D3396: Comparison of Borrelia burgdorferi sensu stricto strain diversity detected by next generation sequencing directly in field-collected Ixodes scapularis and in cultures derived from field-collected ticks

Lyme disease, caused primarily by Borrelia burgdorferi sensu stricto (Bbss), is the most commonly reported vector-borne disease in the United States. Bbss strain diversity is considerable within the primary vector, Ixodes scapularis Say (Acari: Ixodidae). Genetic variation has been associated with differences in transmissibility and pathogenecity of Bbss. Advances in molecular detection, including the use of next generation sequencing, has improved the sensitivity and specificity of pathogen detection assays compared with conventional methods. However, Bbss strain diversity may differ across specimen types tested. Here, we describe the diversity of Bbss strains detected in host-seeking I. scapularis adults collected from northern New York. We compare the diversity of strains detected directly from field-collected ticks with strain diversity observed in Bbss cultures derived from paired samples of ticks using a targeted amplicon next generation sequencing assay. Five unique Bbss strains were identified in the ticks and tick cultures: B31, B331, N40, MM1, and SI-1. However, Bbss strain diversity was higher in samples derived directly from the ticks compared to cultures grown in BSK-II media; strain diversity decreased through successive passages, with usually one or two strains persisting by the last passage. Although cultures can be invaluable to research, this study highlights declines in strain diversity that may occur through bottlenecks associated with culture and successive passage of cultures.