Understanding of bacterial virulence using the silkworm infection model

Kaito, Chikara

doi:10.5582/ddt.2016.01020

Cited by 15 publications

(8 citation statements)

References 45 publications

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“…Staphylococcus spp. are generally pathogenic bacteria causing various diseases in human by producing various factors that are defensive against the host immune system, adhesive to host tissues, and toxins that destroy host tissues [ 18 ]. In insects, bacteria belonging to this genus are prevalent in Lepidoptera of the families Sphingidae and Noctuidae , where they could contribute to digestion and development of the velvet bean caterpillar [ 19 ].…”

Section: Discussionmentioning

confidence: 99%

Bacterial diversity obtained by culturable approaches in the gut of Glossina pallidipes population from a non sleeping sickness focus in Tanzania: preliminary results

et al. 2018

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BackgroundGlossina pallidipes is a haematophagous insect that serves as a cyclic transmitter of trypanosomes causing African Trypanosomiasis (AT). To fully assess the role of G. pallidipes in the epidemiology of AT, especially the human form of the disease (HAT), it is essential to know the microbial diversity inhabiting the gut of natural fly populations. This study aimed to examine the diversity of G. pallidipes fly gut bacteria by culture-dependent approaches.Results113 bacterial isolates were obtained from aerobic and anaerobic microorganisms originating from the gut of G. pallidipes. 16S rDNA of each isolate was PCR amplified and sequenced. The overall majority of identified bacteria belonged in descending order to the Firmicutes (86.6%), Actinobacteria (7.6%), Proteobacteria (5.5%)and Bacteroidetes (0.3%). Diversity of Firmicutes was found higher when enrichments and isolation were performed under anaerobic conditions than aerobic ones. Experiments conducted in the absence of oxygen (anaerobiosis) led to the isolation of bacteria pertaining to four phyla (83% Firmicutes, 15% Actinobacteria, 1% Proteobacteria and 0.5% Bacteroidetes, whereas those conducted in the presence of oxygen (aerobiosis) led to the isolation of bacteria affiliated to two phyla only (90% Firmicutes and 10% Proteobacteria). Phylogenetic analyses placed these isolates into 11 genera namely Bacillus, Acinetobacter, Mesorhizobium, Paracoccus, Microbacterium, Micrococcus, Arthrobacter, Corynobacterium, Curtobacterium, Vagococcus and Dietzia spp.which are known to be either facultative anaerobes, aerobes, or even microaerobes.ConclusionThis study shows that G. pallidipes fly gut is an environmental reservoir for a vast number of bacterial species, which are likely to be important for ecological microbial well being of the fly and possibly on differing vectorial competence and refractoriness against AT epidemiology.Electronic supplementary materialThe online version of this article (10.1186/s12866-018-1288-3) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

Bacterial diversity obtained by culturable approaches in the gut of Glossina pallidipes population from a non sleeping sickness focus in Tanzania: preliminary results

et al. 2018

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“…The body size of silkworm larva (3-85 mm) and the period of the larvae (25 days) facilitate injection of pathogens and experimental repetitions. Therefore, B. mori larvae have been used as infection models for experiments focused on a large variety of agents, such as bacteria, viruses, and fungi (Kaito et al, 2002;Jiang et al, 2016;Kaito, 2016;Uchida et al, 2016). Recently, non-mammalian infection models, including the wax moth (Galleria mellonella), fruit fly (Drosophila melanogaster), cockroach (Blaptica dubia), and zebrafish (Danio rerio), have all been employed as models to promote understanding of hostpathogen interactions associated with Francisella (Aperis et al, 2007;Vonkavaara et al, 2008;Vojtech et al, 2009;Ahlund et al, 2010;Moule et al, 2010;Eklund et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Identification of Membrane-Bound Lytic Murein Transglycosylase A (MltA) as a Growth Factor for Francisella novicida in a Silkworm Infection Model

Nakamura

Shimizu

Inagaki

et al. 2021

Front. Cell. Infect. Microbiol.

