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.

Animals↗

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Comparison of the genomic short regions of a vaccine strain (SA-2) and a virulent strain (CSW-1) of infectious laryngotracheitis virus (Gallid herpesvirus 1).

Restriction enzyme linkage maps were produced for the genomic short region of the virulent infectious laryngotracheitis virus (CSW-1 strain). After comparison with the equivalent restriction enzyme linkage maps for the infectious laryngotracheitis virus SA-2 strain (a vaccine strain), it was determined that the maps for the short regions of the two strains were identical, apart from a single section in each of the inverted terminal repeats. Each inverted terminal repeat of the SA-2 strain was discovered to contain 467 base pairs more DNA than the CSW-1 strain's inverted terminal repeats. This extra DNA was more precisely mapped entirely within the EcoRI fragments D and d of SA-2, which were found to form part of the SmaI fragments U and P of SA-2 and Q and b of SA-2 and to contain one SmaI restriction enzyme site.

Animals↗