Enabling metagenomic surveillance for bacterial tick-borne pathogens using nanopore sequencing with adaptive sampling

Technological and computational advancements in the fields of genomics and bioinformatics are providing exciting new opportunities for pathogen discovery and surveillance. In particular, single-molecule nucleotide sequence data originating from Oxford Nanopore Technologies (ONT) sequencing platforms can be bioinformatically leveraged, in real-time, for enhanced biosurveillance of a vast array of zoonoses. The recently released nanopore adaptive sampling (NAS) pipeline facilitates immediate mapping of individual nucleotide molecules (i.e., DNA, cDNA, and RNA) to a given reference as each molecule is sequenced. User-defined thresholds then allow for the retention or rejection of specific molecules, informed by the real-time reference mapping results, as they are physically passing through a given sequencing nanopore. Here, we show how NAS can be used to selectively sequence entire genomes of bacterial tick-borne pathogens circulating in wild populations of the blacklegged tick vector, Ixodes scapularis. The NAS method provided a two-fold increase in targeted pathogen sequences, successfully enriching for Borrelia (Borreliella) burgdorferi s.s.; Borrelia (Borrelia) miyamotoi; Anaplasma phagocytophilum; and Ehrlichia muris eauclairensis genomic DNA within our I. scapularis samples. Our results indicate that NAS has strong potential for real-time sequence-based pathogen surveillance.