Differences in the amino acid sequences of the P66 surface-exposed loop regions in various isolates of Borrelia afzelii

The intraspecific differences between the amino acid sequences of the P66 protein surface-exposed loop region (89 amino acids) in 45 isolates of 7 different allelic variants of B. afzelii were studied. It was established that this group includes 6 phenotypically different variants, two of which have different amino acid substitutions in the surface-exposed loop region, as well as different mutations in the putative monoclonal antibody H1337 binding site. The level of similarity between these phenotypic variants was 96.66–98.88%. It has been shown that, in a natural locus, up to three different amino acid variants of the studied P66 protein surface-exposed loop region can circulate simultaneously.