INTERTRYP, Institut de Recherche pour le Développement, University of Montpellier, Montpellier, France; Faculty of Science, University of Yaoundé I, P.O. Box 812, Yaoundé, Cameroon.
Faculty of Science, University of Yaoundé I, P.O. Box 812, Yaoundé, Cameroon.
Infect Genet Evol. 2021 Jun;90:104763. doi: 10.1016/j.meegid.2021.104763. Epub 2021 Feb 8.
The purpose of this study was to investigate factors involved in vector competence by analyzing whether the diversity and relative abundance of the different bacterial genera inhabiting the fly's gut could be associated with its trypanosome infection status. This was investigated on 160 randomly selected G. p. palpalis flies - 80 trypanosome-infected, 80 uninfected - collected in 5 villages of the Campo trypanosomiasis focus in South Cameroon. Trypanosome species were identified using specific primers, and the V4 region of the 16S rRNA gene of bacteria was targeted for metabarcoding analysis in order to identify the bacteria and determine microbiome composition. A total of 261 bacterial genera were identified of which only 114 crossed two barriers: a threshold of 0.01% relative abundance and the presence at least in 5 flies. The secondary symbiont Sodalis glossinidius was identified in 50% of the flies but it was not considered since its relative abundance was much lower than the 0.01% relative abundance threshold. The primary symbiont Wigglesworthia displayed 87% relative abundance, the remaining 13% were prominently constituted by the genera Spiroplasma, Tediphilus, Acinetobacter and Pseudomonas. Despite a large diversity in bacterial genera and in their abundance observed in micobiome composition, the statistical analyzes of the 160 tsetse flies showed an association with flies' infection status and the sampling sites. Furthermore, tsetse flies harboring Trypanosoma congolense Savanah type displayed a different composition of bacterial flora compared to uninfected flies. In addition, our study revealed that 36 bacterial genera were present only in uninfected flies, which could therefore suggest a possible involvement in flies' refractoriness; with the exception of Cupriavidus, they were however of low relative abundance. Some genera, including Acinetobacter, Cutibacterium, Pseudomonas and Tepidiphilus, although present both in infected and uninfected flies, were found to be associated with uninfected status of tsetse flies. Hence their effective role deserves to be further evaluated in order to determine whether some of them could become targets for tsetse control of fly vector competence and consequently for the control of the disease. Finally, when comparing the bacterial genera identified in tsetse flies collected during 4 epidemiological surveys, 39 genera were found to be common to flies from at least 2 sampling campaigns.
本研究旨在通过分析栖息在蝇肠道中的不同细菌属的多样性和相对丰度是否与它们的锥虫感染状态相关，来研究媒介效能的相关因素。在喀麦隆南部坎波锥虫病疫区的 5 个村庄中，随机选择了 160 只 G. p. palpalis 苍蝇进行研究，其中 80 只为锥虫感染，80 只为未感染。使用特定引物鉴定锥虫种类，并针对细菌 16S rRNA 基因的 V4 区进行代谢组学分析，以鉴定细菌并确定微生物组组成。共鉴定出 261 个细菌属，其中只有 114 个细菌属跨越了两个障碍：相对丰度阈值为 0.01%，且至少存在于 5 只苍蝇中。共生菌 Sodalis glossinidius 在 50%的苍蝇中被鉴定出来，但由于其相对丰度远低于 0.01%的相对丰度阈值，因此未被考虑。共生菌 Wigglesworthia 的相对丰度为 87%，其余 13%主要由 Spiroplasma、Tediphilus、Acinetobacter 和 Pseudomonas 组成。尽管在微生物组组成中观察到细菌属的多样性和丰度很大，但对 160 只采采蝇的统计分析显示，其与苍蝇的感染状态和采样地点有关。此外，携带刚果锥虫 Savanah 型的采采蝇显示出与未感染苍蝇不同的细菌菌群组成。此外，我们的研究表明，36 个细菌属仅存在于未感染的苍蝇中，这可能表明它们可能参与了苍蝇的抗性；除了 Cupriavidus 外，它们的相对丰度都很低。一些属，包括 Acinetobacter、Cutibacterium、Pseudomonas 和 Tepidiphilus，虽然存在于感染和未感染的苍蝇中，但与未感染的苍蝇状态有关。因此，需要进一步评估它们的实际作用，以确定它们中的一些是否可以成为控制采采蝇媒介效能的目标，从而控制疾病。最后，在比较在 4 次流行病学调查中收集的采采蝇中鉴定的细菌属时，发现 39 个属至少存在于 2 次采样活动的苍蝇中。
