Point-of-care detection of Borrelia antibodies using Sofia 2 Lyme+ FIA: Comparison of finger-prick whole blood assay versus testing in serum or plasma

Lyme disease is a systemic, tick-borne disease caused by the bacterium Borrelia
burgdorferi. Diagnostic testing consists of serological assays in which
antibodies against different Borrelia burgdorferi strains are detected. Sofia
Lyme fluorescent immunoassay (FIA) has been developed in the US as a rapid
point-of-care assay, in which anti-Borrelia IgG and IgM are measured
simultaneously within 10 minutes in plasma or serum specimens. The Sofia Lyme
FIA has been adapted for the European setting (EU version: Sofia 2 Lyme+),
where additional pathogenic Borrelia strains are present. To improve the
usability of Sofia 2 Lyme+ in near-patient environments, the assay needs to be
adapted to antibody detection in finger-stick whole blood specimens. The
hypothesis of the current study is that performance of the Sofia 2 Lyme+ whole
blood (WB) FIA is not inferior compared to testing in serum or plasma
specimens.

This study consists of two subsequent phases, with different objectives. The
first phase includes a technical, explorative part with the objective of
determining appropriate cut-off values and incubation times for the Sofia 2
Lyme+ WB FIA compared to Sofia 2 Lyme+ testing with serum/plasma. Based on a
comparable study that was done is the US for the American version of Sofia
Lyme, the expectation is that the sample incubation time will be somewhat
longer for testing in whole blood (15 minutes instead of 10 minutes in the US)
and that cut-off values will have to adjusted for both IgG and IgM antibody
testing.

When the required technical adjustments have been implemented for the Sofia 2
Lyme+ WB FIA, the second phase of this study will start. The objective of this
part is to assess the performance of the whole blood assay: sensitivity and
specificity complared to the CE-marked Sofia 2 Lyme+ assay with serum/plasma.
In this study, we consider a sensitivity and specificity of 95% acceptable for
the whole blood assay. The whole blood assay should not lead to more than 5%
false-positives or 5% false-negatives compared to testing in serum/plasma.
Based on the previous comparison in the US between testing in whole blood
versus serum/plasma we expect that Sofia 2 Lyme+ WB FIA is non-inferior to
Sofia 2 Lyme+ testing with serum/plasma, when technical parameters of the test
have been correctly adapted.

Matched finger-stick whole blood, serum, and plasma specimens will be collected
to compare Sofia 2 Lyme+ WB test results to Sofia 2 Lyme+ (serum/plasma
testing) and comparator method results (i.e. standard ELISA and immunoblots).
The study will consist of two phases, starting with an exploratory phase to
determine cut-off values and incubation time for the WB assay. Next,
performance of the adapted WB assay will be validated in the second phase of
the study, in which new matched specimens will be collected and tested.

Venipunctures and finger-stick blood draws are performed by trained
phlebotomists and pose a negligible risk. Participation will require a one-time
visit of max. 20 minutes. There are no other procedures or follow-up after the
specimens are obtained.