45 / 152
Abstracts / Journal of Clinical Virology 82S (2016) S1–S142
S41
Abstract no: 292
Presentation at ESCV 2016: Poster 40
Comparison of the recently launched Hologic
Aptima HBV Quant assay with the established
Abbott RealTime HBV assay in viral load
measurement
Robert Ehret
∗
, Andrew Moritz, Marcel Schuetze,
Martin Obermeier
Medical Center for Infectious Diseases, Berlin,
Germany
Background:
Hologic’s Aptima HBV Quant assay is a HBV
DNA quantitative assay based on real-time Transcription Mediated
Amplification (TMA) that runs on the fully automated Panther sys-
tem with random access. A comparison with the Abbott m2000
RealTime assay was performed. Special focus with clinical samples
was put on reproducibility, linearity, sensitivity and performance
in different genotypes.
Methods:
Fresh (
n
= 450), frozen (
n
= 178; 28 with known geno-
type) and diluted (
n
= 618) patient samples spread over the clinical
relevant range were tested. Analytical sensitivity of the Aptima
assay was assessed using dilutions of the AcroMetrix HBV standard
(SKU950150) run in replicates of 10/dilution. Linearity of both
assays was tested by dilution series of patient samples with HBV
genotypes A-F from 8.0 to 2.0 log IU/mL in replicates of 3. Intra-
assay variation was calculated by testing 30 replicates of a clinical
sample in three dilution steps of genotypes A, D and one unspeci-
fied in both systems. Inter-assay variation for the Hologic Aptima
system was assessed testing replicates of clinical samples with
genotype A, D and one unspecified in three dilution steps on 20
different days. Discrepant samples with a difference in viral load
greater 0.5 log IU/ml were retested with the Roche CAP/CTM HBV
assay.
Results:
Aptima HBV Quant assay showed excellent perfor-
mance in high throughput routine. The calculated lower limit of
detection (LLOD) using the Acrometrix standard was 2.02 IU/mL
(plasma, package insert: 5.58 IU/ml). Regression models demon-
strated high concordance between the two assays for all genotypes.
In the correlation analyses for all tested samples the slope was
0.97 with an intercept of 0.17 and
R
2
of 0.94. Bland Altman plots
(Aptima minus RealTime) showed a mean difference of 0.045 with
no change in bias over the complete range from 10 IU/ml up to
650.000.000 IU/ml. Linearity was proofed by serial dilution from
8 log IU/mL to 2 log IU/mL showing no difference between the two
assays. Intra- and inter-assay variation was low and comparable to
RealTime with intra-assay %CV ranging from 1.9% for samples with
a viral load of 3.0 log IU/mL to 16.6% with 1.3 log IU/mL. 44 samples
with a difference of greater than 0.5 log IU/ml were retested. Most
of the discrepant samples showed higher values in the Aptima assay
as compared to the Abbott assay. This was supported by the Roche
CAP/CTM, which also showed higher values than the Abbott assay,
though not as high as the Aptima assay.
Conclusion:
The Aptima HBVQuant assay showed good correla-
tion with Abbott RealTime with the same high sensitivity, linearity
and accuracy for all tested HBV genotypes. In this large comparison
study only a small amount of samples showed discrepant results.
These were mainly in the low to intermediate viral load range and
showed a higher quantification in the Aptima assay, what was sup-
ported by the results of retesting those samples with the Roche
CAP/CTM assay. With random access and time to first result of
about 150min this assay is a major improvement in the viral load
monitoring of HBV infection.
http://dx.doi.org/10.1016/j.jcv.2016.08.080Abstract no: 30
Presentation at ESCV 2016: Poster 41
Comparison of two quantitative detection
assays of cytomegalovirus DNA
Tina Vasehus Madsen
∗
,
Jeannette Kaslund Lilliedal, Xiaohui Chen Nielsen
Department of Clinical Microbiology, Slagelse
Hospital, Denmark
Background:
Cytomegalovirus (CMV) represents the major
infectious cause of birth defects, as well as an important pathogen
for immune-compromised individuals. Quantitative DNA detection
of CMV is critical in the management of transplant patients. In this
study, we compared the performance of two commercially avail-
able CMV quantitative PCR assay in plasma for the diagnosis of CMV
infection.
Materials and methods:
Two commercially available assays:
RealStar
®
CMV PCR Kit 1.0 (altona Diagnostics) and CMV real time
PCR Kit with extraction control (Quidel) were performed accord-
ing to the manufacturers’ instruction on (1) The 1st WHO standard
for CMV (09/162) with 10 folds dilution; (2) QCMD panel 2015;
(3) Thirteen plasma samples collected from Department of Clinical
Microbiology, Vejle Hospital, Denmark with positive CMV PCR.
RealStar
®
CMV PCR Kit 1.0 uses four concentrations for the
standard curve, while the Quidel CMV kit uses only three concen-
trations for the standard curve.
Results:
The 1st WHO standard: The detection limit for
RealStar
®
CMV PCR Kit 1.0 is 5
×
102, while for Quidel CMV kit was
5
×
103. Most of the results from Quidel CMV kit measured CMV
more than 10 times higher than the true value, while quantitation
using RealStar
®
CMV PCR Kit 1.0 is very close to the true value
( Table 1 ).QCMD panel 2015: There were ten samples from two distribu-
tions. Results from RealStar
®
CMV PCR Kit 1.0 were very close to
the expected QCMD results. Results from Quidel CMV kit were all
around one log10 IU/ml higher than the QCMD results
( Table 2 [b]).
Table 1
1st WHO standard
concentration
Altona
Altona
Quidel
Quidel
CT value
IU/ml
CT value
IU/ml
5
×
10
6
22.64
8.2
×
10
6
24.18
1.5
×
10
8
5
×
10
5
26.11
7.2
×
10
5
27.76
1.1
×
10
7
5
×
10
4
30.57
3.1
×
10
4
32.19
4.0
×
10
5
5
×
10
3
33.82
3.2
×
10
3
35.98
2.4
×
10
4
5
×
10
2
37.50
2.4
×
10
2
0
0
5
×
10
1
0
0
0
0
5
×
10
0
0
0
0
0
Table 2
Sample ID Altona Altona
Quiel
Quidel
QCMD
IU/ml
Log
10
IU/ml
IU/ml
Log
10
IU/ml
Log
10
IU/ml
CMV15C1-1
0 0
0 0
2.407
CMV15C1-2 7863 3.896
937745 4.97
3.916
CMV15C1-3 8217 3.915
138175 5.14
3.916
CMV15C1-4 1164 3.066
9358 3.97
2.986
CMV15C1-5 10101 4.004
59300 4.77
3.873
CMV15C2-1 219 2.34
10135 4.01
2.707
CMV15C2-2
0 0
0 0
0
CMV15C2-3 727 2.862
11483 4.06
3.087
CMV15C2-4 110 2.041
0 0
2.151
CMV15C2-5 7959 3.901
124725 5.1
4.107