Localized expression and inhibition effect of miR-184 on blood digestion and oviposition in Haemaphysalis longicornis (Acari: Ixodidae)

Muhammad Irfan Malik,Mohsin Nawaz,Muhammad Naveed Anwar,Yongzhi Zhou,Jie Cao,Md Nazrul Islam,Jinlin Zhou,Yanan Wang,Ibrahim A Hassan,Houshuang Zhang

doi:10.1186/s13071-019-3754-7

Muhammad Irfan Malik, Mohsin Nawaz + Show 8 more

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https://doi.org/10.1186/s13071-019-3754-7

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Abstract

BackgroundThe hard tick Haemaphysalis longicornis (Ixodidae) is widely distributed in East Asia, China, Australia and New Zealand. It can transmit many infectious pathogens, including the causative agents of human rickettsiosis, bovine theileriosis, bovine babesiosis and canine babesiosis. Therefore, a greater understanding of H. longicornis biology might aid in the development of more effective control measures against the tick and tick-borne pathogens.MethodsWe analyzed the expression of miR-184 in different developmental stages and various tissues of H. longicornis using real-time PCR (qRT-PCR). Antagomir (Ant-184) was used to knock-down miR-184, whilst Ms-Ant and non-injected ticks were used as the negative and blank controls, respectively. We used online software tools (RNAhybrid and TargetScan) to predict the putative target genes of miR-184.ResultsThe expression of miR-184 was highest in unfed nymphs and lowest in unfed larvae. The tissue distribution of miR-184 showed abundant expression in the midgut. To investigate the probable roles of miR-184, antagomir (Ant-184) was used to knock-down miR-184 (t(4) = 12.32, P = 0.0002). After inhibiting miR-184, other biological factors were examined in each group. The engorged body weight was significantly reduced in the treated group (Ant-184) in contrast to control groups (t(22) = 2.19, P = 0.0388). The mean duration of the egg-laying days was significantly increased (33.5 ± 1.91) and the number of eggs (t(10) = 3.147, P = 0.0137), and egg mass (t(10) = 3.4472, P = 0.0063) were significantly reduced in the treated group. During oviposition, eggs were monitored and in half of the ticks of the Ant-184 group the eggs were completely desiccated, lacked embryo development and did not hatch. We analyzed the expression of Vg proteins (Vg1, Vg2, Vg3) in semi-engorged ticks, engorged ticks, ticks at day 2 after engorgement and egg stage in Ant-184, non-injected and Ms-Ant groups, and found significant variation.ConclusionsThis study provides information on the role of miR-184 in H. longicornis ticks. The data suggest that miR-184 targets Vg proteins and affects blood digestion and oviposition.

Highlights

The hard tick Haemaphysalis longicornis (Ixodidae) is widely distributed in East Asia, China, Australia and New Zealand
The relative expression of miR-184 in various tissues was highest in the midgut and lowest in other tissues (Fig. 1b)
Silencing of miRNA‐184 affects blood digestion and oviposition To study the role of miR-184 in adult female H. longicornis, the sequence-specific antagomir (Ant-184) was used to inhibit miR-184

Summary

Introduction

The hard tick Haemaphysalis longicornis (Ixodidae) is widely distributed in East Asia, China, Australia and New Zealand It can transmit many infectious pathogens, including the causative agents of human rickettsiosis, bovine theileriosis, bovine babesiosis and canine babesiosis. Tick species are widely distributed throughout the world, especially in tropical and subtropical regions [1] They transmit various pathogens of medical and veterinary importance such as bacteria, rickettsiae, protozoans, MicroRNAs (miRNAs) are short non-coding RNAs ranging from 19 to 24 nucleotides in length. They function as modulators of gene expression at the post-transcriptional level by binding, via base-pairing, to their target mRNA. It is expressed in the epidermis, lens and the hatching gland in the zebrafish (Danio rerio) [8]. miR-184 has been observed to be expressed in the brain and testes of mice under the control of MeCP2 [9]

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