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Emerging B. cereus strains that cause anthrax-like disease have been isolated in Cameroon (CA strain) and Côte d'Ivoire (CI strain). These strains are unusual, because their genomic characterisation shows that they belong to the B. cereus species, although they harbour two plasmids, pBCXO1 and pBCXO2, that are highly similar to the pXO1 and pXO2 plasmids of B. anthracis that encode the toxins and the polyglutamate capsule respectively. The virulence factors implicated in the pathogenicity of these B. cereus bv anthracis strains remain to be characterised. We tested their virulence by cutaneous and intranasal delivery in mice and guinea pigs; they were as virulent as wild-type B. anthracis. Unlike as described for pXO2-cured B. anthracis, the CA strain cured of the pBCXO2 plasmid was still highly virulent, showing the existence of other virulence factors. Indeed, these strains concomitantly expressed a hyaluronic acid (HA) capsule and the B. anthracis polyglutamate (PDGA) capsule. The HA capsule was encoded by the hasACB operon on pBCXO1, and its expression was regulated by the global transcription regulator AtxA, which controls anthrax toxins and PDGA capsule in B. anthracis. Thus, the HA and PDGA capsules and toxins were co-regulated by AtxA. We explored the respective effect of the virulence factors on colonisation and dissemination of CA within its host by constructing bioluminescent mutants. Expression of the HA capsule by itself led to local multiplication and, during intranasal infection, to local dissemination to the adjacent brain tissue. Co-expression of either toxins or PDGA capsule with HA capsule enabled systemic dissemination, thus providing a clear evolutionary advantage. Protection against infection by B. cereus bv anthracis required the same vaccination formulation as that used against B. anthracis. Thus, these strains, at the frontier between B. anthracis and B. cereus, provide insight into how the monomorphic B. anthracis may have emerged.

Bacillus cereus biovar anthracis (Bcbva) causes anthrax-like disease in animals, particularly in the non-human primates and great apes of West and Central Africa. Genomic analyses revealed Bcbva as a member of the B . cereus species that carries two plasmids, pBCXO1 and pBCXO2, which have high sequence homology to the B . anthracis toxin and polyglutamate capsule encoding plasmids pXO1 and pXO2, respectively. To date, only a few studies have investigated the effect of variations in Bcbva sporulation, toxin, and capsule synthesis on animal and macrophage pathogenicity compared to B . anthracis , therefore more research is needed to gain a better understanding of the pathogenesis of this emerging infection. Here, we report that Bcbva can multiply and vegetatively survive on nutrient-rich media for a minimum of six days while generating spores. Sporulation of Bcbva occurred faster and more extensively than B . anthracis Ames. Bcbva tended to secrete less protective antigen (PA) than B . anthracis Ames when cultured in growth medium. We found Bcbva produced a substantially higher amount of attached poly-ƴ-D-glutamic acid (PDGA) capsule than B . anthracis Ames when grown in medium supplemented with human serum and CO 2 . In a phagocytosis assay, Bcbva spores showed reduced internalization by mouse macrophages compared to B . anthracis Ames. Our research demonstrated that Bcbva is more virulent than B . anthracis Ames using two in vivo models, Galleria mellonella larvae and guinea pigs. Following that, the efficacy of the veterinary vaccine Sterne strain 34F2 against anthrax-like disease was assessed in guinea pigs. Sterne vaccinated guinea pigs had significantly increased anti-PA titers compared to the unvaccinated control group. Toxin neutralizing antibody titers in vaccinated guinea pigs correlated with anti-PA titers. This indicates the Sterne vaccine provides adequate protection against Bcbva infection in laboratory animals.

The Centers for Disease Control and Prevention (CDC) classifies Bacillus anthracis as one of the most dangerous pathogens that may affect public health and national security. Due to its importance as a potential biological weapon, this bacteria has been classified in the highest category A, together with such pathogens as variola virus or botulinum neurotoxin. Characteristic features of this pathogen that increase its military importance are the ease of its cultivation, transport, and storage and its ability to create survival forms that are extremely resistant to environmental conditions. However, beyond bioterrorism, B. anthracis is also a naturally occurring pathogen. Anthrax outbreaks occur in livestock and wildlife, particularly in spore-contaminated regions of Africa, Asia, and North America. Spores persist for decades, leading to recurrent infections and zoonotic transmission through direct contact, inhalation, or consumption of contaminated meat. This work presents a new electrochemical method for detecting and quantifying B. anthracis in spore form using a selective immune reaction. The developed method is based on the thiol-modified electrodes that constitute the sensing element of the electrochemical system. Tests with the B. anthracis spore suspension showed that the detection limit for this pathogen is as low as 103 CFU/mL. Furthermore, it was possible to quantify the analyte with a sensitivity of 11 mV/log (CFU/mL). Due to several features, such as low unit cost, portability, and minimal apparatus demands, this method can be easily implemented in field analyzers for this pathogen and provides an alternative to currently used techniques and devices.

