virulence features including lymphoid organ atrophy and enhanced tropism for the central nervous system. Here we report the construction of the BAC clones (pC12/130) of this strain. Chickens were infected with viruses reconstituted from the pC12/130 clones along with the wild-type virus for the comparison of the pathogenic properties. Our studies show that BAC-derived viruses induced disease similar to the wild-type virus, though there were differences in the levels of pathogenicity between individual viruses. Generation of BAC clones that differ in the potential to induce cytolytic disease provide the opportunity to identify the molecular determinants of increased virulence by direct sequence analysis as well as by using reverse genetics approaches on the infectious BAC clones.

Highlights

Herpesviruses are major pathogens associated with a number of diseases both in man and animals
We report on the cloning of the hypervirulent UK Marek’s disease viruses (MDVs) strain C12/130 to elucidate some of its unique biological properties
We report here the cloning of the full-length genome of a hypervirulent UK MDV strain C12/130 that induces acute cytolytic disease with brain lesions

Summary

Introduction

Herpesviruses are major pathogens associated with a number of diseases both in man and animals. Since herpesviruses have large genomes, between 120 kbp–230 kbp in size, the manipulation of the viral genomes to identify the molecular determinants and mechanisms of pathogenesis is difficult. The use of bacterial artificial chromosome (BAC) as vectors for cloning the large DNA virus genomes as a single-copy mini-F plasmid [1] has opened new avenues for carrying out reverse genetics approaches for understanding herpesvirus gene functions [2]. The genomes of a number of virulent and attenuated Mardiviruses have been cloned as infectious BAC clones [4,5,6,7,8,9,10,11] and used to identify the determinants of virulence as well as for expression of foreign genes [12,13,14]

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