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:

Fig1 : Bands presentation

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

Material and Methods

Purpose

Discussion

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.

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.

Results

Tab 1 : Results obtained with EUROLine blot tests and the reference laboratories Western blots on sera of defined clinical symptoms

Euroimmun Sensitivity = 51.8 %

Western blot Sensitivity = 26.8 %

Erythema migrans IgG

Kappa ratio = 0.30

Neuroborreliosis IgM

Blood Donors IgMThe 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

ConclusionThe 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.

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.

SSM2010

 other

antigensVlsE (Bb) >1 or more 1 band no bandpositive + + +equivocal + + equivnegative + equiv neg

Euroimmun Total hmWestern blot

Pos Equiv Neg N Pos Equiv Neg

ARTH IgG 10 0 0 10 10 0 0 ARTH IgG

ACA IgG 12 0 0 12 12 0 0 ACA IgG

EM 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

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

Euroimmun Sensitivity = 52.6 %

Western blot Sensitivity = 68.4 %

Euroimmun Sensitivity = 51.8 %

Western blot Sensitivity = 26.8 %

Kappa ratio = 0.25

Kappa ratio = 0.31