Tick genome assemblies: Overcoming biological limitations through advances in sequencing technologies.

Abstract

Ticks are blood-feeding arthropods with approximately 1000 species; however, only 24 species so far have a genome assembly. These genome assemblies are important resources to advance tick biology and control of tick-associated diseases. Generating tick genome assemblies has been challenging due to their small body size (low DNA input), DNA contamination (from microbiota and host bloodmeals), large genome size (on average 2.4 Gbp for hard ticks) and abundant transposable elements (at least 68% of the assembly for Ixodes species). Advances in sequencing technologies have driven an increasing number of tick assemblies from 2011 to 2025. In total, 70 genome assemblies associated with ticks were identified, and after misclassified genome assemblies were removed, 54 tick genome assemblies remained. These 54 assemblies were reanalysed using QUAST-LG and BUSCO compleasm, providing a comprehensive characterization of these genome assemblies and allowing comparative assessments to be made. Then the impact of biological source material and sequencing platforms on these tick genome assemblies was evaluated. From the 54 tick assemblies, 35 assemblies from 21 species were identified as high-quality assemblies and suitable for downstream analyses. This analysis of tick genome assemblies is an opportunity to provide best-practice recommendations. In particular, future tick genome assemblies should use long-read sequencing platforms and Hi-C scaffolding to improve genomic resources for these unique blood-feeding parasites.