Persistence of the tissue culture origin vaccine for infectious laryngotracheitis virus in commercial chicken flocks in Brazil.
Infectious laryngotracheitis (ILT) is a respiratory disease of great importance that causes serious economic losses in the poultry industry. Its control is based on biosecurity procedures and vaccination programs that use live attenuated vaccines such as tissue culture origin (TCO), chicken embryo origin (CEO), and vectored vaccines. However, problems have been reported, such as the reversion of virulence, virus latency, and field virus outbreaks. Several molecular techniques have been developed to differentiate between the field and vaccine strains. This study was conducted to determine the presence of infectious laryngotracheitis virus (ILTV) in Brazil from 2012 to 2014. PCR-RFLP (restriction fragment length polymorphism) was used to detect and differentiate ILTV strains; DNA sequencing and predictive RFLP analysis were also used for this purpose. Molecular analysis detected the presence of ILTV in 15 samples that were characterized as strains of TCO vaccine origin. This study showed that the ILTV TCO vaccine strain has been circulating in commercial chicken flocks in Brazil since its introduction during the 2002 outbreak.
Department of Pathology, School of Veterinary Medicine, University of São Paulo, Av. Prof. Orlando Marques de Paiva, 87, 05508-900, São Paulo, Brazil.
Silvana H Santander
SH
Parra
Department of Pathology, School of Veterinary Medicine, University of São Paulo, Av. Prof. Orlando Marques de Paiva, 87, 05508-900, São Paulo, Brazil.
Luis F
LF
Nuñez
Department of Pathology, School of Veterinary Medicine, University of São Paulo, Av. Prof. Orlando Marques de Paiva, 87, 05508-900, São Paulo, Brazil.
Claudete S
CS
Astolfi-Ferreira
Department of Pathology, School of Veterinary Medicine, University of São Paulo, Av. Prof. Orlando Marques de Paiva, 87, 05508-900, São Paulo, Brazil ajpferr@usp.br.
Antonio J Piantino
AJ
Ferreira
D000818:Animals; D001938:Brazil / Q000453:epidemiology; D002645:Chickens; D006566:Herpesviridae Infections / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D001352:Herpesvirus 1, Gallid / Q000276:immunology*; D022283:Herpesvirus Vaccines / Q000276:immunology*; D016133:Polymerase Chain Reaction / Q000662:veterinary; D012150:Polymorphism, Restriction Fragment Length; D011201:Poultry Diseases / Q000453:epidemiology* / Q000821:virology; D014613:Vaccines, Attenuated / Q000276:immunology
D022283:Herpesvirus Vaccines; D014613:Vaccines, Attenuated
CEO; PCR-RFLP; TCO; infectious laryngotracheitis virus; vaccine