Molecular subtyping of Bacillus anthracis and the 2001 bioterrorism-associated anthrax outbreak, United States.
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ABSTRACT:
SUBMITTER: Hoffmaster AR
PROVIDER: S-EPMC2730295 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BACKGROUND:Bacillus cereus biovar anthracis (Bcbva) is an emergent bacterium closely related to Bacillus anthracis, the etiological agent of anthrax. The latter has a worldwide distribution and usually causes infectious disease in mammals associated with savanna ecosystems. Bcbva was identified in humid tropical forests of Côte d'Ivoire in 2001. Here, we characterize the potential geographic distributions of Bcbva in West Africa and B. anthracis in sub-Saharan Africa using an ecological niche modeling approach. METHODOLOGY/PRINCIPAL FINDINGS:Georeferenced occurrence data for B. anthracis and Bcbva were obtained from public data repositories and the scientific literature. Combinations of temperature, humidity, vegetation greenness, and soils values served as environmental variables in model calibrations. To predict the potential distribution of suitable environments for each pathogen across the study region, parameter values derived from the median of 10 replicates of the best-performing model for each pathogen were used. We found suitable environments predicted for B. anthracis across areas of confirmed and suspected anthrax activity in sub-Saharan Africa, including an east-west corridor from Ethiopia to Sierra Leone in the Sahel region and multiple areas in eastern, central, and southern Africa. The study area for Bcbva was restricted to West and Central Africa to reflect areas that have likely been accessible to Bcbva by dispersal. Model predicted values indicated potential suitable environments within humid forested environments. Background similarity tests in geographic space indicated statistical support to reject the null hypothesis of similarity when comparing environments associated with B. anthracis to those of Bcbva and when comparing humidity values and soils values individually. We failed to reject the null hypothesis of similarity when comparing environments associated with Bcbva to those of B. anthracis, suggesting that additional investigation is needed to provide a more robust characterization of the Bcbva niche. CONCLUSIONS/SIGNIFICANCE:This study represents the first time that the environmental and geographic distribution of Bcbva has been mapped. We document likely differences in ecological niche-and consequently in geographic distribution-between Bcbva and typical B. anthracis, and areas of possible co-occurrence between the two. We provide information crucial to guiding and improving monitoring efforts focused on these pathogens.
| S-EPMC7082064 | biostudies-literature
Project description:In July 2012, an anthrax outbreak occurred among cattle in northern Germany resulting in ten losses. Here, we report the draft genome sequence ofBacillus anthracisstrain Stendal, isolated from one of the diseased cows.
| S-EPMC4824258 | biostudies-literature
Project description:Bacillus anthracis, a spore-forming gram-positive bacterium, causes anthrax. The external surface of the exosporium is coated with glycosylated proteins. The sugar additions are capped with the unique monosaccharide anthrose. The West African Group (WAG) B. anthracis have mutations rendering them anthrose deficient. Through genome sequencing, we identified 2 different large chromosomal deletions within the anthrose biosynthetic operon of B. anthracis strains from Chile and Poland. In silico analysis identified an anthrose-deficient strain in the anthrax outbreak among European heroin users. Anthrose-deficient strains are no longer restricted to West Africa so the role of anthrose in physiology and pathogenesis was investigated in B. anthracis Sterne. Loss of anthrose delayed spore germination and enhanced sporulation. Spores without anthrose were phagocytized at higher rates than spores with anthrose, indicating that anthrose may serve an antiphagocytic function on the spore surface. The anthrose mutant had half the LD50 and decreased time to death (TTD) of wild type and complement B. anthracis Sterne in the A/J mouse model. Following infection, anthrose mutant bacteria were more abundant in the spleen, indicating enhanced dissemination of Sterne anthrose mutant. At low sample sizes in the A/J mouse model, the mortality of ΔantC-infected mice challenged by intranasal or subcutaneous routes was 20% greater than wild type. Competitive index (CI) studies indicated that spores without anthrose disseminated to organs more extensively than a complemented mutant. Death process modeling using mouse mortality dynamics suggested that larger sample sizes would lead to significantly higher deaths in anthrose-negative infected animals. The model was tested by infecting Galleria mellonella with spores and confirmed the anthrose mutant was significantly more lethal. Vaccination studies in the A/J mouse model showed that the human vaccine protected against high-dose challenges of the nonencapsulated Sterne-based anthrose mutant. This work begins to identify the physiologic and pathogenic consequences of convergent anthrose mutations in B. anthracis.
