Molecular investigation of the Aum Shinrikyo anthrax release in Kameido, Japan

In 1993, the Aum Shinrikyo cult aerosolized Bacillus anthracis spores over Kameido, Japan. Spore samples were obtained from the release site, cultured, and characterized by molecular genetic typing. The isolates were consistent with strain Sterne 34F2, which is used in Japan for animal prophylaxis against anthrax.

Distribution of S-layers on the surface of Bacillus cereus strains: phylogenetic origin and ecological pressure

Bacillus anthracis, Bacillus cereus and Bacillus thuringiensis have been described as members of the Bacillus cereus group but are, in fact, one species. B. anthracis is a mammal pathogen, B. thuringiensis an entomopathogen and B. cereus a ubiquitous soil bacterium and an occasional human pathogen. In two clinical isolates of B. cereus, in some B. thuringiensis strains and in B. anthracis, an S-layer has been described. We investigated how the S-layer is distributed in B. cereus, and whether phylogeny or ecology could explain its presence on the surface of some but not all strains. We first developed a simple biochemical assay to test for the presence of the S-layer. We then used the assay with 51 strains of known genetic relationship: 26 genetically diverse B. cereus and 25 non-B. anthracis of the B. anthracis cluster. When present, the genetic organization of the S-layer locus was analysed further. It was identical in B. cereus and B. anthracis. Nineteen strains harboured an S-layer, 16 of which belonged to the B. anthracis cluster. All 19 were B. cereus clinical isolates or B. thuringiensis, except for one soil and one dairy strain. These findings suggest a common phylogenetic origin for the S-layer at the surface of B. cereus strains and, presumably, ecological pressure on its maintenance.

Use of long-range repetitive element polymorphism-PCR to differentiate Bacillus anthracis strains

The genome of Bacillus anthracis is extremely monomorphic, and thus individual strains have often proven to be recalcitrant to differentiation at the molecular level. Long-range repetitive element polymorphism-PCR (LR REP-PCR) was used to differentiate various B. anthracis strains. A single PCR primer derived from a repetitive DNA element was able to amplify variable segments of a bacterial genome as large as 10 kb. We were able to characterize five genetically distinct groups by examining 105 B. anthracis strains of diverse geographical origins. All B. anthracis strains produced fingerprints comprising seven to eight bands, referred to as "skeleton" bands, while one to three "diagnostic" bands differentiated between B. anthracis strains. LR REP-PCR fingerprints of B. anthracis strains showed very little in common with those of other closely related species such as B. cereus, B. thuringiensis, and B. mycoides, suggesting relative heterogeneity among the non-B. anthracis strains. Fingerprints from transitional non-B. anthracis strains, which possessed the B. anthracis chromosomal marker Ba813, scarcely resembled those observed for any of the five distinct B. anthracis groups that we have identified. The LR REP-PCR method described in this report provides a simple means of differentiating B. anthracis strains.

A tandem repeats database for bacterial genomes: application to the genotyping of Yersinia pestis and Bacillus anthracis

BACKGROUND

Some pathogenic bacteria are genetically very homogeneous, making strain discrimination difficult. In the last few years, tandem repeats have been increasingly recognized as markers of choice for genotyping a number of pathogens. The rapid evolution of these structures appears to contribute to the phenotypic flexibility of pathogens. The availability of whole-genome sequences has opened the way to the systematic evaluation of tandem repeats diversity and application to epidemiological studies.

RESULTS

This report presents a database (http://minisatellites.u-psud.fr) of tandem repeats from publicly available bacterial genomes which facilitates the identification and selection of tandem repeats. We illustrate the use of this database by the characterization of minisatellites from two important human pathogens, Yersinia pestis and Bacillus anthracis. In order to avoid simple sequence contingency loci which may be of limited value as epidemiological markers, and to provide genotyping tools amenable to ordinary agarose gel electrophoresis, only tandem repeats with repeat units at least 9 bp long were evaluated. Yersinia pestis contains 64 such minisatellites in which the unit is repeated at least 7 times. An additional collection of 12 loci with at least 6 units, and a high internal conservation were also evaluated. Forty-nine are polymorphic among five Yersinia strains (twenty-five among three Y. pestis strains). Bacillus anthracis contains 30 comparable structures in which the unit is repeated at least 10 times. Half of these tandem repeats show polymorphism among the strains tested.

