EVALUATION OF Q-LAMP Iam CMV ASSAY PERFORMANCES FOR THE DETECTION AND
QUANTIFICATION OF CMV-DNA IN CLINICAL SPECIMENS
Giulia Piccirilli*, Angela Chiereghin*, Liliana Gabrielli*, Catherine Mengelle^, Tiziana Lazzarotto*
*O.U. of Microbiology, Laboratory of Virology, Policlinico S. Orsola Malpighi, University of Bologna, Bologna, Italy; ^Laboratory of Virology, Toulouse University Hospital, Toulouse, France.
INTRODUCTION
Although rarely pathogenic in immunocompetent individuals, cytomegalovirus (CMV) causes severe morbidity and mortality in congenitally infected newborns and immunocompromised patients.
AIM
This study evaluates the analytical performance and the clinical utility of a novel molecular test, Q-LAMP Iam CMV (DiaSorin), in the diagnosis of active human CMV infection.
MATERIAL AND METHODS
Figure 1. LIAISON® Ixt/LIAISON® Iam instruments
This study was carried out with the Laboratory of Virology in Toulouse. Here it is shown a part of the project we carried out.
In the first phase, a pre-market evaluation of Q-LAMP Iam CMV analytical performance on LIAISON®Ixt / LIAISON®Iam instruments (Figure 1) was
performed; in particular 8 clinical samples and 35 artificial standards were tested.
In the second phase, 120 clinical samples were processed to evaluate the clinical utility of the Q-LAMP Iam CMV. Fifty urine and 50 plasma samples
were collected from 76 individuals during active CMV infection: 20 urine and 20 plasma from 34 pregnant women with primary/non primary infection;
20 urine from 20 newborns with congenital infection; 10 urine and 10 plasma from 18 immunocompetent patients with symptomatic CMV primary
infection and lastly, 20 plasma from 4 hematopoietic stem cells transplant (HSCT) recipients. Ten urine and 10 plasma samples were collected from
uninfected pregnant women, immunocompetent patients and newborns.
RESULTS
Second phase
First phase
Table 1. Comparison of results obtained by our laboratory
and by DiaSorin Laboratory
Table 2. Q-LAMP Iam CMV results in plasma and/or urine samples from 34 pregnant women
with primary/non primary infection
SEROLOGICAL RESULTS
Id
Expected results
Positive
Negative
WG
Total
IgG
(CMIA)
IgM
(CMIA)
Avidity
VIROLOGICAL
RESULTS
Q-LAMP
(UI/mL)
type of
sample
Id
WG
IgG
(CMIA)
Patients with CMV primary infection
Positive
Obtained
results
Negative
Total
35
0
35
0
8
8
35
8
43
The results from our laboratory were compared with those
obtained in the same samples at the DiaSorin laboratory
(expected results). A good agreement (100%) was
demonstrated (Table 1)
Figure 2. Comparison of viral loads obtained from positive
samples and expected values
VIROLOGICAL
RESULTS
SEROLOGICAL RESULTS
IgM
(CMIA)
Q-LAMP
(UI/mL)
Avidity
Table 3. Q-LAMP Iam CMV results in
urine samples from 20 newborns
with congenital CMV infection
type of
sample
Patients with CMV primary infection
N
plasma
17
19
P
P
Low
N
plasma
N
urine
18
13
P
P
Low
P<8,000
urine
Id
Results Q-LAMP (UI/mL)
1
23,407
2
213,231
3
12,999
4
24,298
5
112,150
1
17
P
P
Low
2
9
P
P
Low
N
plasma
19
12
P
P
Low
P<8,000
urine
3
21
P
P
Low
N
plasma
20
37
P
P
Intermediate
N
plasma
4
23
P
P
Low
N
plasma
21
12
P
P
Intermediate
N
plasma
5
9
P
P
Intermediate
P<8,000
urine
22
10
P
P
ND
N
plasma
6
3,347,886
6
11
P
P
Low
P<8,000
urine
N
plasma
7
29,750
N
plasma
P<8,000
urine
8
162,345
P<8,000
7
35
P
P
Low
23
13
P
P
Low
urine
24
8
P
N
Low
N
plasma
9
15,063
8
15
P
P
Low
N
plasma
25
26
P
BL
Low
P<8,000
urine
10
516,156
9
19
P
P
Low
P<8,000
urine
26
7
P
P
Intermediate
N
urine
11
21,985
10
11
P
P
Intermediate
P<8,000
urine
27
21
P
P
Low
P<8,000
urine
12
23,356
11
10
P
P
Low
N
plasma
28
30
P
P
Low
14,405
urine
P<8,000
urine
29
17
P
P
Low
N
plasma
13
1,008,942
N
plasma
30
15
P
P
Low
P<8,000
urine
14
2,120,740
14,443
urine
15
326,794
16
18,555
12
10
P
P
Low
13
24
P
P
Low
P<8,000
plasma
14
30
N
P
ND
51,471
plasma
31
12
P
P
High
N
plasma
17
90,897
15
30
P
P
ND
N
plasma
32
5
P
BL
High
N
urine
18
5,071,231
P<8,000
plasma
33
8
P
BL
High
P<8,000
urine
19
234,181
P<8,000
urine
34
19
P
P
High
N
urine
20
294,187
16
25
P
P
Low
Patients with non-primary CMV infection
WG: weeks of gestation; CMIA: chemiluminescent microparticle immunoassay; P: positive; N: negative, BL: Border Line, ND: non dosable.
