Infectious laryngotracheitis (ILT) is an acute and highly contagious respiratory disease of chickens, with a worldwide distribution and leading to severe economic losses due to decreased growth rate, reduced egg production and mortality. It is caused by Gallid Herpesvirus 1. Disease is controlled by vaccination with 2 types of live attenuated ILT vaccines are produced by sequential passages in cell cultures (tissue culture origin, TCO) or embryonated eggs (chicken embryo origin, CEO). A strong evidence exists indicating that ILTV epizootics may originate from CEO-derived strains which can regain virulence and persist in the field. Here we report the development of 3 new PCR methods able to easily differentiate vaccine and CEO related field strains, which target genes are ORFE, ORFD and UL36. Two profiles were identified: one typical of CEO vaccines (characterized by no insertion-G-R-K) and other related to field strains (insertion-A-H-R). Using this method we tested 89 ILTV PCR positive samples collected from broilers, capons, layers and broiler breeders in the period 2004-2016 and identified two distinct profiles (CEO vaccine and field profiles) without observe mixed forms.
Tipizzazione del virus della laringotracheite infettiva aviare tramite protocolli di end point PCR.
Alessandra Piccirillo;
2016
Abstract
Infectious laryngotracheitis (ILT) is an acute and highly contagious respiratory disease of chickens, with a worldwide distribution and leading to severe economic losses due to decreased growth rate, reduced egg production and mortality. It is caused by Gallid Herpesvirus 1. Disease is controlled by vaccination with 2 types of live attenuated ILT vaccines are produced by sequential passages in cell cultures (tissue culture origin, TCO) or embryonated eggs (chicken embryo origin, CEO). A strong evidence exists indicating that ILTV epizootics may originate from CEO-derived strains which can regain virulence and persist in the field. Here we report the development of 3 new PCR methods able to easily differentiate vaccine and CEO related field strains, which target genes are ORFE, ORFD and UL36. Two profiles were identified: one typical of CEO vaccines (characterized by no insertion-G-R-K) and other related to field strains (insertion-A-H-R). Using this method we tested 89 ILTV PCR positive samples collected from broilers, capons, layers and broiler breeders in the period 2004-2016 and identified two distinct profiles (CEO vaccine and field profiles) without observe mixed forms.
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