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. METHODOLOGY: Salivary 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/SIGNIFICANCE: Over 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.
- MeSH
- Gene Library * MeSH
- Salivary Proteins and Peptides genetics metabolism MeSH
- Saliva chemistry MeSH
- Transcriptome genetics MeSH
- Triatoma genetics metabolism MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Research Support, N.I.H., Extramural MeSH
- Geographicals
- South America MeSH
BACKGROUND: Salivary proteins of Triatoma infestans elicit humoral immune responses in their vertebrate hosts. These immune responses indicate exposure to triatomines and thus can be a useful epidemiological tool to estimate triatomine infestation. In the present study, we analyzed antibody responses of guinea pigs to salivary antigens of different developmental stages of four T. infestans strains originating from domestic and/or peridomestic habitats in Argentina, Bolivia, Chile and Peru. We aimed to identify developmental stage- and strain-specific salivary antigens as potential markers of T. infestans exposure. METHODOLOGY AND PRINCIPAL FINDINGS: In SDS-PAGE analysis of salivary proteins of T. infestans the banding pattern differed between developmental stages and strains of triatomines. Phenograms constructed from the salivary profiles separated nymphal instars, especially the 5th instar, from adults. To analyze the influence of stage- and strain-specific differences in T. infestans saliva on the antibody response of guinea pigs, twenty-one guinea pigs were exposed to 5th instar nymphs and/or adults of different T. infestans strains. Western blot analyses using sera of exposed guinea pigs revealed stage- and strain-specific variations in the humoral response of animals. In total, 27 and 17 different salivary proteins reacted with guinea pig sera using IgG and IgM antibodies, respectively. Despite all variations of recognized salivary antigens, an antigen of 35 kDa reacted with sera of almost all challenged guinea pigs. CONCLUSION: Salivary antigens are increasingly considered as an epidemiological tool to measure exposure to hematophagous arthropods, but developmental stage- and strain-specific variations in the saliva composition and the respective differences of immunogenicity are often neglected. Thus, the development of a triatomine exposure marker for surveillance studies after triatomine control campaigns requires detailed investigations. Our study resulted in the identification of a potential antigen as useful marker of T. infestans exposure.
- MeSH
- Biomarkers blood MeSH
- Electrophoresis, Polyacrylamide Gel MeSH
- Insect Proteins immunology MeSH
- Bites and Stings immunology MeSH
- Guinea Pigs MeSH
- Proteome analysis MeSH
- Antibodies blood MeSH
- Salivary Proteins and Peptides analysis immunology MeSH
- Triatoma * MeSH
- Blotting, Western MeSH
- Animals MeSH
- Check Tag
- Guinea Pigs MeSH
- Male MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Research Support, N.I.H., Extramural MeSH
- Geographicals
- South America MeSH
Peptides of the adipokinetic hormone (AKH)/red pigment-concentrating hormone (RPCH) family were isolated and sequenced from the retrocerebral corpora cardiaca of four kissing bugs which are all vectors of the protozoan Trypanosoma cruzi responsible for Chagas' disease. The sequence of three novel AKHs were deduced from the multiple MS(N) electrospray mass data: the octapeptide pGlu-Leu-Thr-Phe-Ser-Thr-Asp-Trp amide (denoted Rhopr-AKH) in Rhodnius prolixus and Panstrongylus megistus, the nonapeptide pGlu-Leu-Thr-Phe-Thr-Pro-Asn-Trp-Gly amide (denoted Triin-AKH) in Triatoma infestans and the decapeptide pGlu-Leu-Thr-Phe-Ser-Asp-Gly-Trp-Gly-Asn amide (denoted Dipma-AKH) in Dipetalogaster maxima. The sequences were confirmed by identical behavior of natural and synthetic forms in reversed-phase HPLC and by CID-MS mass spectra. Conspecific injections of a dose of 10 pmol of the respective synthetic peptides resulted in a small but significant increase of the lipid concentration in the hemolymph. These experiments suggest that AKHs in kissing bugs act to regulate lipid metabolism, possibly during dispersal flights which is one of the mechanisms whereby the insects reach new outbreak areas. Copyright © 2012 Elsevier Inc. All rights reserved.
