Identification and comparative analysis of subolesin/akirin ortholog from Ornithodoros turicata ticks

Abstract

BackgroundSubolesin is an evolutionary conserved molecule in diverse arthropod species that play an important role in the regulation of genes involved in immune responses, blood digestion, reproduction and development. In this study, we have identified a subolesin ortholog from soft ticks Ornithodoros turicata, the vector of the relapsing fever spirochete in the United States.MethodsUninfected fed or unfed O. turicata ticks were used throughout this study. The subolesin mRNA was amplified by reverse transcription polymerase chain reaction (RT-PCR) and sequenced. Quantitative-real time PCR (QRT-PCR) was performed to evaluate subolesin mRNA levels at different O. turicata developmental stages and from salivary glands and gut tissues. Bioinformatics and comparative analysis was performed to predict potential post-translational modifications in O. turicata subolesin amino-acid sequences.ResultsOur study reveals that O. turicata subolesin gene expression is developmentally regulated, where; adult ticks expressed significantly higher levels in comparison to the larvae or nymphal ticks. Expression of subolesin was evident in both unfed and fed ticks and in the salivary glands and midgut tissues. The expression of subolesin transcripts varied in fed ticks with peak levels at day 14 post-feeding. Phylogenetic analysis revealed that O. turicata subolesin showed a high degree of sequence conservation with subolesin’s from other soft and hard ticks. Bioinformatics and comparative analysis predicted that O. turicata subolesin carry three Protein kinase C and one Casein kinase II phosphorylation sites. However, no myristoylation or glycosylation sites were evident in the O. turicata subolesin sequence.ConclusionOur study provides important insights in recognizing subolesin as a conserved potential candidate for the development of a broad-spectrum anti-vector vaccine to control not only ticks but also several other arthropods that transmit diseases to humans and animals.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-015-0749-x) contains supplementary material, which is available to authorized users.

Identification and characterization of a histamine‐binding lipocalin‐like molecule from the relapsing fever tick Ornithodoros turicata

“…We investigated whether or not post‐translational modifications and/or conserved domains were present on Otlip and other salivary lipocalins. The amino acid sequences of Otlip and other lipocalins were individually analysed at PROSITE as described (Sultana et al ., ). Based on the PROSITE analysis, all but three lipocalins analysed in this study carried at least one protein kinase C (PKC) phosphorylation site (Fig.…”

“…Uninfected O. turicata ticks were used throughout this study. Uninfected larvae, nymphs and adult female ticks used in this study were reared as described (Sultana et al ., ). All ticks used in this study were reared from specimens originally donated by Dr J. H. Oliver, Jr, Georgia Southern University, Statesboro, GA, USA.…”

“…Total RNA from freshly fed (24 h after feeding) whole O. turicata ticks was generated using a Qiagen RNA extraction kit (Qiagen, Valencia, CA, USA) following the manufacturer's instructions and as described (Sultana et al ., ). RNA samples were later converted to cDNA using an iSCRIPT cDNA synthesis kit (Bio‐Rad, Hercules, CA, USA).…”

“…The generated cDNA was used as a template for quantifying otlip transcripts using the oligonucleotides 5′‐GTGCCCGGACCAGACTGA‐3′ and 5′‐CGCTTTGCGTTGCTTCATC‐3′. As an internal control and to normalize the amount of template, O. turicata 28S ribosomal RNA transcripts were quantified using oligonucleotides as described (Sultana et al ., ). qRT‐PCR was performed using iQ‐SYBR Green Supermix (Bio‐Rad).…”

“…Total RNA from larvae, nymphs and adult ticks was generated using the RNeasy mini kit (Qiagen) following the manufacturer's instructions and as described (Sultana et al ., ; Neelakanta et al ., ). RNA was converted to cDNA using a Bio‐Rad cDNA synthesis kit (Bio‐Rad).…”