title: High-throughput real-time RT-PCR assay to detect the exotic Newcastle Disease Virus during the California 2002--2003 outbreak.
abstract: During the 2002--2003 Exotic Newcastle Disease (END) outbreak in Southern California, a high-throughput real-time reverse transcriptase-polymerase chain reaction (RRT-PCR) system was developed to respond to the large diagnostic and surveillance sample workload. A 96-well RNA extraction method, using magnetic bead technology, combined with a 96-well RRT-PCR assay, allowed 1 technician to process and test more than 400 samples per day. A 3-technician team could complete testing on approximately 1,900 samples per day. The diagnostic sensitivity of the high-throughput RRT-PCR assay was 0.9967 (95% CI 0.9937-0.9997) based on 926 virus isolation confirmed positive samples. Diagnostic specificity using an initial 434 virus isolation confirmed negative samples was 100%. A diagnostic specificity of 0.9999 (95% CI 0.9999, >0.9999) was subsequently calculated on the basis of 2 false-positive results among 65,343 surveillance samples collected after the final END-positive case was confirmed in May 2003. Assay performance over 500 replicates, including reproducibility of the combined extraction and RRT-PCR amplification steps yielded a standard deviation of 0.70 RRT-PCR cycle thresholds (Ct) and a standard deviation of 0.59 Ct for the RRT-PCR steps alone. The high-throughput RRT-PCR developed for END contributed significantly to the 2002--2003 END control effort, reducing the predicted timeline for eradication from 3 years to just 11 months, primarily because of the large number of samples that could be rapidly tested. The 96-well approach described for high-throughput END RRT-PCR could be adapted to other rapid, high-volume testing needs, as required for potential foreign animal disease responses or intensive surveillance efforts.
authors.affiliation: California Animal Health and Food Safety Laboratory, Davis, CA 95616, USA.
authors.forename: Beate M
authors.initials: BM
authors.lastname: Crossley
authors.forename: Sharon K
authors.initials: SK
authors.lastname: Hietala
authors.forename: Liu-Mei
authors.initials: LM
authors.lastname: Shih
authors.forename: Lou
authors.initials: L
authors.lastname: Lee
authors.forename: Evan W
authors.initials: EW
authors.lastname: Skowronski
authors.forename: Alex A
authors.initials: AA
authors.lastname: Ardans
mesh_terms: D000818:Animals; D002140:California / Q000453:epidemiology; D002645:Chickens; D004196:Disease Outbreaks / Q000662:veterinary; D009980:Influenza A virus / Q000302:isolation & purification; D009521:Newcastle Disease / Q000175:diagnosis* / Q000453:epidemiology; D009522:Newcastle disease virus / Q000235:genetics / Q000302:isolation & purification*; D011200:Poultry / Q000821:virology; D012367:RNA, Viral / Q000302:isolation & purification*; D012044:Regression Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods / Q000662:veterinary*; D012680:Sensitivity and Specificity
chemical_list: D012367:RNA, Viral