Bacillus thuringiensis serotype H34 isolated from human and insecticidal strains serotypes 3a3b and H14 can lead to death of immunocompetent mice after pulmonary infection

Hernandez, Éric

doi:10.1016/s0928-8244(99)00005-x

Cited by 31 publications

(60 citation statements)

References 4 publications

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“…The cause of death is unknown, and, in mice, it is unlikely to be due to the growth of the bacteria. However, as previously described (Hernandez et al, 1999), the syndromes observed in infected mice suggest that haemolysin production may be involved in death. These opportunistic properties have been lost (or highly reduced) in the ∆plcR mutants of the B. thuringiensis and B. cereus strains used in this study, and they are also absent from a B. anthracis vaccine strain known to be defective in PlcR activity (Agaisse et al, 1999).…”

Section: Discussionsupporting

confidence: 62%

“…Nasal instillation of 10) or 5i10( spores of the 407 Cry − strain and of the B. cereus strain per mouse rapidly resulted in high mortality rates (Table 1). Mice died within 24 h, with syndromes similar to those described for the B. thuringiensis strain konkukian (Hernandez et al, 1999). However, instillation of 10( spores per mouse in the same volume (50 µl) resulted in no deaths with 407 Cry − spores and a high mortality rate with the B. cereus strain, which suggests that the two strains differ in pathogenicity.…”

Section: Cytotoxic and Haemolytic Activities Are Controlled By Plcrmentioning

confidence: 63%

“…The opportunistic properties of B. thuringiensis and B. cereus in mice Hernandez et al (1998Hernandez et al ( , 1999 recently showed that some B. thuringiensis strains are pathogenic to mice by nasal instillation. We first determined whether the B. thuringiensis 407 Cry − strain (subspecies thuringiensis) and B. cereus ATCC 14579 belonged to this group.…”

Section: Cytotoxic and Haemolytic Activities Are Controlled By Plcrmentioning

confidence: 99%

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The plcR regulon is involved in the opportunistic properties of Bacillus thuringiensis and Bacillus cereus in mice and insects

Ramisse²,

et al. 2000

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Bacillus thuringiensis has been widely used for 40 years as a safe biopesticide for controlling agricultural pests and mosquitoes because it produces insecticidal crystal proteins. However, spores have also been shown to contribute to overall entomopathogenicity. Here, the opportunistic properties of acrystalliferous B. thuringiensis Cry N and Bacillus cereus strains were investigated in an insect species, Galleria mellonella, and in a mammal, BALB/c mice. In both animal models, the pathogenicity of the two bacterial species was similar. Mutant strains were constructed in which the plcR gene, encoding a pleiotropic regulator of extracellular factors, was disrupted. In larvae, coingestion of 10 6 spores of the parental strain with a sublethal concentration of Cry1C toxin caused 70 % mortality whereas only 7 % mortality was recorded if spores of the ∆plcR mutant strain were used. In mice, nasal instillation of 10 8 spores of the parental strain caused 100 % mortality whereas instillation with the same number of ∆plcR strain spores caused much lower or no mortality. Similar effects were obtained if vegetative cells were used instead of spores.The cause of death is unknown and is unlikely to be due to actual growth of the bacteria in mice. The lesions caused by B. thuringiensis supernatant in infected mice suggested that haemolytic toxins were involved. The cytolytic properties of strains of B. thuringiensis and B. cereus, using sheep, horse and human erythrocytes and G. mellonella haemocytes, were therefore investigated. The level of cytolytic activity is highly reduced in ∆plcR strains.Together, the results indicate that the pathogenicity of B. thuringiensis strain 407 and B. cereus strain ATCC 14579 is controlled by PlcR.