| S-EPMC7793302 | biostudies-literature
Project description:Single-nucleotide repeats (SNRs) are variable-number tandem repeats that display very high mutation rates. In an outbreak situation, the use of a marker system that exploits regions with very high mutation rates, such as SNRs, allows the differentiation of isolates with extremely low levels of genetic diversity. This report describes the identification and analysis of SNR loci of Bacillus anthracis. SNR loci were selected in silico, and the loci with the highest diversity were used to design and test locus-specific primers against a number of B. anthracis strains with the same multilocus variable-number tandem repeat analysis (MLVA) genotype. SNR markers that allowed strains with the same MLVA genotype to be differentiated from each other were identified. The resulting SNR marker system can be used as a molecular epidemiological tool in a natural outbreak or bioterrorism event, offering the best chance of distinguishing very closely related isolates.
| S-EPMC1393151 | biostudies-literature
Project description:BACKGROUND:Anthrax, a zoonotic disease is caused by the Gram positive bacterium Bacillus anthracis. During January 2013, an anthrax outbreak among cattle was reported in Gundlupet Taluk, neighboring Bandipur National Park and tiger reserve, India. The present study aims at the molecular identification and characterization of 12 B. anthracis isolates from this outbreak by 16S rRNA gene sequencing, screening B. anthracis specific prophages and chromosomal markers, protective antigen (pag) gene and canonical single nucleotide polymorphism (canSNP) analysis to subtype the isolates into one of the twelve globally identified clonal sub-lineages of B. anthracis. RESULTS:These isolates had identical 16S rDNA nucleotide sequences with B. anthracis specific dual peaks showing mixed base pair R (G/A) at position 1139 with visual inspection while the automated basecaller software indicated a G. Alternatively the nucleotide A at 1146 position was indicative of the 16S rDNA type 7. Multiple sequence alignment with additional 170 (16S rDNA) sequences of B. cereus sensu lato group from GenBank database revealed 28 new 16S types in addition to eleven 16S types reported earlier. The twelve B. anthracis isolates were found to harbor the four B. anthracis specific prophages (lambdaBa01, lambdaBa02, lambdaBa03, and lambdaBa04) along with its four specific loci markers (dhp 61.183, dhp 77.002, dhp 73.019, and dhp 73.017). The pag gene sequencing identified the isolates as protective antigen (PA) genotype I with phenylalanine-proline-alanine phenotype (FPA phenotype). However, sequence clustering with additional 34 pag sequences from GenBank revealed two additional missense mutations at nucleotide positions 196?bp and 869?bp of the 2294?bp pag sequence among the 5 B. cereus strains with pXO1 like plasmids. The canSNP analysis showed that the isolates belong to A.Br.Aust94 sub-lineage that is distributed geographically in countries of Asia, Africa, Europe and Australia. CONCLUSIONS:The analysis of 16S rDNA sequences reiterated the earlier findings that visual inspection of electropherogram for position 1139 having nucleotide R could be used for B. anthracis identification and not the consensus sequence from base caller. The canSNP results indicated that the anthrax outbreak among cattle was caused by B. anthracis of A.Br.Aust94 sub-lineage.
| S-EPMC7394690 | biostudies-literature
Project description:From 1997 to 2001, sequence data from 55 clinical specimens were obtained from confirmed measles cases in the United States, representing 21 outbreaks and 34 sporadic cases. Sequence analysis indicated the presence of 11 of the recognized genotypes. The most common genotypes detected were genotype D6, usually identified from imported cases from Europe, and genotype D5, associated with importations from Japan. A number of viruses belonging to genotype D4 were imported from India and Pakistan. Overall, viral genotypes were determined for 13 chains of transmission with an unknown source of virus, and seven different genotypes were identified. Therefore, the diversity of Measles virus genotypes observed in the United States from 1997 to 2001 reflected multiple imported sources of virus and indicated that no strain of measles is endemic in the United States.
| S-EPMC2732556 | biostudies-literature
Project description:Environmental reservoirs are essential in the maintenance and transmission of anthrax but are poorly characterized. The anthrax agent, Bacillus anthracis was long considered an obligate pathogen that is dormant and passively transmitted in the environment. However, a growing number of laboratory studies indicate that, like some of its close relatives, B. anthracis has some activity outside of its vertebrate hosts. Here we show in the field that B. anthracis has significant interactions with a grass that could promote anthrax spore transmission to grazing hosts. Using a local, virulent strain of B. anthracis, we performed a field experiment in an enclosure within a grassland savanna. We found that B. anthracis increased the rate of establishment of a native grass (Enneapogon desvauxii) by 50% and that grass seeds exposed to blood reached heights that were 45% taller than controls. Further we detected significant effects of E. desvauxii, B. anthracis, and their interaction on soil bacterial taxa richness and community composition. We did not find any evidence for multiplication or increased longevity of B. anthracis in bulk soil associated with grass compared to controls. Instead interactions between B. anthracis and plants may result in increased host grazing and subsequently increased transmission to hosts.