Lower limit quantification of assay: 8,000 UI/mL.
A good correlation (R2=0.80) with the quantitative values
was demonstrated by linear regression (Figure 2)
Figure 3. Comparison of quantitative results obtained and
expected values by Bland-Altman test
CMV-DNA was detected in 20/20
In 18 out of 34 (53%) actively infected pregnant women, plasma and/or urine samples showed (100%) urine samples collected at
Q-LAMP positive results. In particular, 17/30 (57%) were patients with primary and 1/4 (25%) birth from 20 newborns with
non-primary infection (Table 2).
congenital CMV infection (Table 3)
Table 5. Q-LAMP Iam CMV results in plasma and/or
Table 4. Q-LAMP Iam CMV results in plasma
Control population
urine samples from 18 immunocompetent patients
samples from 4 HSCT recipients
Ten urine and 10 plasma samples
SEROLOGICAL RESULTS
VIROLOGICAL RESULTS
Time Post-TX
Q-LAMP
Antiviral
Id
Symptoms
Id
(days)
results (UI/mL)
Therapy
IgG
IgM
Q-LAMP
type of
collected from uninfected pregnant
Avidity
(CMIA)
(CMIA)
results (UI/mL)
sample
35
P<8,000
women (n=7), immunocompetent
oral VGCV:
1
P
P
Low
P<8,000
plasma
42
P<8,000
900 mg
patients (n=9) and newborns (n=4)
1
no
2
P
P
Low
P<8,000
plasma
twice daily
49
P<8,000
resulted negative
(10 days)
2
3
4
53
P<8,000
3
P
P
Low
P<8,000
plasma
18
N
4
P
P
Low
N
urine
25
P<8,000
5
P
P
Low
N
urine
29
P<8,000
6
P
BL
Low
P<8,000
urine
45
29,874
7
P
P
Low
P<8,000
plasma
52
P<8,000
8
P
P
Low
P<8,000
plasma
34
P<8,000
9
P
Low
N
urine
41
P<8,000
10
P
P
Low
P<8,000
plasma
48
P<8,000
11
P
P
Low
P<8,000
plasma
54
P<8,000
12
P
P
Low
P<8,000
plasma
61
P<8,000
P<8,000
urine
68
N
13
P
P
Low
N
plasma
150
N
14
P
P
Low
79,552
urine
155
N
15
p
BL
Low
P<8,000
urine
161
P<8,000
16
P
P
Low
P<8,000
urine
168
P<8,000
17
P
P
Low
N
urine
183
P<8,000
P<8,000
plasma
N
urine
oral VGCV:
900 mg
twice daily
(10 days)
oral VGCV:
900 mg
twice daily (10
days)
intravenous
Foscarnet:
180
mg/kg/days
(16 days)
yes, fever
no
no
VGCV: valganciclovir; Lower limit quantification of assay: 8,000 UI/mL.
The Bland-Altman plot shows that all values obtained were
within 1 log of the expected result, with approximately 70%
within 0.5 log (Figure 3)
18
P
P
Low
VGCV: valganciclovir; CMIA: chemiluminescent microparticle immunoassay
Lower limit quantification of assay: 8,000 UI/mL.
80% (16/20) of plasma samples from 4 HSCT
recipients showed positive results for CMV- In 14/18 (78%) immunocompetent patients primarily
DNA, including one symptomatic patient (Table 4) infected, plasma and/or urine samples showed
positive results for CMV-DNA (Table 5)
CONCLUSION
- Q-LAMP Iam CMV specificity
was 100%;
- The assay identified all
congenitally infected newborns
and actively CMV-infected HSCT
recipients;
- The assay may support the
serological diagnosis in
immunocompetent individuals
and in pregnant women with
active CMV infection.
Acknowledgements
We would like to thank Dr. Giulia Amicarelli, Dr.
Sonia Fantinato and Mr. Paul Eros for their
specialised support