CONCLUSIONS

Analysis of the currently available bacterial genome sequences classifies Bacillus anthracis and Yersinia pestis as having an average (approximately 30 per Mb) density of tandem repeat arrays longer than 100 bp when compared to the other bacterial genomes analysed to date. In both cases, testing a fraction of these sequences for polymorphism was sufficient to quickly develop a set of more than fifteen informative markers, some of which show a very high degree of polymorphism. In one instance, the polymorphism information content index reaches 0.82 with allele length covering a wide size range (600-1950 bp), and nine alleles resolved in the small number of independent Bacillus anthracis strains typed here.

Molecular characterization of Bacillus anthracis using multiplex PCR, ERIC-PCR and RAPD

AIMS

To investigate the molecular characterization of Bacillus anthracis strains by multiplex PCR, enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) and random amplification of polymorphic DNA (RAPD).

METHODS AND RESULTS

Three primers were used to amplify the cya, cap and cereolysinAB genes in the multiplex PCR. Two distinct ERIC-PCR and RAPD fragments, which separated B. anthracis into two groups, were used as probes in Southern hybridization experiments. The probes hybridized only to the cya+ B. anthracis strains identified by the multiplex PCR. Nucleotide sequence analysis of the two cloned fragments showed they were from the pXO1 plasmid of B. anthracis.

CONCLUSION

Multiplex PCR simultaneously identified isolates of the Bacillus cereus group and the B. anthracis virulence factors. ERIC-PCR and RAPD, combined with the Southern hybridization analyses, differentiated B. anthracis strains and separated them from the closely related B. cereus group bacteria.

SIGNIFICANCE AND IMPACT OF THE STUDY

ERIC-PCR and RAPD assay could be effective in differentiating virulent from avirulent B. anthracis. Our results also show that the amplification of the large plasmids was allowed in the ERIC-PCR and RAPD assay.

Rapid recovery and identification of anthrax bacteria from the environment

Bacillus anthracis has been recognized as a highly likely biological warfare or terrorist agent. We have designed culture techniques to rapidly isolate and identify "live" anthrax from suspected environmental release. A special medium (3AT medium) allows for discrimination between closely related bacilli and non-pathogenic strains. Nitrate was found to be a primary factor influencing spore formation in Bacillus anthracis. Nitrate reduction in anthrax is not an adaptation to saprophytic environmental existence, but it is a signal to enhance environmental survival upon the death of the anthrax host, which can be mimicked in culture.

Homoduplex and heteroduplex polymorphisms of the amplified ribosomal 16S-23S internal transcribed spacers describe genetic relationships in the "Bacillus cereus group"

Bacillus anthracis, Bacillus cereus, Bacillus mycoides, Bacillus pseudomycoides, Bacillus thuringiensis, and Bacillus weihenstephanensis are closely related in phenotype and genotype, and their genetic relationship is still open to debate. The present work uses amplified 16S-23S internal transcribed spacers (ITS) to discriminate between the strains and species and to describe the genetic relationships within the "B. cereus group," advantage being taken of homoduplex-heteroduplex polymorphisms (HHP) resolved by polyacrylamide gel electrophoresis and silver staining. One hundred forty-one strains belonging to the six species were investigated, and 73 ITS-HHP pattern types were distinguished by MDE, a polyacrylamide matrix specifically designed to resolve heteroduplex and single-strand conformation polymorphisms. The discriminating bands were confirmed as ITS by Southern hybridization, and the homoduplex or heteroduplex nature was identified by single-stranded DNA mung bean nuclease digestion. Several of the ITS-HHP types corresponded to specific phenotypes such as B. anthracis or serotypes of B. thuringiensis. Unweighted pair group method arithmetic average cluster analysis revealed two main groups. One included B. mycoides, B. weihenstephanensis, and B. pseudomycoides. The second included B. cereus and B. thuringiensis, B. anthracis appeared as a lineage of B. cereus.