| S-EPMC4046938 | biostudies-literature
Project description:We used quantitative real-time RT-PCR to not only investigate the mRNA levels of anthrax toxin receptor 1 (ANTXR1) and 2 (ANTXR2) in the murine J774A.1 macrophage cells and different tissues of mice, but also evaluate the effect of anthrax edema toxin and Bacillus anthracis Sterne spores on the expression of mRNA of these receptors. The mRNA transcripts of both receptors were detected in J774A.1 cells and mouse tissues such as the lung, heart, kidney, spleen, stomach, jejunum, brain, skeleton muscle, and skin. The ANTXR2 mRNA level was significantly higher than that of ANTXR1 in J774A.1 cells and all tissues examined. The mRNA expression of both receptors in the lung was the highest among the tissues evaluated. Interestingly, the mRNA expression of both receptors in J774A.1 cells was upregulated by edema toxin. In addition, ANTXR mRNA expression in the lung was downregulated after subcutaneous inoculation of B. anthracis Sterne spores as well as after intranasal administration of anthrax toxin-based vaccine BioThrax. These results suggest that anthrax edema toxin and B. anthracis Sterne spore are involved in the ANTXR mRNA regulation in host cells.
| S-EPMC1973154 | biostudies-literature
Project description:In response to a bioterrorism attack in the Washington, D.C., area in October 2001, a mobile laboratory (ML) was set up in the city to conduct rapid molecular tests on environmental samples for the presence of Bacillus anthracis spores and to route samples for further culture analysis. The ML contained class I laminar-flow hoods, a portable autoclave, two portable real-time PCR devices (Ruggedized Advanced Pathogen Identification Device [RAPID]), and miscellaneous supplies and equipment to process samples. Envelopes and swab and air samples collected from 30 locations in the metropolitan area once every three days were subjected to visual examination and DNA extraction, followed by real-time PCR using freeze-dried, fluorescent-probe-based reagents. Surface swabs and air samples were also cultured for B. anthracis at the National Veterinary Service Laboratory (NVSL) in Ames, Iowa. From 24 October 2001 to 15 September 2002, 2,092 pieces of mail were examined, 405 real-time PCR assays were performed (comprising 4,639 samples), and at the NVSL 6,275 samples were subjected to over 18,000 platings. None of the PCR assays on DNA extracted from swab and air samples were positive, but viable spores were cultured from surface swabs taken from six locations in the metropolitan area in October, November, and December 2001 and February, March, and May 2002. DNA extracted from these suspected B. anthracis colonies was positive by real-time and conventional PCRs for the lethal factor, pXO1, and for capA and vrr genes; sequence analysis of the latter amplicons indicated >99% homology with the Ames, vollum, B6273-93, C93022281, and W-21 strains of B. anthracis, suggesting they arose from cross-contamination during the attack through the mail. The RAPID-based PCR analysis provided fast confirmation of suspect colonies from an overnight incubation on agar plates.
| S-EPMC152438 | biostudies-literature
Project description:Several highly attenuated spore-forming nontoxinogenic and nonencapsulated Bacillus anthracis vaccines differing in levels of expression of recombinant protective antigen (rPA) were constructed. Biochemical analyses (including electrospray mass spectroscopy and N terminus amino acid sequencing) as well as biological and immunological tests demonstrated that the rPA retains the characteristics of native PA. A single immunization of guinea pigs with 5 x 10(7) spores of one of these recombinant strains, MASC-10, expressing high levels of rPA (>/=100 microgram/ml) from a constitutive heterologous promoter induced high titers of neutralizing anti-PA antibodies. This immune response was long lasting (at least 12 months) and provided protection against a lethal challenge of virulent (Vollum) anthrax spores. The recombinant B. anthracis spore vaccine appears to be more efficacious than the vegetative cell vaccine. Furthermore, while results clearly suggest a direct correlation between the level of expression of PA and the potency of the vaccine, they also suggest that some B. anthracis spore-associated antigen(s) may contribute in a significant manner to protective immunity.
| S-EPMC98371 | biostudies-literature