Abstract
The aims of this study were to compare three commercial porcine reproductive and respiratory syndrome virus (PRRSV) real-time RT-PCR assays for detection of genetically diverse PRRSV isolates in serum, semen, blood swabs, and oral fluids collected from experimentally-infected boars, and to evaluate the effects of sample pooling. Six groups of 3 boars negative for PRRSV were each inoculated with one of six PRRSV isolates (sharing 55-99% nucleotide sequence identity in ORF5). Samples were collected on days post-inoculation (dpi) -2, 1, 3, 5, 7, 14 and 21 and tested by one of three commercially available real-time RT-PCR assays (AB, TC, AD). At dpi 1, all assays detected at least one positive sample in each group. The highest detection rates were on dpi 3 and dpi 5. Between dpi 1 and 7, serum samples had the highest detection rate (90%) with 100% agreement between tests, followed by blood swabs (Kappa = 0.97) and semen (Kappa = 0.80). Oral fluids had the lowest detection rates (AB: 55%; TC: 41%; AD: 46%) and the highest disagreement between kits (Kappa = 0.63). Pools of five samples did not reduce the detection rates if there was one positive sample with a high amount of viral RNA in the pool. Serum and blood swab samples had shorter turn-around times for RNA extraction. The AB assay had a 1.6 times shorter PCR reaction time. In summary, serum and blood swabs had the best performance with highest detection rates and agreement between assays and shortest turn-around time.Gerber PF, O'Neill K, Owolodun O, Wang C, Harmon K, Zhang J, Halbur PG, Zhou L, Meng XJ, Opriessnig T. Comparison of commercial real-time RT-PCR assays for reliable, early and rapid detection of heterologous strains of porcine reproductive and respiratory syndrome virus (PRRSV) in experimentally infected or negative boars using different sample types (semen, oral fluids, serum, blood swabs). 2012. Journal of clinical microbiology [accepted].
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