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.
Ontario Ministry of Agriculture and Food, Veterinary Services Laboratory, Guelph, Canada.
D W
DW
Key
B C
BC
Gough
J B
JB
Derbyshire
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E
Nagy
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