Bacillus anthracis diversity in Kruger National Park

The Kruger National Park (KNP), South Africa, has a recorded history of periodic anthrax epidemics causing widespread disease among wild animals. Bacillus anthracis is the causative agent of anthrax, a disease primarily affecting ungulate herbivores. Worldwide there is little diversity among B. anthracis isolates, but examination of variable-number tandem repeat (VNTR) loci has identified six major clones, with the most dissimilar types split into the A and B branches. Both the A and B types are found in southern Africa, giving this region the greatest genetic diversity of B. anthracis worldwide. Consequently, southern Africa has been hypothesized to be the geographic origin of B. anthracis. In this study, we identify the genotypic types of 98 KNP B. anthracis isolates using multiple-locus VNTR analysis. Two major types are evident, the A branch and the B branch. The spatial and temporal distribution of the different genotypes indicates that anthrax epidemic foci are independent, though correlated through environmental cues. Kruger B isolates were found on significantly higher-calcium and higher-pH soils than were Kruger type A. This relationship between genotype and soil chemistry may be due to adaptive differences among divergent anthrax strains. While this association may be simply fortuitous, adaptation of A types to diverse environmental conditions is consistent with their greater geographic dispersal and genetic dissimilarity.

Comparison of PCR-RFLP, ribotyping and ERIC-PCR for typing Bacillus anthracis and Bacillus cereus strains

PCR-RFLP analysis of the vrrA gene and cerAB gene was used to investigate the genomic diversity in 21 strains of Bacillus anthracis and 28 strains of Bacillus cereus, and was compared with results obtained by ribotyping and enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) analysis. VrrA-typing divided the B. anthracis into four groups. Except for one Pasteur vaccine strain, the vrrA PCR-RFLP profiles of the B. anthracis were separated into three groups, which were different from those of the B. cereus strains. Ribotyping separated the B. anthracis isolates into seven ribotypes, and a common fragment of an approximately 850 bp band from the ERIC-PCR fingerprints separated most B. anthracis strains into two groups. VrrA/cerAB PCR-RFLP, ribotyping and ERIC-PCR generated 18, 22 and 23 types, respectively, from B. cereus strains. The results suggest that a combination of all three methods provides a high resolution typing method for B. anthracis and B. cereus. Compared with ribotyping and ERIC-PCR, PCR-RFLP is simple to perform and has potential as a rapid method for typing and discriminating B. anthracis strains from other B. cereus group bacteria.

Phenotypic and genotypic comparisons of 23 strains from the Bacillus cereus complex for a selection of known and putative B. thuringiensis virulence factors

Sixteen Bacillus thuringiensis, four Bacillus cereus and three Bacillus anthracis isolates were screened for a selection of known and putative B. thuringiensis virulence factors. PCR primers were designed to detect genes for phosphatidylcholine specific phospholipase C, phosphatidylinositol specific phospholipase C, immune inhibitor A, vegetative insecticidal protein 3A, a protein proposed to be involved in capsule synthesis, a newly identified Ser/Thr kinase homologue and enterotoxin entS. Motility, the presence of flagella, haemolysis, chitinase and lecithinase production were also evaluated. The widely varying profiles of the 23 strains from the complex provide a pool of different genotypes that can help to identify factors involved in pathogenicity.

Bacillus anthracis, Bacillus cereus, and Bacillus thuringiensis--one species on the basis of genetic evidence

Bacillus anthracis, Bacillus cereus, and Bacillus thuringiensis are members of the Bacillus cereus group of bacteria, demonstrating widely different phenotypes and pathological effects. B. anthracis causes the acute fatal disease anthrax and is a potential biological weapon due to its high toxicity. B. thuringiensis produces intracellular protein crystals toxic to a wide number of insect larvae and is the most commonly used biological pesticide worldwide. B. cereus is a probably ubiquitous soil bacterium and an opportunistic pathogen that is a common cause of food poisoning. In contrast to the differences in phenotypes, we show by multilocus enzyme electrophoresis and by sequence analysis of nine chromosomal genes that B. anthracis should be considered a lineage of B. cereus. This determination is not only a formal matter of taxonomy but may also have consequences with respect to virulence and the potential of horizontal gene transfer within the B. cereus group.