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Section: Discussionsupporting

confidence: 62%

Section: Cytotoxic and Haemolytic Activities Are Controlled By Plcrmentioning

confidence: 63%

Section: Cytotoxic and Haemolytic Activities Are Controlled By Plcrmentioning

confidence: 99%

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The plcR regulon is involved in the opportunistic properties of Bacillus thuringiensis and Bacillus cereus in mice and insects

Ramisse²,

et al. 2000

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“…thuringiensis and B. cereus establish persistent infections with infiltration of phagocytes, implying that the bacteria circumvent the host immune system (2,14,31). However, interactions between the host immune cells and these bacteria are still poorly characterized, and how they resist the immune defense system remains unknown.…”

mentioning

confidence: 99%

The InhA Metalloproteases ofBacillus cereusContribute Concomitantly to Virulence

et al. 2010

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The virulence of Bacillus cereus requires that bacteria have the capacity to colonize their host, degrade specific tissues, and circumvent the host immune system. To study this aspect of pathogenesis, we focused on three metalloproteases, InhA1, InhA2, and InhA3, which share more than 66% identity. The expression of these metalloprotease genes was assessed by transcriptional fusions with a lacZ reporter gene. The expression profiles suggest a complementary time course of InhA production. Indeed, the genes are simultaneously expressed but are oppositely controlled during stationary phase. We constructed single and multiple inhA mutants and assessed the bacterial locations of the proteins as well as their individual or additive roles in macrophage escape and toxicity, antibacterial-peptide cleavage, and virulence. InhA1, a major component of the spore exosporium, is the only InhA metalloprotease involved in bacterial escape from macrophages. A mutant lacking inhA1, inhA2, and inhA3 shows a strong decrease in the level of virulence for insects. Taken together, these results show that the InhA metalloproteases of B. cereus are important virulence factors that may allow the bacteria to counteract the host immune system.

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“…Moreover, a B. cereus strain has caused lethal infections resembling anthrax (36), and several cases of bacteremia in preterm neonates have been described, highlighting this public health problem (35,49). Infections are characterized by bacterial accumulation despite the induction of inflammation (33,34). Therefore, B. cereus is able to persist and to counteract the host immune system.…”

mentioning

confidence: 99%

InhA1, NprA, and HlyII as Candidates for Markers To Differentiate Pathogenic from NonpathogenicBacillus cereusStrains

Cadot

Tran

Vignaud³

et al. 2010

J Clin Microbiol

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Bacillus cereus is found in food, soil, and plants, and the ability to cause food-borne diseases and opportunistic infection presumably varies among strains. Therefore, measuring harmful toxin production, in addition to the detection of the bacterium itself, may be key for food and hospital safety purposes. All previous studies have focused on the main known virulence factors, cereulide, Hbl, Nhe, and CytK. We examined whether other virulence factors may be specific to pathogenic strains. InhA1, NprA, and HlyII have been described as possibly contributing to B. cereus pathogenicity. We report the prevalence and expression profiles of these three new virulence factor genes among 57 B. cereus strains isolated from various sources, including isolates associated with gastrointestinal and nongastrointestinal diseases. Using PCR, quantitative reverse transcriptase PCR, and virulence in vivo assays, we unraveled these factors as potential markers to differentiate pathogenic from nonpathogenic strains. We show that the hlyII gene is carried only by strains with a pathogenic potential and that the expression levels of inhA1 and nprA are higher in the pathogenic than in the nonpathogenic group of strains studied. These data deliver useful information about the pathogenicity of various B. cereus strains.

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Bacillus thuringiensis serotype H34 isolated from human and insecticidal strains serotypes 3a3b and H14 can lead to death of immunocompetent mice after pulmonary infection

Cited by 31 publications

References 4 publications

The plcR regulon is involved in the opportunistic properties of Bacillus thuringiensis and Bacillus cereus in mice and insects

The plcR regulon is involved in the opportunistic properties of Bacillus thuringiensis and Bacillus cereus in mice and insects

The InhA Metalloproteases ofBacillus cereusContribute Concomitantly to Virulence

InhA1, NprA, and HlyII as Candidates for Markers To Differentiate Pathogenic from NonpathogenicBacillus cereusStrains

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