Characterization of the microbiota in the guts of Triatoma brasiliensis and Triatoma pseudomaculata infected by Trypanosoma cruzi in natural conditions using culture independent methods

Abstract

BackgroundChagas disease is caused by Trypanosoma cruzi, which is transmitted by triatomine vectors. The northeastern region of Brazil is endemic for Chagas disease and has the largest diversity of triatomine species. T. cruzi development in its triatomine vector depends on diverse factors, including the composition of bacterial gut microbiota.MethodsWe characterized the triatomines captured in the municipality of Russas (Ceará) by sequencing the cytochrome c oxidase subunit I (COI) gene. The composition of the bacterial community in the gut of peridomestic Triatoma brasiliensis and Triatoma pseudomaculata was investigated using culture independent methods based on the amplification of the 16S rRNA gene by polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE), DNA fragment cloning, Sanger sequencing and 454 pyrosequencing. Additionally, we identified TcI and TcII types of T. cruzi by sequencing amplicons from the gut metagenomic DNA with primers for the mini-exon gene.ResultsTriatomines collected in the peridomestic ecotopes were diagnosed as T. pseudomaculata and T. brasiliensis by comparing their COI sequence with GenBank. The rate of infection by T. cruzi in adult triatomines reached 80% for T. pseudomaculata and 90% for T. brasiliensis. According to the DNA sequences from the DGGE bands, the triatomine gut microbiota was primarily composed of Proteobacteria and Actinobacteria. However, Firmicutes and Bacteroidetes were also detected, although in much lower proportions. Serratia was the main genus, as it was encountered in all samples analyzed by DGGE and 454 pyrosequencing. Members of Corynebacterinae, a suborder of the Actinomycetales, formed the next most important group. The cloning and sequencing of full-length 16S rRNA genes confirmed the presence of Serratia marcescens, Dietzia sp., Gordonia terrae, Corynebacterium stationis and Corynebacterium glutamicum.ConclusionsThe study of the bacterial microbiota in the triatomine gut has gained increased attention because of the possible role it may play in the epidemiology of Chagas disease by competing with T. cruzi. Culture independent methods have shown that the bacterial composition of the microbiota in the guts of peridomestic triatomines is made up by only few bacterial species.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-015-0836-z) contains supplementary material, which is available to authorized users.

Triatomine bugs, their microbiota and Trypanosoma cruzi: asymmetric responses of bacteria to an infected blood meal

“…Some differences in the taxonomic composition of triatomine gut bacterial communities were found in our study, in comparison with previous results obtained with non-culture- [19, 20] and culture-based methods (reviewed in great extension by Vallejo et al [32]). A significant absence in our samples is Serratia , a genus of bacteria that have trypanolytic activity on specific T. cruzi strains [12].…”

“…Moreover, the ability of some T. cruzi strains to develop in certain vector species depends on the intrinsic qualities of either the parasite or the insect vector, as well as the resident host gut microbiota [18]. Previous studies using non-culturing based methods [19, 20] identified some triatomine gut microbiota characteristics: first, its diversity within each host is low with only one or few genera being dominant; secondly, some bacterial genera appear to be specific to certain triatomine hosts, i.e. Rhodococcus to Rhodnius and Arsenophonus to Triatoma ; finally, lab-reared insects lose part of the original microbiota diversity but conserve most of the bacterial groups found in their wild counterparts.…”

Cultivable Bacterial Diversity in the Gut of the Chagas Disease Vector Triatoma dimidiata: Identification of Possible Bacterial Candidates for a Paratransgenesis Approach

“…This finding is in line with previous studies of other insects (Rani et al, 2009;Belda et al, 2011;Rinke et al, 2011;Gumiel et al, 2015). The potential explanation behind this observation is that insects reared under laboratory conditions are not under the same selective pressure as wild specimens.…”

“…Previous studies have reported a low diversity of bacteria associated with the microbiota of triatomine insects in comparison to other insect groups (Vallejo et al, 2009;da Mota et al, 2012;Gumiel et al, 2015). Our results agree with this observation since we found only 14 different 16S rRNA sequences among all field collecting sites, laboratory specimens, and life stages of the insects.…”

Characteristics of Triatomine infestation and natural Trypanosoma cruzi infection in the State of Rio Grande do Norte, Brazil

“…TcI has also been identifi ed in T. pseudomaculata and R. nasutus in the peridomicile and natural environments of fi ve State of Ceará peri-urban and urban localities (73) . Therein, high TcI and TcII infection rates were detected in peridomestic T. brasiliensis and T. pseudomaculata, respectively (74) . TcI has been most frequently identifi ed in triatomines of the State of Mato Grosso do Sul (75) .…”