Multiple-locus variable-number tandem repeat analysis reveals genetic relationships within Bacillus anthracis

Bacillus anthracis is one of the most genetically homogeneous pathogens described, making strain discrimination particularly difficult. In this paper, we present a novel molecular typing system based on rapidly evolving variable-number tandem repeat (VNTR) loci. Multiple-locus VNTR analysis (MLVA) uses the combined power of multiple alleles at several marker loci. In our system, fluorescently labeled PCR primers are used to produce PCR amplification products from eight VNTR regions in the B. anthracis genome. These are detected and their sizes are determined using an ABI377 automated DNA sequencer. Five of these eight loci were discovered by sequence characterization of molecular markers (vrrC(1), vrrC(2), vrrB(1), vrrB(2), and CG3), two were discovered by searching complete plasmid nucleotide sequences (pXO1-aat and pXO2-at), and one was known previously (vrrA). MLVA characterization of 426 B. anthracis isolates identified 89 distinct genotypes. VNTR markers frequently identified multiple alleles (from two to nine), with Nei's diversity values between 0.3 and 0.8. Unweighted pair-group method arithmetic average cluster analysis identified six genetically distinct groups that appear to be derived from clones. Some of these clones show worldwide distribution, while others are restricted to particular geographic regions. Human commerce doubtlessly has contributed to the dispersal of particular clones in ancient and modern times.

Identification of Bacillus anthracis strains in China

As part of a project to establish a reference strain collection, phenotypic, biochemical and genetic analyses were carried out on 84 strains of Bacillus anthracis, 81 of them of Chinese origin from various sources. Particular differences from reports on isolates of other origins were the possession of fimbriae and single polar flagella with consequent motility in 77, self-agglutination by 64 and failure to ferment maltose in 60 of the Chinese strains. The findings were considered to be of significance to identification, classification and evolution of B. anthracis.

Definitive identification of Bacillus anthracis--a review

The word 'problem' is seen with some frequency in relation to clear differentiation between Bacillus anthracis and B. cereus. In fact, although the close relationship of these two species is undisputed, it is only in the case of a few borderline isolates, rarely encountered in practice, that any sort of identification problem exists. Until recently this was only important to the taxonomist who found it unsatisfactory not to be able to identify definitively such isolates. To most others, if the isolate was unable to produce anthrax in a laboratory animal, it was discarded as irrelevant without being named, or it was called B. cereus or given a name such as B. anthracis similis, or even a totally unrelated name. More recently, in view of the new light in which B. anthracis is increasingly seen, resulting from its putative association with bioaggression, clear identification has become a more critical issue. This paper reviews the current state of the art and suggests the way forward for the future.

The Ba813 chromosomal DNA sequence effectively traces the whole Bacillus anthracis community

Plasmid genes that are responsible for virulence of Bacillus anthracis are important targets for the DNA-based detection of anthrax. We evaluated the distribution of the Ba813 chromosomal DNA sequence (Ba813) within closely related Bacillus species. Ba813 was systematically identified from 47 strains or isolates of B. anthracis tested, thus indicating its reliability as a tracer for that species. From the 60 strains of closely related Bacillus spp. examined, three bona fide B. cereus and one bona fide B. thuringiensis were found to harbour Ba813. This marker was also detected in Bacillus sp. isolates that were present at high levels in soil samples collected in a place where an anthrax outbreak had occurred. The significance and the possible function of the Ba813 locus is discussed.

Polymerase chain reaction-ELISA to detect Bacillus anthracis from soil samples-limitations of present published primers

A polymerase chain reaction (PCR)-ELISA technique to detect Bacillus anthracis from soil samples has been developed. The application of streptavidine-coated microtitre plates as well as plates covered with covalently linked oligonucleotides as catching probes led to a test sensitivity of about 100 fg pure genomic DNA or of less than 10 spores seeded into 100 g soil material. Some non-suspicious soil samples collected from different locations yielded positive results with presently published primers or probes targeting the B or C gene of pX02 and with primers targeting the chromosomal sequence B813. The former PCR products were sequenced. The number and mode of base exchanges led to the assumption that there will exist at least one unknown soil organism with high similarity within highly conserved capsule-encoding genes.

