Midgut and salivary gland transcriptomes of the arbovirus vector Culicoides sonorensis (Diptera: Ceratopogonidae)

Abstract

Numerous Culicoides spp. are important vectors of livestock or human disease pathogens. Transcriptome information from midguts and salivary glands of adult female Culicoides sonorensis provides new insight into vector biology. Of 1719 expressed sequence tags (ESTs) from adult serum-fed female midguts harvested within 5 h of feeding, twenty-eight clusters of serine proteases were derived. Four clusters encode putative iron binding proteins (FER1, FERL, PXDL1, PXDL2), and two clusters encode metalloendopeptidases (MDP6C, MDP6D) that probably function in bloodmeal catabolism. In addition, a diverse variety of housekeeping cDNAs were identified. Selected midgut protease transcripts were analysed by quantitative real-time PCR (q-PCR): TRY1_115 and MDP6C mRNAs were induced in adult female midguts upon feeding, whereas TRY1_156 and CHYM1 were abundant in midguts both before and immediately after feeding. Of 708 salivary gland ESTs analysed, clusters representing two new classes of protein families were identified: a new class of D7 proteins and a new class of Kunitz-type protease inhibitors. Additional cDNAs representing putative immunomodulatory proteins were also identified: 5' nucleotidases, antigen 5-related proteins, a hyaluronidase, a platelet-activating factor acetylhydrolase, mucins and several immune response cDNAs. Analysis by q-PCR showed that all D7 and Kunitz domain transcripts tested were highly enriched in female heads compared with other tissues and were generally absent from males. The mRNAs of two additional protease inhibitors, TFPI1 and TFPI2, were detected in salivary glands of paraffin-embedded females by in situ hybridization.

An insight into the sialome of the soft tick, Ornithodorus parkeri

“…However, OP-104 also has an RGD motif, indicating it may bind to integrins. Proteins of this family were reported previously in salivary and midgut transcriptome of the hematophagous fly, Culicoides sonorensis (Campbell et al, 2005).…”

The Toxicogenomic Multiverse: Convergent Recruitment of Proteins Into Animal Venoms

“…Kunitz peptides are also a major constituent of ticks and insect hematophagous secretions, inhibiting the function of blood factor Xa (26,161). A number of other double-Kunitz domain proteins have also been identified in the hematophagy gland transcriptome of a nematoceran fly, Culicoides sonorensis (25). Although the functions of these proteins have not been experimentally demonstrated, three of them (named TFPI1-TFPI3) are presumed to be tissue factor pathway inhibitors on the basis of the pronounced antifactor-Xa activity of hematophagous secretion of this species and their apparent orthology (32% identity and 38% similarity at the amino acid sequence level) with the known antifactor-Xa proteins of tick feeding secretion (52).…”

An insight into the sialome of the blood-sucking bug Triatoma infestans, a vector of Chagas’ disease

“…Culicoides are competent vectors of a wide range of economically important pathogens that affect both domestic and wild animals (Mellor et al, 2000). A broad range of genes encoding salivary proteins were characterised from a (SG) cDNA library of C. sonorensis and revealed many proteins involved in antihemostasis, immunomodulation, and digestion (Campbell et al, 2005). In addition to acting as a vector, Culicoides are the primary cause of an extremely pruritic allergic dermatitis, known colloquially as "summer eczema", or "insect bite hypersensitivity" in horses (Anderson, et al, 1993;Kurotaki, et al, 1994).…”