In Situ Hybridization for the Detection of Infectious Laryngotracheitis Virus in Sections of Trachea from Experimentally Infected Chickens

An in situ hybridization procedure for the detection of infectious laryngotracheitis virus (ILTV) in experimentally infected chickens is described. Formalin-fixed, paraffin-embedded sections of trachea, taken from chickens on days 3–10 post-inoculation (p.i.) with ILTV were hybridized with a mixture of 2 biotinylated, polymerase chain reaction-generated DNA fragments. The fragments correspond to sequences of the ILTV glycoprotein C and thymidine kinase genes. In situ hybridization was seen in 7 out of 7 chickens examined on day 3 p.i., 2 out of 2 examined on day 4 p.i. and 3 out of 3 examined on day 5 p.i. No hybridization was observed in 3 out of 3 chickens examined on day 10 p.i. ILTV nucleic acid was detected in nuclei of degenerated tracheal epithelial cells and in intranuclear inclusion bodies of syncytia.