The Tripartite Interaction of Host Immunity–Bacillus thuringiensis Infection–Gut Microbiota

Li, Shuzhong; Mandal, Surajit De; Xu, Xi; Jin, Fengliang

doi:10.3390/toxins12080514

Cited by 35 publications

(25 citation statements)

References 142 publications

(189 reference statements)

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“…aegypti since treated larvae were characterized by a lower bacterial diversity, compared to untreated individuals [ 399 ]. The interaction of Bt toxins with the midgut microbiota and the immune system of the insects was recorded, as reviewed by Li et al [ 400 ]. The microbiota can play a major role in the antiviral response of mosquitoes, either by secreting antiviral or proviral molecules or by modulating the immunity response [ 401 , 402 , 403 , 404 ].…”

Section: Impact On Life Traitsmentioning

confidence: 99%

Bacterial Toxins Active against Mosquitoes: Mode of Action and Resistance

Silva-Filha

Romão

Rezende

et al. 2021

Toxins

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Larvicides based on the bacteria Bacillus thuringiensis svar. israelensis (Bti) and Lysinibacillus sphaericus are effective and environmentally safe compounds for the control of dipteran insects of medical importance. They produce crystals that display specific and potent insecticidal activity against larvae. Bti crystals are composed of multiple protoxins: three from the three-domain Cry type family, which bind to different cell receptors in the midgut, and one cytolytic (Cyt1Aa) protoxin that can insert itself into the cell membrane and act as surrogate receptor of the Cry toxins. Together, those toxins display a complex mode of action that shows a low risk of resistance selection. L. sphaericus crystals contain one major binary toxin that display an outstanding persistence in field conditions, which is superior to Bti. However, the action of the Bin toxin based on its interaction with a single receptor is vulnerable for resistance selection in insects. In this review we present the most recent data on the mode of action and synergism of these toxins, resistance issues, and examples of their use worldwide. Data reported in recent years improved our understanding of the mechanism of action of these toxins, showed that their combined use can enhance their activity and counteract resistance, and reinforced their relevance for mosquito control programs in the future years.

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Section: Impact On Life Traitsmentioning

confidence: 99%

Bacterial Toxins Active against Mosquitoes: Mode of Action and Resistance

Silva-Filha

Romão

Rezende

et al. 2021

Toxins

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show abstract

“…Following the infection process of Bti , both the insect immune system and microbiota were changed. The activated immune response and dysbiosis of the microbiota have an important effect on the pathogenicity of Bti 52 . A better understanding of the abundance and compositional changes of bacteria could potentially be helpful to illuminating the interaction between Bti toxicity and microbiota, exploring available bacterial taxa strengthening Bti toxicity to mosquitoes, which finally contributes to the development of new sustainable mosquito control strategies.…”

Section: Discussionmentioning

confidence: 99%

“…Consistent with these results, we also found enriched genes associated with the Toll and imd signaling pathway, which are two major immune pathways critical for the immune response that functions through the production of antimicrobial peptides (AMPs). AMPs are among the important members involved in humoral immune responses of insects 52 . The pronounced upregulation of gene expression associated with the Toll and imd signaling pathway indicated that larvae exposed to Bti mount a strong defense.…”

Section: Discussionmentioning

confidence: 99%

Microbiota and transcriptome changes of Culex pipiens pallens larvae exposed to Bacillus thuringiensis israelensis

Zhang

Liu

Zhang

et al. 2021

Sci Rep

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Culex pipiens pallens is an important vector of lymphatic filariasis and epidemic encephalitis. Mosquito control is the main strategy used for the prevention of mosquito-borne diseases. Bacillus thuringiensis israelensis (Bti) is an entomopathogenic bacterium widely used in mosquito control. In this study, we profiled the microbiota and transcriptional response of the larvae of Cx. pipiens pallens exposed to different concentrations of Bti. The results demonstrated that Bti induced a significant effect on both the microbiota and gene expression of Cx. pipiens pallens. Compared to the control group, the predominant bacteria changed from Actinobacteria to Firmicutes, and with increase in the concentration of Bti, the abundance of Actinobacteria was gradually reduced. Similar changes were also detected at the genus level, where Bacillus replaced Microbacterium, becoming the predominant genus in Bti-exposed groups. Furthermore, alpha diversity analysis indicated that Bti exposure changed the diversity of the microbota, possibly because the dysbiosis caused by the Bti infection inhibits some bacteria and provides opportunities to other opportunistic taxa. Pathway analysis revealed significant enhancement for processes associated with sphingolipid metabolism, glutathione metabolism and glycerophospholipid metabolism between all Bti-exposed groups and control group. Additionally, genes associated with the Toll and Imd signaling pathway were found to be notably upregulated. Bti infection significantly changed the bacterial community of larvae of Cx. pipiens pallens.

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“…The intestinal microbiota contained in insects varies greatly with insect species, feeding habits, and living environment ( Xiao et al, 2017 ; Li S. et al, 2020 ). The intestinal microbiota of insects is found to be directly related to the physiological activities of the host, such as nutrient utilization, immune defense and regulation, metabolism, and development.…”

Section: The Resistance Mechanisms Of Insects Against Cry Toxinsmentioning

confidence: 99%

Which Is Stronger? A Continuing Battle Between Cry Toxins and Insects

Luo

et al. 2021

Front. Microbiol.

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In this article, we review the latest works on the insecticidal mechanisms of Bacillus thuringiensis Cry toxins and the resistance mechanisms of insects against Cry toxins. Currently, there are two models of insecticidal mechanisms for Cry toxins, namely, the sequential binding model and the signaling pathway model. In the sequential binding model, Cry toxins are activated to bind to their cognate receptors in the mid-intestinal epithelial cell membrane, such as the glycophosphatidylinositol (GPI)-anchored aminopeptidases-N (APNs), alkaline phosphatases (ALPs), cadherins, and ABC transporters, to form pores that elicit cell lysis, while in the signaling pathway model, the activated Cry toxins first bind to the cadherin receptor, triggering an extensive cell signaling cascade to induce cell apoptosis. However, these two models cannot seem to fully describe the complexity of the insecticidal process of Cry toxins, and new models are required. Regarding the resistance mechanism against Cry toxins, the main method insects employed is to reduce the effective binding of Cry toxins to their cognate cell membrane receptors by gene mutations, or to reduce the expression levels of the corresponding receptors by trans-regulation. Moreover, the epigenetic mechanisms, host intestinal microbiota, and detoxification enzymes also play significant roles in the insects’ resistance against Cry toxins. Today, high-throughput sequencing technologies like transcriptomics, proteomics, and metagenomics are powerful weapons for studying the insecticidal mechanisms of Cry toxins and the resistance mechanisms of insects. We believe that this review shall shed some light on the interactions between Cry toxins and insects, which can further facilitate the development and utilization of Cry toxins.

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The Tripartite Interaction of Host Immunity–Bacillus thuringiensis Infection–Gut Microbiota

Cited by 35 publications

References 142 publications

Bacterial Toxins Active against Mosquitoes: Mode of Action and Resistance

Bacterial Toxins Active against Mosquitoes: Mode of Action and Resistance

Microbiota and transcriptome changes of Culex pipiens pallens larvae exposed to Bacillus thuringiensis israelensis

Which Is Stronger? A Continuing Battle Between Cry Toxins and Insects

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