Through full genome analyses of four atypical Bacillus cereus isolates, designated B. cereus biovar anthracis, we describe a distinct clade within the B. cereus group that presents with anthrax-like disease, carrying virulence plasmids similar to those of classic Bacillus anthracis. We have isolated members of this clade from different mammals (wild chimpanzees, gorillas, an elephant and goats) in West and Central Africa (Côte d'Ivoire, Cameroon, Central African Republic and Democratic Republic of Congo). The isolates shared several phenotypic features of both B. anthracis and B. cereus, but differed amongst each other in motility and their resistance or sensitivity to penicillin. They all possessed the same mutation in the regulator gene plcR, different from the one found in B. anthracis, and in addition, carry genes which enable them to produce a second capsule composed of hyaluronic acid. Our findings show the existence of a discrete clade of the B. cereus group capable of causing anthrax-like disease, found in areas of high biodiversity, which are possibly also the origin of the worldwide distributed B. anthracis. Establishing the impact of these pathogenic bacteria on threatened wildlife species will require systematic investigation. Furthermore, the consumption of wildlife found dead by the local population and presence in a domestic animal reveal potential sources of exposure to humans.

A study was conducted to assess the efficacy of ozone gas in inactivating spores of both Bacillus anthracis and Bacillus subtilis inoculated onto six building materials (glass, wood, carpet, laminate, galvanized metal, and wallboard paper). Testing conditions consisted of ozone gas concentrations ranging from 7,000-12,000 parts per million (ppm), contact times from 4 to 12 h, and two relative humidity (RH) levels of 75 and 85%. Results showed that increasing the ozone concentration, contact time, and RH generally increased decontamination efficacy. The materials in which the highest decontamination efficacy was achieved for B. anthracis spores were wallboard paper, carpet, and wood with ≥ 6 log10 reduction (LR) occurring with 9,800 ppm ozone, 85% RH, for 6 h. The laminate and galvanized metal materials were generally more difficult to decontaminate, requiring 12,000 ppm ozone, 85% RH, and 9-12 h contact time to achieve ≥6 LR of B. anthracis. Lastly, overall, there were no significant differences in decontamination efficacy between the two species.

An anthrax-causing agent, Bacillus cereus biovar anthracis , is a persistent and widespread cause of death for a broad range of mammalian hosts in a tropical rainforest, with important implications for the conservation of mammals such as chimpanzees. Anthrax threatens rainforest wildlife Anthrax is a disease that affects wildlife, livestock and humans, largely in low- and middle-income countries. To date, the disease has largely been studied in arid ecosystems, where outbreaks are commonly reported. Fabian Leendertz and colleagues study the dynamics of an anthrax-causing bacterium in a rainforest in Taï National Park, Ivory Coast, using mammal and fly samples collected over three decades. They find that anthrax is an important cause of mortality in diverse mammalian species, including chimpanzees, monkeys, duikers, mongooses and porcupines. Demographic modelling suggests that anthrax will speed up the decline of local chimpanzee populations, potentially leading to their extinction from the region. Anthrax is a globally important animal disease and zoonosis. Despite this, our current knowledge of anthrax ecology is largely limited to arid ecosystems, where outbreaks are most commonly reported 1 , 2 , 3 . Here we show that the dynamics of an anthrax-causing agent, Bacillus cereus biovar anthracis , in a tropical rainforest have severe consequences for local wildlife communities. Using data and samples collected over three decades, we show that rainforest anthrax is a persistent and widespread cause of death for a broad range of mammalian hosts. We predict that this pathogen will accelerate the decline and possibly result in the extirpation of local chimpanzee ( Pan troglodytes verus ) populations. We present the epidemiology of a cryptic pathogen and show that its presence has important implications for conservation.

