Authors: Timothy J Mahony Robyn N Hall Stephen WalkdenBrown Joanne Meers Jennifer L Gravel Lani West Vanessa Hardy AFM Fakhrul Islam Elizabeth V Fowler Neena Mitter
Publish Date: 2015/07/07
Volume: 51, Issue: 1, Pages: 85-95
Abstract
Meleagrid herpesvirus 1 MeHV1 or turkey herpesvirus has been widely used as a vaccine in commercial poultry Initially these vaccine applications were for the prevention of Marek’s disease resulting from Gallid herpesvirus 2 infections while more recently MeHV1 has been used as recombinant vector for other poultry infections The construction of herpesvirus infectious clones that permit propagation and manipulation of the viral genome in bacterial hosts has advanced the studies of herpesviral genetics The current study reports the construction of five MeHV1 infectious clones The in vitro properties of viruses recovered from these clones were indistinguishable from the parental MeHV1 In contrast the rescued MeHV1 viruses were significantly attenuated when used in vivo Complete sequencing of the infectious clones identified the absence of two regions of the MeHV1 genome compared to the MeHV1 reference sequence These analyses determined the rescued viruses have seven genes UL43 UL44 UL45 UL56 HVT071 sorf3 and US2 either partially or completely deleted In addition single nucleotide polymorphisms were identified in all clones compared with the MeHV1 reference sequence As a consequence of one of the polymorphisms identified in the UL13 gene four of the rescued viruses were predicted to encode a serine/threonine protein kinase lacking two of three domains required for activity Thus four of the recovered viruses have a total of eight missing or defective genes The implications of these findings in the context of herpesvirus biology and infectious clone construction are discussed
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