Name of instrument, m RealTime System composed of the msp and mrt modules. Country where designed/Manufactured/Reagents. The Abbott m System comprises the msp and mrz instruments, which are operated with separate System Control Center (SCC). J Clin Microbiol. Jun;47(6) doi: /JCM Epub Apr Performance of the Abbott real-time PCR assay using msp and .
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October 02, ; Accepted Date: October 15, ; Published Date: J Antivir Antiretrovir 2: This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source are credited. Out of paired plasma tested, Comparison of the mean VL with differences of the two methods using the Bland Altman plot showed rough symmetric distribution of the differences, indicating neither method is better than the other for measuring VL.
However, a relative high Of the ND Roche samples, 15 Differences in gene target, test sensitivity, input volume and their abilities to detect different HIV-1 subtypes could potentially explain some of the discordance. This method has now become a standard method for monitoring HIV-infected patients on antiretroviral therapy in the United States.
This trend has lead to the development and approval of a number of diagnostic assays For reviews of these assays, see Constantine and Zhao, These two assays share three common features 1 Additional reduction in the lower limits of detection LOD of HIV-1 RNA from the earlier version; 2 New primers and probes designs for recognition of the different viral subtypes and circulating recombinant forms CRFs ; and 3 Reduction in hand-on time by configuring the test near to full automation.
Table 1 summarizes the assay characteristics of these two assays. Another common feature of these two assays is the use of realtime PCR as their underlying technology for the measurement of HIV- 1 viral load. This gene-target based amplification method is based on the determination of the threshold cycle CT when the amplified product is detected for the first time and the PCR is still in its exponential phase Ciotti et al.
Different from the conventional PCR, an internal probe is added to the detection process, which is an oligo nucleotide with both a fluorescent reporter and a fluorescent quencher dye attached.
Digestion of the probe DNA separates the reporter dye from the quencher dye, making the reporter dye signal detectable.
Comparison of HIV-1 Viral Load between Abbott m2000 and Roche COBAS TaqMan Methods
Detection of the resulting fluorescence collectively provides an immediate real-time quantification of the PCR process. Using the TaqMan analyzer, the sample extraction volume protocol is 0. Four different sample extraction volumes 0. The Abbott method uses real-time platforms with fluorescence detection systems Abbott, b ; Scott et al.
It runs 96 samples per run per day with more if done overnight.
Even though both the Roche and Abbott methods use the realtime PCR technology, the gene targets are different. In addition, their principles in designing primers and probes are also different. While the Roche method uses the standard TaqMan technology, a different and partially double stranded probe is introduced to the Abbott method Finan and Zhao, ; Johanson et al.
Abbott Msp Liquid Handler W/ Mrt PCR | eBay
In this configuration, signal abbottt not created by probe hydrolysis but by separation of the probe from quencher oligonucleotide. Consequently, even though both methods are based on the same principle, due to the differences in their proprietary primer and probe designs, compatibility of these two methods has not been well documented. The objective of this study was to compare results of HIV-1 VL quantification between the 2m000sp methods. This study was approved by the Institutional Research Board under the protocol number of H All blood samples were collected in EDTA tubes.
The Abbott m 0. HIV viral particles were first lysed and an HIV-1 Quantitation Standard QS Armored RNA molecule was added abbotr each sample, which was followed by a series of processes which involves incubation, introduction of magnetic particles, washing to remove unbound particles and elution of nucleic acid NA at elevated temperatures. The Version 2 of the m open mode 0.
This automated system uses magnetic microparticles-based reagents for the purification of nucleic acid from the samples. The general principle for NA extraction is similar to that of the Roche method, i. Finally, the NA was released using an elution buffer. An internal control was added into the samples preparation procedure.
The extracted NA was mixed with the amplification reagents before amplification with the mrt Abbott, a ; Abbott, Following reverse transcription, the RNA: Real-time PCR was used for detection. Dual-labeled fluorescent probes for HIV-1 and HIV-1 Abbott oligonucleotides were used, each labeled with different reporter dyes and a quencher dye. The fluorescence activity was converted into VL yields by the analyzer Roche, The Abbott mrt performed the automated amplification and detection process.
Detection by real-time technology used two probes of different lengths: The fluorescence m2000p were converted into VL measure by the analyzer Abbott, abbotf ; Abbott, All VL values were first transformed into the log10 format. Abgott correlation test was used to measure the overall correlation of the VL between the two methods.
The Bland-Altman analysis was used for the analysis of the concordance of the two methods Bland and Altman, A total of paired plasma samples were tested in the same day by both methods Table 2.
The Abbott method positively identified samples out of with the detectability of Consistently, comparison of the distribution and median values of VL between these two methods also showed similar median VL values but a slight wider distribution by the Roche method than the Abbott method was seen Figure 2.
The difference between these two methods was Log10 ,2000sp. Each data point represents one of the paired quantifi able plasma samples. The best fi t for the regression analysis is indicated by the solid line. The equation of the fi tted line and the Pearson coeffi cient abboht determination are presented on the plot.
Box and Whisker plot for the quantifi able plasma samples. The plot to the left represents the distribution of the VL from the Abbott method assay and the plot to the right represents the distribution of VL from the Roche assay.
The solid line abhott the m200sp indicates the median value and the ends of the whiskers indicate the minimum and maximum values. There were a total of 46 Of ND Roche samples, 15 of them However, comparison of the differences of VL measurements between the two methods by using the Bland Avbott plot showed rough symmetric distribution of the differences and the log differences in Together, these data suggest that neither method is better than the other for measuring VL.
Bland-Altman analysis of the quantitative results.
The vertical axis represenst the VL differences the Abbott method minus the Roche method and the horizontal axis represenst the means of VL. The number of samples within this range was In this study, we have compared VL quantification by the Roche and the Abbott methods side-by-side.
Our data showed that these two methods are essentially indistinguishable with a correlation coefficient of 0. However, a relative significant percentage It is unclear at the moment the source of the discrepancies.
The observed differences could potentially be due to a number of intrinsic differences between these two assays, e. For examples, the Abbott method has been shown to have better detectability of non-B subtypes Geelen et al.
Thus some of the discordant samples could potentially be due to the HIV-1 subtype differences. One way to further evaluate the cause of the observed discrepancies is to determine the HIV-1 subtypes by DNA sequencing.
However, this factor should not be the major contributing factor because a recent surveillance study at the University of Maryland Medical Center showed that about Furthermore, the input plasma volume is different between the two abbott.
In addition, different precision of the methods could also potentially explain some of the discordant results. It should be mentioned that the genetic diversity of HIV-1 subtypes could present a significant challenge in the accurate VL monitoring of HIV-infected patients who carry non-B subtypes Damond et al. Results of this study are unable to evaluate the potential differences between these two assays in this regard.
Other assay performance characteristics such as analytical specificity, linearity, reproducibility, and precision were not evaluated. In conclusion, the two methods showed strong correlation in measuring VL within their testing dynamic range. Various intrinsic factors including the gene target, LOD, input volume and different precision of the methods and variations in HIV-1 subtypes could potentially explain some of the discordant results.
Future work includes increase of the testing population size, determination of the HIV-1 subtypes and DNA sequence analysis of those discrepant samples. The authors would like to thank the staff at the molecular diagnostics laboratory at the University of Maryland Medical Center for their support to ensure comparative testing in realtime.
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