Intestinal Bacterial Communities of Trypanosome-Infected and Uninfected Glossina palpalis palpalis from Three Human African Trypanomiasis Foci in Cameroon

Abstract

Glossina sp. the tsetse fly that transmits trypanosomes causing the Human or the Animal African Trypanosomiasis (HAT or AAT) can harbor symbiotic bacteria that are known to play a crucial role in the fly's vector competence. We hypothesized that other bacteria could be present, and that some of them could also influence the fly's vector competence. In this context the objectives of our work were: (a) to characterize the bacteria that compose the G. palpalis palpalis midgut bacteriome, (b) to evidence possible bacterial community differences between trypanosome-infected and non-infected fly individuals from a given AAT and HAT focus or from different foci using barcoded Illumina sequencing of the hypervariable V3-V4 region of the 16S rRNA gene. Forty G. p. palpalis flies, either infected by Trypanosoma congolense or uninfected were sampled from three trypanosomiasis foci in Cameroon. A total of 143 OTUs were detected in the midgut samples. Most taxa were identified at the genus level, nearly 50% at the species level; they belonged to 83 genera principally within the phyla Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria. Prominent representatives included Wigglesworthia (the fly's obligate symbiont), Serratia, and Enterobacter hormaechei. Wolbachia was identified for the first time in G. p. palpalis. The average number of bacterial species per tsetse sample was not significantly different regarding the fly infection status, and the hierarchical analysis based on the differences in bacterial community structure did not provide a clear clustering between infected and non-infected flies. Finally, the most important result was the evidence of the overall very large diversity of intestinal bacteria which, except for Wigglesworthia, were unevenly distributed over the sampled flies regardless of their geographic origin and their trypanosome infection status.

The composition and abundance of bacterial communities residing in the gut of Glossina palpalis palpalis captured in two sites of southern Cameroon

“…Therefore, the two foci may share the same eco-climatic features with a Guinean-like climate characteristic of the Congo Basin’s forests. These results are also in agreement with Jacob et al [31], who demonstrated that the bacterial composition of flies collected at the Campo and Bipindi foci were not significantly different. In addition, this result is similar to that of Tchioffo et al [36] and Gimonneau et al [33] who did not show any significant differences between the bacterial flora of the mosquitoes Anopheles coluzzi and Anopheles gambiae in Cameroon.…”

“…This could be due to the fact that it has a more general tropism beyond the intestine and thus can be localized in several other tissues, both extracellularly and intracellularly, including the salivary glands and the hemocoel [38]. However, Sodalis has never been observed to be very abundant in tsetse fly midguts, with maximum reported abundances of around 0.26% [29] and 0.06% [31].…”

“…molecular) methods on G. fuscipes fuscipes fly populations from Kenya [28], G. f. fuscipes , G. m. morsitans and G. pallidipes from Uganda [29], and G. f. fuscipes from Tanzania [30]. In addition, recent work has characterized the bacterial flora of G. palpalis palpalis flies in three foci from Cameroon (Campo, Bipindi and Fontem), demonstrating a great diversity in their bacterial flora [31]. These studies were conducted to examine the bacterial diversity of these flies, but also to identify the impact of certain bacteria (biomarkers) on their biology.…”

Enhancing vector refractoriness to trypanosome infection: achievements, challenges and perspectives

“…Impacts of viral pathology on the tsetse symbionts determined. [ 42 , 47 , 53 , 58 , 59 , 148 – 172 ]; ([ 44 , 54 , 72 , 93 , 173 , 174 ]) (iii). Determine effects of radiation in tsetse, its microbiota and pathogens.…”

“…One of the major achievements of this CRP is the discovery of Spiroplasma as a fourth endosymbiont (in addition to Wigglesworthia , Sodalis , and Wolbachia ) in some wild and laboratory-reared tsetse populations [ 58 , 59 ]. While the function of this bacterium in tsetse is currently unknown, it likely to impact colony fitness.…”