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<p>Introduction</p><p>Ticks are globally recognised as the second most important vectors of infectious diseases, posing significant threats to human and animal health. <i>Haemaphysalis parva</i> (Acari: Ixodidae) is frequently reported infesting humans and domestic animals and has been experimentally demonstrated to transmit <i>Babesia ovis</i>, with field associations to ovine babesiosis during the colder months. It has also been reported to harbour several zoonotic pathogens, including <i>Coxiella burnetii</i>, <i>Francisella tularensis</i>, and various <i>Rickettsia</i> species. Here, we aim to report the complete mitochondrial genome of <i>Haemaphysalis parva</i> (Ixodida: Ixodidae), a zoonotic tick species with significant public health relevance in Türkiye. </p><p>Methods</p><p>For this purpose, we isolated total genomic DNA from <i>H. parva</i> and sequenced using Illumina HiSeq 2000 platform, raw reads were processed, and then the mitogenome was assembled using the Geneious R9 program with “map to reference” and verified via “de novo assembly” options.</p><p>Results and Discussion</p><p>The mitogenome of <i>H. parva</i> is a circular DNA molecule of 14,843&#xa0;bp, comprising the canonical 37 genes (13 PCGs, 22 tRNAs, and 2 rRNAs) and two major non-coding regions (312&#xa0;bp and 304&#xa0;bp). Strand-specific compositional bias revealed a strong A + T enrichment (77.8%) and pervasive negative AT- and GC-skew values, diverging from the typical skew profiles observed in most arthropods and possibly reflecting lineage-specific replication asymmetries. All PCGs exhibited AT-biased codon usage, preferentially encoding hydrophobic amino acids. Several genes (<i>cox1</i>, <i>cytB</i>, <i>nd2</i>, <i>nd6</i>) showed dN/dS ratios &gt; 1, suggesting positive adaptive evolution. Comparative mitogenomic analysis of 27 <i>Haemaphysalis</i> species confirmed overall structural conservation but identified a rearranged <i>nd1</i>–rrnS gene block relative to the <i>Ixodes</i> reference genome. Collinearity and synteny analyses revealed multiple conserved sequence blocks, including a putative humanin-like ORF within the rrnL gene region, indicating potential dual-coding or regulatory elements within non-PCG regions.</p>

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The Complete Mitogenome of Haemaphysalis parva (Arachnida: Ixodidae) and Comparative Mitogenomics of Haemaphysalis Species

  • 期刊论文

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  • 发表日期：

    2026年2月27日

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  • Habeş Bilal Aydemir,
  • Adem Keskin

摘要

Introduction

Ticks are globally recognised as the second most important vectors of infectious diseases, posing significant threats to human and animal health. Haemaphysalis parva (Acari: Ixodidae) is frequently reported infesting humans and domestic animals and has been experimentally demonstrated to transmit Babesia ovis, with field associations to ovine babesiosis during the colder months. It has also been reported to harbour several zoonotic pathogens, including Coxiella burnetii, Francisella tularensis, and various Rickettsia species. Here, we aim to report the complete mitochondrial genome of Haemaphysalis parva (Ixodida: Ixodidae), a zoonotic tick species with significant public health relevance in Türkiye.

Methods

For this purpose, we isolated total genomic DNA from H. parva and sequenced using Illumina HiSeq 2000 platform, raw reads were processed, and then the mitogenome was assembled using the Geneious R9 program with “map to reference” and verified via “de novo assembly” options.

Results and Discussion

The mitogenome of H. parva is a circular DNA molecule of 14,843 bp, comprising the canonical 37 genes (13 PCGs, 22 tRNAs, and 2 rRNAs) and two major non-coding regions (312 bp and 304 bp). Strand-specific compositional bias revealed a strong A + T enrichment (77.8%) and pervasive negative AT- and GC-skew values, diverging from the typical skew profiles observed in most arthropods and possibly reflecting lineage-specific replication asymmetries. All PCGs exhibited AT-biased codon usage, preferentially encoding hydrophobic amino acids. Several genes (cox1, cytB, nd2, nd6) showed dN/dS ratios > 1, suggesting positive adaptive evolution. Comparative mitogenomic analysis of 27 Haemaphysalis species confirmed overall structural conservation but identified a rearranged nd1–rrnS gene block relative to the Ixodes reference genome. Collinearity and synteny analyses revealed multiple conserved sequence blocks, including a putative humanin-like ORF within the rrnL gene region, indicating potential dual-coding or regulatory elements within non-PCG regions.