Species-dependent variation of the gut bacterial communities across Trypanosoma cruzi insect vectors

Abstract

Triatomines (Hemiptera: Reduviidae) are the insect vectors of Trypanosoma cruzi, the causative agent of Chagas disease. The gut bacterial communities affect the development of T. cruzi inside the vector, making the characterization of its composition important in the understanding of infection development. We collected 54 triatomine bugs corresponding to four genera in different departments of Colombia. DNA extraction and PCR were performed to evaluate T. cruzi presence and to determine the discrete typing unit (DTU) of the parasite. PCR products of the bacterial 16S rRNA gene were pooled and sequenced. Resulting reads were denoised and QIIME 2 was used for the identification of amplicon sequence variants (ASVs). Diversity (alpha and beta diversity) and richness analyses, Circos plots, and principal component analysis (PCA) were also performed. The overall T. cruzi infection frequency was 75.9%, with TcI being the predominant DTU. Approximately 500,000 sequences were analyzed and 27 bacterial phyla were identified. The most abundant phyla were Proteobacteria (33.9%), Actinobacteria (32.4%), Firmicutes (19.6%), and Bacteroidetes (7.6%), which together accounted for over 90% of the gut communities identified in this study. Genera were identified for these main bacterial phyla, revealing the presence of important bacteria such as Rhodococcus, Serratia, and Wolbachia. The composition of bacterial phyla in the gut of the insects was significantly different between triatomine species, whereas no significant difference was seen between the state of T. cruzi infection. We suggest further investigation with the evaluation of additional variables and a larger sample size. To our knowledge, this study is the first characterization of the gut bacterial structure of the main triatomine genera in Colombia.

Overview of paratransgenesis as a strategy to control pathogen transmission by insect vectors

“… Rhodnius spp. and Triatoma infestans are the only triatomines in which Wolbachia has been reported in both wild and laboratory populations [ 234 , 249 , 252 ]. …”

Triatomine Raubwanzen als Überträger der Chagas-Krankheit : Verbreitung und Vektor-Pathogen-Interaktion

“…These results are not atypical, as several members of the Corynebacteriales belong to the natural microbiota of triatomine insects, for example Corynebacterium, Dietzia, Nocardia and Gordonia, but also R. rhodnii [75,76,78,96,97]. The reconstructed MAG Rr_FE21 was classified as R. rhodnii, a common mutual symbiont of R. prolixus, that has been described as a member of its microbiome several times [74,79,98,99]. Its extensive appearance in all samples is not surprising, since it has been postulated that the bacteria are important suppliers of vitamin B, a nutrient lacking in the natural diet of obligate blood-sucking insects [100].…”

“…Representatives of the second predominant group in the control group, Enterobacterales, such as Serratia, Arsenophonus and Pectobacterium have also been shown to be members of the core triatomine microbiota [6,74,79,119]. Hence, their presence in all intestinal samples of R. prolixus is not surprising at first.…”

“…Die am häufigsten vertretenen bakteriellen Taxa sind Actinobacteria, Proteobacteria, Firmicutes und Bacteroidetes, wobei sich die Abundanz zwischen den triatominenArten deutlich unterscheiden kann. So sind in Raubwanzen der Gattung Rhodnius vermehrt Bakterien der Ordnung Actinomycetales (Rhodococcus, Gordonia, Ralstonia, Kocuria, Williamsia) und der Abteilung Proteobacteria (Wolbachia, Serratia, nicht-klassifizierte Enterobacteriaceae) zu findenArias-Giraldo et al 2020;. Dabei tritt das ebenfalls zu den Proteobacteria zählende Bakterium Wolbachia ausschließlich in Rhodnius auf.…”

“…Dabei tritt das ebenfalls zu den Proteobacteria zählende Bakterium Wolbachia ausschließlich in Rhodnius auf. Im Gegensatz dazu beherbergen Insekten der Gattung Triatoma eine größere Vielfalt verschiedener Bakterientaxa wie etwa der Klasse der Actinobacteria (Dietzia, Corynebacterium, Mycobacterium, Rhodococcus) und der Bacilli (Bacillus, Staphylococcus), der Gammaproteobacteria (Arsenophonus), der Beta-und Alphaproteobacteria und der BacteroidiaArias-Giraldo et al 2020;. Allerdings zeigt sich auch hier, dass die Mikroorganismenzusammensetzung einzelner Insekten meist von wenigen Taxa dominiert wird, es aber gleichzeitig eine hohe interindividuelle Diversität innerhalb der gleichen Vektorart gibt.…”