A Deep Insight into the Sialome of Rhodnius neglectus, a Vector of Chagas Disease

Abstract

BackgroundTriatomines are hematophagous insects that act as vectors of Chagas disease. Rhodnius neglectus is one of these kissing bugs found, contributing to the transmission of this American trypanosomiasis. The saliva of hematophagous arthropods contains bioactive molecules responsible for counteracting host haemostatic, inflammatory, and immune responses.Methods/Principal FindingsNext generation sequencing and mass spectrometry-based protein identification were performed to investigate the content of triatomine R. neglectus saliva. We deposited 4,230 coding DNA sequences (CDS) in GenBank. A set of 636 CDS of proteins of putative secretory nature was extracted from the assembled reads, 73 of them confirmed by proteomic analysis. The sialome of R. neglectus was characterized and serine protease transcripts detected. The presence of ubiquitous protein families was revealed, including lipocalins, serine protease inhibitors, and antigen-5. Metalloproteases, disintegrins, and odorant binding protein families were less abundant.Conclusions/SignificanceThe data presented improve our understanding of hematophagous arthropod sialomes, and aid in understanding hematophagy and the complex interplay among vectors and their vertebrate hosts.

Salivary gland transcripts of the kissing bug, Panstrongylus chinai , a vector of Chagas disease

“…The putative secreted category comprised 437 clones (56.5%) in 64 contigs. High ratios of transcripts encoding secreted proteins were reported in other triatomine bugs (Ribeiro et al, 2004a, 2012, 2015; Santos et al, 2007; Assumpção et al, 2008, 2011, 2012; Kato et al, 2010; Santiago et al, 2016). The housekeeping category had 155 clones (20.1%) in 111 contigs, and the category of “unknowns” comprised 181 clones (23.4%) in 127 contigs.…”

“…Kazal-type serine pro-tease inhibitors identified in mosquito and leech saliva and in the midgut of kissing bugs have been characterized to work as anticoagulants during blood feeding (Friedrich et al, 1993; Campos et al, 2002; Nowak and Schrör, 2007; Santos et al, 2007; Rimphanitchayakit and Tassanakajon, 2010; Watanabe et al, 2010, 2011). Although homologous proteins to Kazal-type serine protease inhibitors have been identified in the saliva of kissing bugs (Santos et al, 2007; Assumpção et al, 2008, 2012; Schwarz et al, 2014; Ribeiro et al, 2015; Santiago et al, 2016), their bioactivities have not yet been characterized. In the P. chinai salivary gland transcripts coding for secretory proteins, a higher ratio of this molecule (7.8%) was identified when compared to other triatomine bugs (0.5–2.8%) (Santos et al, 2007; Assumpção et al, 2008, 2012; Schwarz et al, 2014; Ribeiro et al, 2015; Santiago et al, 2016), suggesting its important role in blood feeding in this species.…”

“…Although homologous proteins to Kazal-type serine protease inhibitors have been identified in the saliva of kissing bugs (Santos et al, 2007; Assumpção et al, 2008, 2012; Schwarz et al, 2014; Ribeiro et al, 2015; Santiago et al, 2016), their bioactivities have not yet been characterized. In the P. chinai salivary gland transcripts coding for secretory proteins, a higher ratio of this molecule (7.8%) was identified when compared to other triatomine bugs (0.5–2.8%) (Santos et al, 2007; Assumpção et al, 2008, 2012; Schwarz et al, 2014; Ribeiro et al, 2015; Santiago et al, 2016), suggesting its important role in blood feeding in this species. The sequence of Pc76 was truncated in the 5′ region.…”

“…The sequence of Pc292 was truncated in the 5′ region. Although the role of salivary IP5Ps remains unclear, the enzyme is well-conserved in kissing bugs, suggesting that it plays an important role in the blood sucking process of this insect (Ribeiro et al, 2004a, 2012, 2015; Andersen and Ribeiro, 2006; Santos et al, 2007; Assumpção et al, 2008, 2011, 2012; Kato et al, 2010; Schwarz et al, 2014; Santiago et al, 2016). In the alignment of the encoding proteins with IP5P-like protein identified in T. infestans saliva, two cysteine residues were located at the corresponding positions in all molecules (Fig.…”

“…This family of proteins belongs to the cysteine-rich secretory proteins (CRISPs) that are related to venom allergens in social wasps and ants (Lu et al, 1993; Hoffman, 1993; King and Spangfort, 2000). Transcripts coding for this family of protein have been identified in the salivary glands of blood sucking insects including kissing bugs (Ribeiro et al, 2004a, 2012, 2015; Santos et al, 2007; Assumpção et al, 2008, 2011, 2012; Kato et al, 2010; Schwarz et al, 2014; Santiago et al, 2016). Salivary antigen 5 family proteins form kissing bugs were shown to inhibit collagen-induced platelet aggregation and neutrophil oxidative burst (Assumpção et al, 2013).…”