R Gunson on behalf of SCVCG
p1 of 3
Comparison of Scottish labs Adenovirus, CMV and EBV tests
Background
The aim was to compare both the sensitivity and quantitative values of the PCR tests
for adenovirus, CMV and EBV DNA in all 4 Scottish labs, Glasgow, Edinburgh,
Aberdeen and Dundee.
A panel of 5 serial dilutions of adenovirus, CMV and EBV samples was prepared,
tested in Glasgow and distributed to the other 3 Scottish labs (Edinburgh, Aberdeen
and Dundee). These were designed to test the whole process of extraction and
amplification. In addition, one already extracted DNA sample of the three viruses was
also sent. On receiving the returned results, it was apparent that the results of the
samples were lower than expected. Based on this finding we were concerned that the
virus titre might have declined during the transport at room temperature. To determine
this we removed an aliquot from the -80oC freezer and retested this after 36 hrs at
room temperature. On retesting a significant decline in titre of the samples especially
at the bottom end of the range was observed. The titre of the extracted DNA remained
constant. Due to uncertainty about the exact amount of sample decline, we felt unable
to fully interpret the results
Comparison of QCMD results
As an additional QC measure and because we were concerned the results might not be
a true reflection of the loss of titre during transport and storage, we also compared the
most recent QCMD results of all 4 labs.
1. For adenovirus, none of the labs issued a quantitative result but all 4
performed satisfactorily, detecting all samples greater than 1000 copies/ml
(Table 1). Lab 3 failed to detect 1 adenovirus sample of 1,000 copies/ml.
2. For CMV, all labs detected samples greater than 500 copies/ml. For CMV
Glasgow has a quantitative value cut-off of 2,500 copies/ml. The quantitative
results of all 4 labs were comparable to each other and the QCMD value
(within 0.5 log) for values greater than 2,500 copies/ml, the required level of
accurate quantitation (Table 2).
3. For EBV, Glasgow and lab 3 detected all samples. Lab 2 failed to detect one
sample at 3,500, whilst Lab 4 failed to detect 1 sample at 700. For EBV
Glasgow has a quantitative value cut-off of 5,000 copies/ml. The quantitative
results of Glasgow, lab 2 and lab 3 were comparable to each other and the
QCMD value (within 0.3 log). Lab 4 quantitated 0.5 - 1.0 log lower than the
other labs and QCMD (Table 3).
Conclusions
All 4 Scottish labs performed equivalently and satisfactorily for adenovirus and CMV
detection and for CMV quantitation. All 4 Scottish labs performed equivalently and
satisfactorily for EBV detection. Glasgow, Lab 2 and Lab 3 performed equivalently
and satisfactorily for EBV quantitation; Lab 4 EBV 0.5 – 1 log lower than the other
labs and QCMD.
R Gunson on behalf of SCVCG
p2 of 3
Table 1: Comparison of Scottish labs adenovirus QCMD results
QCMD
number
ADV11-01
ADV11-02
ADV11-03
ADV11-04
ADV11-05
ADV11-06
ADV11-07
ADV11-08
QCMD log
2.99
3.13
2.43
neg
4.03
4.14
3.87
3.1
Glasgow
log
pos
pos
pos
neg
pos
pos
pos
pos
Lab 2 log
pos
pos
pos
neg
pos
pos
pos
pos
Lab 3 log
neg
pos
pos
neg
pos
pos
pos
pos
Lab 4 log
pos
pos
pos
neg
pos
pos
pos
pos
Table 2: Comparison of Scottish labs CMV QCMD results
QCMD
number
QCMD
log/ml
Glasgow
log/ml
Lab 2 log
Lab 3 log
Lab 4 log
CMV12-01
CMV12-02
CMV12-03
CMV12-04
CMV12-05
CMV12-06
CMV12-07
CMV12-08
CMV12-09
CMV12-10
4.3
3.74
2.24
2.08
2.91
3.3
3.33
neg
3.67
2.73
3.97
3.38
1.12
neg
2.86
2.9
2.8
neg
3.29
2.72
4.12
3.67
neg
pos
2.96
3.12
3
neg
3.49
2.82
4.33
4.11
2.33
2.56
3.41
3.22
3.33
neg
3.75
2.95
4
4.04
neg
neg
3
pos
3.34
neg
3.76
pos
R Gunson on behalf of SCVCG
p3 of 3
Table 3: Comparison of Scottish labs EBV QCMD results
QCMD
number
EBV12-01
EBV12-02
EBV12-03
EBV12-04
EBV12-05
EBV12-06
EBV12-07
EBV12-08
EBV12-09
EBV12-10
QCMD log
2.76
3.8
5.21
4.82
4.33
4.49
4.79
3.5
4.3
neg
Glasgow
log
2.92
4.15
5.54
4.93
4.63
4.88
4.96
3.89
3.43
neg
Lab 2 log
pos
4.18
5.55
5.12
4.66
4.76
4.73
neg
3.57
neg
Lab 3 log
2.99
4.49
5.64
5.21
4.96
5.04
5.27
3.92
3.77
neg
Lab 4 log
neg
3.18
4.76
4.32
3.79
3.87
4.38
pos
pos
neg