Development and evaluation of a non-isotopically labeled DNA probe for the diagnosis of infectious laryngotracheitis.
A digoxigenin-labeled cloned infectious laryngotracheitis virus (ILTV) DNA fragment was evaluated as a nonradioactive alternative probe in the diagnosis of infectious laryngotracheitis. The dot-blot hybridization protocol was optimized and was capable of detecting 40 pg of purified ILTV DNA and as few as 50 ILTV-infected chicken embryo liver cells. The utility of this approach for diagnostic use was evaluated through four ILTV inoculation trials using a mild field isolate, a virulent challenge strain, a tissue-culture-origin vaccine, and an egg-origin vaccine. Birds were examined for clinical signs of ILT, and conjunctival and pharyngeal swabs from inoculated and sentinel birds were tested for ILTV by the digoxigenin-labeled probe and by virus isolation. In general, higher numbers of ILTV-positive samples were detected by both assays from conjunctival swabs. For the non-vaccine strains, detection by dot-blot hybridization was equivalent to that for virus isolation. However, for the two vaccine strains, there was some lack of correlation between the dot-blot results and the virus-isolation results. The kappa values between virus-isolation results and dot-blot results for the tissue-culture-origin vaccine, egg-origin vaccine, Ont 1598 field isolate, and virulent strain were 0.00, 0.16, 0.39, and 0.24, respectively, for pharyngeal samples and 0.19, 0.29, 0.58, and 0.48, respectively, for conjunctival samples.
Key
D W
DW
Ontario Ministry of Agriculture and Food, Veterinary Services Laboratory, Guelph, Canada.
Gough
B C
BC
Derbyshire
J B
JB
Nagy
E
E
D000818:Animals; D002642:Chick Embryo; D002645:Chickens; D003228:Conjunctiva / Q000821:virology; D015342:DNA Probes; D004076:Digoxigenin; D006566:Herpesviridae Infections / Q000175:diagnosis / Q000662:veterinary* / Q000821:virology; D001352:Herpesvirus 1, Gallid / Q000235:genetics* / Q000276:immunology / Q000302:isolation & purification; D015336:Molecular Probe Techniques / Q000706:statistics & numerical data / Q000662:veterinary; D010614:Pharynx / Q000821:virology; D011201:Poultry Diseases / Q000175:diagnosis* / Q000821:virology; D012680:Sensitivity and Specificity; D014765:Viral Vaccines
D015342:DNA Probes; D014765:Viral Vaccines; D004076:Digoxigenin