Bacillus anthracis is a zoonotic organism that causes the disease anthrax due to the activity of virulence factors harbored on plasmids pXO1 and pXO2. Inhalation of B. anthracis spores results in pneumonic disease that progresses quickly, and often results in lethality in the absence of medical countermeasure (MCM) intervention. Recently, reports have identified Bacillus cereus isolates that possess pXO1 and pXO2-like plasmids and cause an anthrax-like disease. These isolates have been named B. cereus biovar anthracis , or Bcbva. To evaluate disease course of Bcbva, the inhalational median lethal dose (INHLD 50 ) was determined for two isolates, Bcbva Cameroon (CA) and Bcbva Cote d’Ivoire (CI), using the New Zealand white (NZW) rabbit inhalation anthrax model and compared to established B. anthracis inhalation data. Furthermore, disease progression and anthrax MCM efficacies were evaluated by quantifying temperature responses, bacteremia, and virulence factor production in both survivor and non-survivor animals. This study determined that the rabbit INHLD 50 values for Bcbva CA and CI were similar to that published for B. anthracis Ames. The mean time to significant increase in body temperature (SIBT) and death were dose dependent for both Bcbva isolates, and all animals that succumbed to aerosol exposure displayed SIBT prior to death. Serum hyaluronic acid concentration increased prior to mortality in animals challenged with Bcbva and differences were observed in serum protective antigen concentration in animals challenged with Bcbva compared to B. anthracis . Pre-exposure vaccination with Anthrax Vaccine Adsorbed (AVA) and post-exposure prophylaxis of levofloxacin with or without AVA vaccination were effective against a challenge of ~200 INHLD 50 of Bcbva CA or CI. Collectively, these data suggest that anthrax-like disease caused by Bcbva is similar to that caused by B. anthracis Ames 2084, and that currently available countermeasures are effective against inhalation exposure to Bcbva.

Anthrax is a zoonotic disease that remains endemic in Uganda, particularly in cattle-keeping areas. On December 28, 2023, the first suspected human case of anthrax was detected in Amudat District. We investigated to determine the outbreak's magnitude, identify risk factors, and recommend prevention and control measures. We defined a suspected cutaneous anthrax case as acute onset of ≥2 of the following: skin lesions (papule, vesicle, or eschar) on exposed areas such as the hands, forearms, shoulders, back, thighs or face, localized itching, redness, swelling, or regional lymphadenopathy, in Amudat residents from December 2023-June 2024. A confirmed case was a suspected case with PCR-positive test for Bacillus anthracis. In unmatched case-control study (1:3 ratio), we compared exposures among 40 cases and 120 controls. We identified cases through house-to-house search, medical record reviews, and snowballing among case-persons. Human and animal samples were collected and tested, alongside an environmental assessment. We used multivariable logistic regression to identify associated risk factors. We identified 102 cutaneous anthrax cases, including 7 confirmed cases; none died. The outbreak lasted 7 months, peaking in March 2024, with an overall attack rate of 169/100,000 (males: 196/100,000; females: 138/100,000). Use of cattle hides as bedding (OR=12; 95% CI:2.7-52) and butchering cattle carcasses (OR=6; 95% CI:1.8-19) were significantly associated with anthrax. The highest infection risk was observed among individuals with multiple exposures: butchered only (OR = 6.9, 95% CI:2.6-18), butchered and carried cattle parts (OR = 11, 95% CI:1.2-96), butchered and skinned (OR = 14, 95% CI:3.5-56), and butchered, carried, and skinned (OR = 17, 95% CI:1.6-219). No livestock had been vaccinated prior to the outbreak. The outbreak was associated to use of cattle hides as bedding and the butchering of cattle carcasses. We recommended community education, livestock vaccination, and safe carcass handling to prevent future outbreaks.

Anthrax is a fatal disease caused by strains of Bacillus anthracis. Members of this monophyletic species are non motile and are all characterized by the presence of four prophages and a nonsense mutation in the plcR regulator gene. Here we report the complete genome sequence of a Bacillus strain isolated from a chimpanzee that had died with clinical symptoms of anthrax. Unlike classic B. anthracis, this strain was motile and lacked the four prohages and the nonsense mutation. Four replicons were identified, a chromosome and three plasmids. Comparative genome analysis revealed that the chromosome resembles those of non-B. anthracis members of the Bacillus cereus group, whereas two plasmids were identical to the anthrax virulence plasmids pXO1 and pXO2. The function of the newly discovered third plasmid with a length of 14 kbp is unknown. A detailed comparison of genomic loci encoding key features confirmed a higher similarity to B. thuringiensis serovar konkukian strain 97-27 and B. cereus E33L than to B. anthracis strains. For the first time we describe the sequence of an anthrax causing bacterium possessing both anthrax plasmids that apparently does not belong to the monophyletic group of all so far known B. anthracis strains and that differs in important diagnostic features. The data suggest that this bacterium has evolved from a B. cereus strain independently from the classic B. anthracis strains and established a B. anthracis lifestyle. Therefore we suggest to designate this isolate as \"B. cereus variety (var.) anthracis\".