Background:
The aim of this study was to evaluate the dynamics of changes in IgG anti-C6VlsE concentration in patients treated for Lyme borreliosis in relation to clinical manifestations of the disease.

Material and methods:
The study group consisted of 20 patients from Ternopil and surrounding areas (Western Ukraine) with clinical symptoms of Lyme borreliosis. IgG anti-C6VlsE was measured three times: before starting the patients on antibiotic therapy, immediately after its completion and 3-4 months after the end of antibiotic therapy.

Results:
In 40% of the patients the IgG anti-C6VlsE concentration decreased 3-4 months after the treatment, but only in half of them it was associated with elimination of symptoms. 60% of patients did not show any tendency to decrease in IgG anti-C6VlsE concentrations after 3-4 months after the treatment, and 25% of patients in this group had an improvement in health condition.

Conclusions:
It cannot be excluded that IgG anti-C6VlsE may be important in the serological evaluation of the efficacy of Lyme borreliosis treatment, especially in early stage patients. However, this requires further research, which should be extended to a larger group of patients. It is also important that the assessment of anti-C6VlsE antibody concentration should be performed additionally for a period longer than 4 months from the end of antibiotic therapy.