Immunogenic Salivary Proteins of Triatoma infestans: Development of a Recombinant Antigen for the Detection of Low-Level Infestation of Triatomines

Chagas disease, caused by Trypanosoma cruzi, is a neglected disease with 20 million people at risk in Latin America. The main control strategies are based on insecticide spraying to eliminate the domestic vectors, the most effective of which is Triatoma infestans. This approach has been very successful in some areas. However, there is a constant risk of recrudescence in once-endemic regions resulting from the re-establishment of T. infestans and the invasion of other triatomine species. To detect low-level infestations of triatomines after insecticide spraying, we have developed a new epidemiological tool based on host responses against salivary antigens of T. infestans. We identified and synthesized a highly immunogenic salivary protein. This protein was used successfully to detect differences in the infestation level of T. infestans of households in Bolivia and the exposure to other triatomine species. The development of such an exposure marker to detect low-level infestation may also be a useful tool for other disease vectors

Chagas disease in Bolivia: a brief review of the urban phenomena

Chagas disease is a major public health problem in Latin America. At present, Bolivia has the highest rate of vector and congenital transmission, and the old rural profile of the disease is changing rapidly into urban. Recent epidemiologic data indicates that all the capital cities of the 9 Bolivian departments still have new cases of Chagas disease in children under fifteen years. However, good news came from Bolivia: the Chagas control program has reduced importantly the rate of infection. We present a brief review on the Chagas disease literature concerning Bolivia and discuss the present problems and challenges in epidemiology, vector distribution, clinical management, congenital transmission and drug treatment.La enfermedad de Chagas es un problema grave de salud pública en América Latina. Actualmente, Bolivia presenta la tasa más alta de transmisión vectorial y congénita; el perfil rural antiguo de la enfermedad está cambiando rápidamente a la urbanización. Datos epidemiológicos recientes indican que todas las capitales de los nueve departamentos bolivianos arrojan todavía casos nuevos de la enfermedad de Chagas en niños menores de 15 años. Sin embargo, el programa de control de Chagas en Bolivia ha reducido la tasa de infección de manera significativa. Presentamos aquí una revisión de la literatura sobre la enfermedad de Chagas en Bolivia; discutimos también los problemas y los desafíos actuales en epidemiología, distribución de vectores, manejo clínico, transmisión congénita y tratamiento farmacológico

An Updated Insight into the Sialotranscriptome of <i>Triatoma infestans</i>: Developmental Stage and Geographic Variations

<div><p>Background</p><p><i>Triatoma infestans</i> 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.</p><p>Methodology</p><p>Salivary gland cDNA libraries from nymphal and adult <i>T. infestans</i> 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.</p><p>Main findings/Significance</p><p>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 <i>T. infestans</i> 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.</p></div

Classification of coding sequences at least 10× overexpressed in nymphal libraries when compared to adult libraries.

<p>Classification of coding sequences at least 10× overexpressed in nymphal libraries when compared to adult libraries.</p

Transcripts found overexpressed (>10 fold) on Argentinian population.

<p>Transcripts found overexpressed (>10 fold) on Argentinian population.</p

Polymorphic sites allowing differences between ITS-2 and ITS1 rDNA haplotypes of <i>T. infestans</i> samples analysed from Bolivia, Peru, Chile and Argentina and those available in GenBank.

<p>*haplotypes from present paper; variable positions = numbers (to be read in vertical) refer to variable positions obtained in the ITS-2 and ITS-1 alignments obtained with MEGA 6.0; symbols: identical positions = .; indel = -; indel position in 3′ end of the alignment = not sequenced. Haplotypes that seem to be identical: T.inf-GT1 = T.inf-ITS2Hap1; T.inf-GT2 = T.inf-ITS2Hap4; T.inf-GT3 = ITInf72.</p><p>Polymorphic sites allowing differences between ITS-2 and ITS1 rDNA haplotypes of <i>T. infestans</i> samples analysed from Bolivia, Peru, Chile and Argentina and those available in GenBank.</p

Polymorphism values derived from adult and nymphal coding sequences from different colonies.

<p>For each colony (Argentina, Chile, Peru, Bolivian colony and Bolivian F1) synonymous and non-synonymous single nucleotide polymorphisms were determined as indicated in the <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003372#s2" target="_blank">methods</a> section. The bars represent the average and SE of 5,391 polymorphic CDS.</p

RNAseq metadata from <i>T. infestans</i> sialotranscriptomes following trimming of low quality (<10) ends and rejection of average quality <20.

<p><b>*</b>Arg = Argentina. BolCol = Bolivian colony. BolNat = Bolivian F1 strain. The suffix –A stands for adult, -N for nymphal libraries.</p><p><b>**</b>See supplemental <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003372#pntd.0003372.s002" target="_blank">table S1</a> for description of strains.</p><p>RNAseq metadata from <i>T. infestans</i> sialotranscriptomes following trimming of low quality (<10) ends and rejection of average quality <20.</p

Transcripts found overexpressed (>10 fold) on Chilean population.

<p>Transcripts found overexpressed (>10 fold) on Chilean population.</p

Polymorphisms detected on the <i>Triatoma infestans</i> sialotranscriptome according to functional class.

<p><b>*</b>Number of synonymous or non-synonymous polymorphisms per 100 codons.</p><p>Polymorphisms detected on the <i>Triatoma infestans</i> sialotranscriptome according to functional class.</p