A sensitive nested-polymerase chain reaction protocol to detect infectious Laryngotracheitis virus / A sensitive nested-polymerase chain reaction protocol to detect infectious Laryngotracheitis virus

ABSTRACT

Background: Infectious laryngotracheitis virus (ILTV) is a member of the family Herpesviridae that has a worldwide distribution, although it is well controlled in areas of intensive production in which periodic outbreaks of the disease occur. ILTV is an important respiratory pathogen of chickens that may cause severe or mild disease in layers and broilers. Severe disease is characterized by respiratory depression, gasping, expectoration of bloody exudate and high mortality. Mild diseased chickens exhibit milder clinical signs and low mortality, and laboratory techniques are mandatory for a fi nal diagnosis. Several techniques have been described for the detection of ILTV, however they have disadvantages that constrains their use in routine diagnosis. Viral multiplication is limited to respiratory tissue, which makes the trachea the ideal site to look for the virus. The purpose of the present study was to develop a sensitive and specifi c nested Polymerase Chain Reaction (PCR) protocol to detect ILTV DNA directly from tracheal swabs of naturally or experimentally infected chickens.Materials, Methods & Results: The nested-PCR was carried out with two sets of primers selected from a portion of the ILTV thymidine kinase gene. PCR sensitivity was determined by using fi ve-fold serial dilutions of a commercial laryngotracheitis vaccine. PCR was specifi c as determined by testing

RESUMO

Background: Infectious laryngotracheitis virus (ILTV) is a member of the family Herpesviridae that has a worldwide distribution, although it is well controlled in areas of intensive production in which periodic outbreaks of the disease occur. ILTV is an important respiratory pathogen of chickens that may cause severe or mild disease in layers and broilers. Severe disease is characterized by respiratory depression, gasping, expectoration of bloody exudate and high mortality. Mild diseased chickens exhibit milder clinical signs and low mortality, and laboratory techniques are mandatory for a fi nal diagnosis. Several techniques have been described for the detection of ILTV, however they have disadvantages that constrains their use in routine diagnosis. Viral multiplication is limited to respiratory tissue, which makes the trachea the ideal site to look for the virus. The purpose of the present study was to develop a sensitive and specifi c nested Polymerase Chain Reaction (PCR) protocol to detect ILTV DNA directly from tracheal swabs of naturally or experimentally infected chickens.Materials, Methods & Results: The nested-PCR was carried out with two sets of primers selected from a portion of the ILTV thymidine kinase gene. PCR sensitivity was determined by using fi ve-fold serial dilutions of a commercial laryngotracheitis vaccine. PCR was specifi c as determined by testing