Abstract
Lipopolysaccharide (LPS) stimulates the innate immune response in arthropods. In tick vectors, LPS activates expression of immune genes, including those for antibacterial peptides. miRNAs are 21–24 nt non-coding small RNAs that regulate target mRNAs at the post-transcriptional level. However, our understanding of tick innate immunity is limited to a few cellular immune reactions and some characterized immune molecules. Moreover, there is little information on the regulation of the immune system in ticks by miRNA. Therefore, this study aimed to analyze the differential expression of miRNAs in male and female ticks after LPS injection. LPS was injected into male and female Rhipicephalus haemaphysaloides ticks to stimulate immune response, with phosphate buffered saline (PBS)-injected ticks as negative controls. miRNAs from each group were sequenced and analyzed. In the PBS- and LPS-injected female ticks, 11.46 and 12.82 million reads of 18–30 nt were obtained respectively. There were 13.92 and 15.29 million reads of 18–30 nt obtained in the PBS- and LPS-injected male ticks, respectively. Expression of miRNAs in male ticks was greater than that in female ticks. There were 955 and 984 conserved miRNA families in the PBS- and LPS-injected female ticks, respectively, and correspondingly 1684 and 1552 conserved miRNA families in male ticks. Nine novel miRNAs were detected as common miRNAs in two or more tested samples. There were 37 known miRNAs up-regulated >10-fold and 33 down-regulated >10-fold in LPS-injected female ticks; and correspondingly 52 and 59 miRNAs in male ticks. Differential expression of miRNAs in PBS- and LPS-injected samples supports their involvement in the regulation of innate immunity. These data provide an important resource for more detailed functional analysis of miRNAs in this species.
Highlights
Ticks are obligate hematophagous ectoparasites with a global distribution, and have veterinary and medical importance
73 miRNAs in Drosophila melanogaster were studied and thought to be immune-miRNAs, with their potential target genes components of the Toll, Tmd, melanization, C-Jun N-terminal kinase (JNK) and Janus kinase (JAK)/ signal transducer and activator of transcription (STAT) pathways; six of which probably participate in the immune response [7]
Conserved miRNA miR-8 in fat body regulates antimicrobial peptides (AMPs) expression in innate immune homeostasis in Drosophila, while the levels of AMPs such as drosomycin and diptericin are significantly increased in miR-8 null animals in non-pathogen-stimulated conditions [8]
Summary
Ticks are obligate hematophagous ectoparasites with a global distribution, and have veterinary and medical importance They belong to the Phylum Arthropoda, Class Arachnida, Subclass Acari, Order Parasitoformes and Suborder Ixodida [1]. Lipopolysaccharide (LPS) elicits immunerelated gene expression in the fat body of arthropods such as Bombyx mori [5], consistent with it inducing expression of defensin in Haemaphysalis longicornis [6]. How these immune-related molecules are regulated in ticks remains unknown. Etebari and Asgari described miR-8 targeted Serpin 27, which regulates activation of the Toll pathway and prophenoloxidase, which is involved in the melanization response in the insect Plutella xylostella [10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
