SSM2010
Evaluation of IgG/IgM Immunoblots EUROLine
to confirm Lyme Borreliosis
R. Lienhard1, M. Herzig1, A.-F. Constantin2 and O. Péter2*
1ADMED Microbiologie, La Chaux-de-Fonds et *2ICHV Microbiologie, Sion
Purpose
Diagnosis of Lyme borreliosis is mainly based on clinical features and
serological tests. The two-tier strategy consisting of screening tests
followed by a confirmation test is recommended by EUCALB. We
evaluated new rapid IgG and IgM immunoblot assays for serological
confirmation of Lyme borreliosis.
Material and Methods
Patients’ sera (n=103) have been selected from the serotheque of our
2 laboratories in order to test the main Lyme disease’s stadium: early
localized, early disseminated and late borreliosis.
The selection included 56 erythema migrans (EM), 6 lymphocytoma
(LCB), 19 neuroborreliosis (NB) with specific intrathecal antibody
production, 10 Lyme arthritis (ARTH) and 12 acrodermatitis chronica
atrophicans (ACA). All sera were clinically and serologically defined
cases. Blood donors were selected from the endemic region of
Neuchâtel to measure the seroprevalence. Fifty sera in IgM and 60 in
IgG were examined.
Sera were evaluated by each laboratory with their own sera according to
the kit instructions. Any discrepant result on a serum was retested in the
second laboratory for final interpretation.
Blot interpretation. EUROline (Euroimmun) immunoblots include 3
control bands (poly-Ig, IgM and IgG). The EUROlineScan software was
used to evaluate the results. IgG interpretation criteria are based on VlsE
bands as presented here:
other antigens
VlsE (Bb)
positive
equivocal
negative
>1 or more
+
+
+
1 band
+
+
equiv
no band
+
equiv
neg
Fig1 : Bands presentation
Results were compared with our home-made Western blots (hmWB)
including various genospecies as B. burgdorferi sensu stricto, B. garinii, B.
afzelii and B.valaisiana.
Results
Pos
ARTH IgG
ACA
IgG
10
12
Equiv
0
0
Total
Neg
0
0
N
10
12
hmWestern blot
Pos
10
12
Equiv
0
0
Erythema migrans IgG
Neg
0
0
ARTH IgG
ACA
IgG
IgG
29
10
17
56
15
7
34
EM
IgG
EM
IgM
26
4
26
56
31
3
22
EM
IgM
EM
G+M
38
5
13
56
38
5
13
EM
G+M
NB
IgG
16
1
2
19
16
0
3
NB
IgG
NB
IgM
10
0
9
19
13
1
5
NB
IgM
NB
G+M
17
1
1
19
18
0
1
NB
G+M
LCB
IgG
3
2
1
6
5
0
1
LCB
IgG
IgM
Donor IgG
5
8
47
60
4
2
54
Donor IgG
Donor IgM
5
3
42
50
1
1
48
Donor IgM
Donor G+M
7
8
27
42
3
2
37
Donor G+M
Euroline Euroimmun
EM
IgG
Euroline Euroimmun
Euroimmun
Tab 1 : Results obtained with EUROLine blot tests and the reference
laboratories Western blots on sera of defined clinical symptoms
hm Western blot
pos
lim
nég
pos
12
4
13
29
Euroimmun Sensitivity = 51.8 %
lim
1
2
7
10
Western blot Sensitivity = 26.8 %
nég
2
1
14
17
15
7
34
56
Kappa ratio = 0.30
Neuroborreliosis IgM
hmWestern blot
pos
lim
nég
pos
8
0
2
10
Euroimmun Sensitivity = 52.6 %
lim
0
0
0
0
Western blot Sensitivity = 68.4 %
nég
5
1
3
9
13
1
5
19
Kappa ratio = 0.25
Discussion
IgM
Euroline Euroimmun
The EUROLine IgG immunoblots shows 100% sensitivity in
detecting late borreliosis as expected for ACA and ARTH.
For EM, EUROLine shows better results for IgG with high
sensitivity unusual for confirmation tests at this early stage of the
disease. This is due to the importance of the VlsE antigen in the
interpretation algorithm. EUROLine IgM yields lower sensitivity
which gives a final IgM-IgG sensitivity of 67.8 % equal to the hmWB.
For NB the sensitivity of EUROLine IgM (52.6%) vs hmWB
(68.4%) lowers the good IgG results obtained. In this clinical
situation, IgM test does not add much to the confirmation capability
obtained with IgG blots. It is however of upmost importance to
remind that intrathecal specific antibody test must be applied for
neuroborreliosis diagnosis as immunoblots cannot confirm all the
cases.
EUROLine IgG seroprevalence (8.3%) was equal to hmWB (6.7%)
however a higher number of sera gave undetermined results with
EUROLine (13.3%) vs hmWB (3.3%). Once again IgM parameter
shows lower specificity with prevalence of 10% vs hmWB (2% ), this
is known for OspC and VlsE IgM reactions.
Globally on IgM-IgG EUROLine gave less negative results on blood
donor sera with specificity of 64.3% versus 88% with hmWB
Blood Donors IgM
hmWestern blot
pos
lim
nég
pos
1
0
4
5
Euroimmun Sensitivity = 51.8 %
lim
0
0
3
3
Western blot Sensitivity = 26.8 %
nég
0
1
41
42
1
1
48
50
Kappa ratio = 0.31
Conclusion
The high sensitivity and good results obtained with EUROLine IgG blots
is mainly due to the known high sensitivity and specificity of the VlsE Bb
antigen. IgM results gave lower satisfaction.
The interpretation software gives a convenient report easy to use with a
conventional scanner.
Seroprevalence in blood donors is an interesting parameter allowing to
interpret results with caution.