- MeSH
- Hemolymph metabolism MeSH
- Insect Hormones MeSH
- Grasshoppers metabolism drug effects MeSH
- Pyrrolidonecarboxylic Acid * MeSH
- Lipid Metabolism MeSH
- Oligopeptides MeSH
- Panstrongylus * metabolism MeSH
- Rhodnius * metabolism MeSH
- Amino Acid Sequence MeSH
- Sequence Analysis, Protein MeSH
- Triatoma * metabolism MeSH
- Animals MeSH
- Check Tag
- Male MeSH
- Female MeSH
- Animals MeSH
Insecticide-impregnated nets can kill triatomine bugs, but it remains unclear whether they can protect against Chagas disease transmission. In a field trial in Quequeña, Peru, sentinel guinea pigs placed in intervention enclosures covered by deltamethrin-treated nets showed significantly lower antibody responses to saliva of Triatoma infestans compared with animals placed in pre-existing control enclosures. Our results strongly suggest that insecticide-treated nets prevent triatomine bites and can thereby protect against infection with Trypanosoma cruzi. Anti-salivary immunoassays are powerful new tools to evaluate intervention strategies against Chagas disease.
- MeSH
- Chagas Disease prevention & control MeSH
- Insect Control methods MeSH
- Immunoassay MeSH
- Insect Bites and Stings immunology prevention & control MeSH
- Guinea Pigs MeSH
- Parasitology methods MeSH
- Insecticide-Treated Bednets MeSH
- Saliva immunology MeSH
- Triatoma immunology MeSH
- Animals MeSH
- Check Tag
- Guinea Pigs MeSH
- Male MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Research Support, N.I.H., Extramural MeSH
- Geographicals
- Peru MeSH
The genes of ribosomal RNA are the most popular and frequently used markers for bacterial phylogeny and reconstruction of insect-symbiont coevolution. In primary symbionts, such as Buchnera and Wigglesworthia, genome economization leads to the establishment of a single copy of these sequences. In phylogenetic studies, they provide sufficient information and yield phylogenetic trees congruent with host evolution. In contrast, other symbiotic lineages (e.g., the genus Arsenophonus) carry a higher number of rRNA copies in their genomes, which may have serious consequences for phylogenetic inference. In this study, we show that in Arsenophonus triatominarum the degree of heterogeneity can affect reconstruction of phylogenetic relationships and mask possible coevolution between the symbiont and its host. Phylogenetic arrangement of individual rRNA copies was used, together with a calculation of their divergence time, to demonstrate that the incongruent 16S rDNA trees and low nucleotide diversity in the secondary symbiont could be reconciled with the coevolutionary scenario.
- MeSH
- DNA, Bacterial genetics chemistry MeSH
- Enterobacteriaceae genetics isolation & purification classification MeSH
- Financing, Organized MeSH
- Phylogeny MeSH
- DNA, Ribosomal Spacer genetics chemistry MeSH
- Evolution, Molecular MeSH
- Molecular Sequence Data MeSH
- Polymorphism, Genetic MeSH
- RNA, Ribosomal, 16S genetics MeSH
- Base Sequence MeSH
- Sequence Analysis, DNA MeSH
- Sequence Alignment MeSH
- Triatoma microbiology MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- MeSH
- Antigens analysis chemistry immunology MeSH
- Electrophoresis, Polyacrylamide Gel MeSH
- Enzyme-Linked Immunosorbent Assay MeSH
- Insect Bites and Stings immunology MeSH
- Mice MeSH
- Salivary Glands immunology MeSH
- Triatoma immunology MeSH
- Antibody Formation MeSH
- Animals MeSH
- Check Tag
- Male MeSH
- Mice MeSH
- Female MeSH
- Animals MeSH
