An Updated Insight into the Sialotranscriptome of Triatoma infestans: Developmental Stage and Geographic Variations

Abstract

Background Triatoma infestans is the main vector of Chagas disease in South America. As in all hematophagous arthropods, its saliva contains a complex cocktail that assists blood feeding by preventing platelet aggregation and blood clotting and promoting vasodilation. These salivary components can be immunologically recognized by their vector's hosts and targeted with antibodies that might disrupt blood feeding. These antibodies can be used to detect vector exposure using immunoassays. Antibodies may also contribute to the fast evolution of the salivary cocktail.MethodologySalivary gland cDNA libraries from nymphal and adult T. infestans of breeding colonies originating from different locations (Argentina, Chile, Peru and Bolivia), and cDNA libraries originating from F1 populations of Bolivia, were sequenced using Illumina technology. Coding sequences (CDS) were extracted from the assembled reads, the numbers of reads mapped to these CDS, sequences were functionally annotated and polymorphisms determined.Main findings/SignificanceOver five thousand CDS, mostly full length or near full length, were publicly deposited on GenBank. Transcripts that were over 10-fold overexpressed from different geographical regions, or from different developmental stages were identified. Polymorphisms were mapped to derived coding sequences, and found to vary between developmental instars and geographic origin of the biological material. This expanded sialome database from T. infestans should be of assistance in future proteomic work attempting to identify salivary proteins that might be used as epidemiological markers of vector exposure, or proteins of pharmacological interest.

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

“…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).…”

“…Different from Rhodnius species, salivary proteins of Triatoma and Panstrongylus species in the tribe Triatomini are colorless (Champagne et al, 1995). To identify the variations in blood sucking strategies in kissing bugs, salivary gland transcripts were recently extensively explored in Triatoma species, T. brasiliensis (Santos et al, 2007), T. infestans (Ribeiro et al, 2004a; Assumpção et al, 2008; Schwarz et al, 2014), T. dimidiata (Kato et al, 2010), T. matogrossensis (Assumpção et al, 2012) and T. rubida (Ribeiro et al, 2012). In addition, sialotranscriptome analysis was performed, more recently in a Panstrongylus species , P. megistus (Ribeiro et al, 2015).…”