Detection of infectious laryngotracheitis virus in chickens using a non-radioactive DNA probe

A DNA hybridization assay using a non-radioactive probe has been developed for the detection of infectious laryngotracheitis virus (ILTV) DNA. A 1.4-kilobase pair BamHI fragment of ILTV genomic DNA was cloned and then labeled by one of two methods; nick translation using 32P-dATP or non-radioactive labeling using a commercially available DNA labeling and detection kit. The non-radioactive DNA labeling method proved to be as sensitive as the radioactive method. Using the non-radioactive probe, ILTV DNA was readily detected in tracheal samples from acutely infected chickens and also from convalescent chickens at a time when viral antigen could no longer be detected by the enzyme-linked immunosorbent assay or the virus could no longer be reisolated. This technique provides a safe and effective means of identifying field outbreaks of ILTV and also may detect latent ILTV infections relatively quickly and inexpensively.