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Francisella tularensis, the causative agent of tularemia, is transmitted by arthropod vectors within mammalian hosts. The detailed mechanisms contributing to growth and survival of Francisella within arthropod remain poorly understood. To identify novel factors supporting growth and survival of Francisella within arthropods, a transposon mutant library of F. tularensis subsp. novicida (F. novicida) was screened using an F. novicida–silkworm infection model. Among 750 transposon mutants screened, the mltA-encoding membrane-bound lytic murein transglycosylase A (MltA) was identified as a novel growth factor of F. novicida in silkworms. Silkworms infection with an mltA deletion mutant (ΔmltA) resulted in a reduction in the number of bacteria and prolonged survival. The ΔmltA strain exhibited limited intracellular growth and cytotoxicity in BmN4 silkworm ovary cells. Moreover, the ΔmltA strain induced higher expression of the antimicrobial peptide in silkworms compared to the wild-type strain. These results suggest that F. novicida MltA contributes to the survival of F. novicida in silkworms via immune suppression-related mechanisms. Intracellular growth of the ΔmltA strain was also reduced in human monocyte THP-1 cells. These results also suggest the contribution of MltA to pathogenicity in humans and utility of the F. novicida–silkworm infection model to explore Francisella infection.

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“…As insect pests develop resistance to chemical insecticides, PC toxin is a promising biological insecticide with a range of benefits. Further, studying the immune responses of silkworm to bacterial toxins can contribute to further insights into the interaction between hosts and pathogens [6, 7]. One of the constituents of PC toxin, α -toxin, shows oral lethality to silkworm larvae and promotes infection and disease.…”

Section: Introductionmentioning

confidence: 99%

Gene Expression Pattern and Regulatory Network of α-Toxin Treatment in Bombyx mori

Feng

Lin

Gong

et al. 2019

International Journal of Genomics

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Bacillus bombyseptieus is a pathogen of Bombyx mori; it can cause bacterial septicemia in silkworm. One of the components of the parasporal crystal toxin of B. bombyseptieus, α-toxin, plays an important role in the process of infection in silkworm. In this study, we investigated the immune response of silkworm induced by α-toxin by using RNA-seq. We compared the changes in gene expression in the midgut, fatbody, and hemocytes of silkworm and in the B. mori embryonic cell line (BmE) after treatment with α-toxin and identified 952 differentially expressed genes and 353 differentially expressed long noncoding RNAs (lncRNAs). These regulated genes in different tissues were found to be enriched in different pathways. The upregulated genes in the midgut were mainly involved in peptidoglycan catabolic process and tyrosine kinase signaling pathway, whereas the downregulated genes were mainly involved in chitin metabolic pathways. The upregulated genes in fatbody were also involved in peptidoglycan catabolic process, but they were for a different peptidoglycan subtype. Further, genes encoding cecropins were enriched in the fatbody. The downregulated genes were mainly involved in the metabolic pathways of fundamental substances such as cellular protein metabolic process and nucleobase-containing compound metabolic process. These results suggest that α-toxin can induce various immune responses in silkworm, and further studies are warranted to understand the mechanism of α-toxin action in silkworm. Further, lncRNAs and differentially expressed genes were correlated using coexpression network analysis. Our findings revealed potential candidate genes and lncRNAs that might play important physiological functions in the immune response to α-toxins in silkworm.

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Understanding of bacterial virulence using the silkworm infection model

Cited by 15 publications

References 45 publications

Bacterial diversity obtained by culturable approaches in the gut of Glossina pallidipes population from a non sleeping sickness focus in Tanzania: preliminary results

Bacterial diversity obtained by culturable approaches in the gut of Glossina pallidipes population from a non sleeping sickness focus in Tanzania: preliminary results

Identification of Membrane-Bound Lytic Murein Transglycosylase A (MltA) as a Growth Factor for Francisella novicida in a Silkworm Infection Model

Gene Expression Pattern and Regulatory Network of α-Toxin Treatment in Bombyx mori

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