Fluorescent detection techniques for real-time multiplex strand specific detection of Bacillus anthracis using rapid PCR

Speed is a key area in our development of PCR assays for Bacillus anthracis. We believe that the strand specific detection of amplicons within 10 min is a realistic goal and that this will be achieved through fluorescent in-tube assays. We have used the Idaho LightCycler to study and develop candidate assays for B. anthracis. New strand specific fluorescent methods have been developed and a number of formats have been studied for speed and sensitivity. Internal controls have been developed as a method of improving our assay confidence. In this communication we will introduce the field of rapid PCR whilst discussing previous work in the areas described above, the development of our own rapid assay and a novel internal control system for B. anthracis. This work used PCR assays and hardware that are either commercially available, or have been previously described in open literature publications.

PlcR is a pleiotropic regulator of extracellular virulence factor gene expression in Bacillus thuringiensis

Members of the Bacillus cereus group (B. anthracis, B. cereus, B. mycoides and B. thuringiensis) are well-known pathogens of mammals (B. anthracis and B. cereus) and insects (B. thuringiensis). The specific diseases they cause depend on their capacity to produce specific virulence factors, such as the lethal toxin of B. anthracis and the Cry toxins of B. thuringiensis. However, these Bacillus spp. also produce a variety of proteins, such as phospholipases C, which are known to act as virulence factors in various pathogenic bacteria. Few genes encoding these virulence factors have been characterized in pathogenic Bacillus spp. and little is known about the regulation of their expression. We had previously reported that in B. thuringiensis expression of the phosphatidylinositol-specific phospholipase C gene is regulated by the transcriptional activator PlcR. Here we report the identification of several extracellular virulence factor genes by the virtue of their PlcR-regulated expression. These PlcR-regulated genes encode degradative enzymes, cell-surface proteins and enterotoxins. The PlcR-regulated genes are widely dispersed on the chromosome and therefore do not constitute a pathogenic island. Analysis of the promoter region of the PlcR-regulated genes revealed the presence of a highly conserved palindromic region (TATGNAN4TNCATA), which is presumably the specific recognition target for PlcR activation. We found that the plcR gene is also present in and probably restricted to all the members of the B. cereus group. However, although the polypeptide encoded by the B. cereus PlcR gene is functionally equivalent to the B. thuringiensis regulator, the polypeptide encoded by the B. anthracis gene is truncated and not active as a transcriptional activator. PlcR is the first example described of a pleiotropic regulator involved in the control of extracellular virulence factor expression in pathogenic Bacillus spp. These results have implications for the taxonomic relationships among members of the B. cereus group, the virulence properties of these bacteria and the safety of B. thuringiensis-based biopesticides.

A randomly amplified polymorphic DNA marker specific for the Bacillus cereus group is diagnostic for Bacillus anthracis

Aiming to develop a DNA marker specific for Bacillus anthracis and able to discriminate this species from Bacillus cereus, Bacillus thuringiensis, and Bacillus mycoides, we applied the randomly amplified polymorphic DNA (RAPD) fingerprinting technique to a collection of 101 strains of the genus Bacillus, including 61 strains of the B. cereus group. An 838-bp RAPD marker (SG-850) specific for B. cereus, B. thuringiensis, B. anthracis, and B. mycoides was identified. This fragment included a putative (366-nucleotide) open reading frame highly homologous to the ypuA gene of Bacillus subtilis. The restriction analysis of the SG-850 fragment with AluI distinguished B. anthracis from the other species of the B. cereus group.

Molecular characterization of Bacillus strains involved in outbreaks of anthrax in France in 1997

Outbreaks of anthrax zoonose occurred in two regions of France in 1997. Ninety-four animals died, and there were three nonfatal cases in humans. The diagnosis of anthrax was rapidly confirmed by bacteriological and molecular biological methods. The strains of Bacillus anthracis in animal and soil samples were identified by a multiplex PCR assay. They all belonged to the variable-number tandem repeat (VNTR) group (VNTR)3. A penicillin-resistant strain was detected. Nonvirulent bacilli related to B. anthracis, of all VNTR types, were also found in the soil.

Construction of phylogenetic tree based on G + C contents in DNA and 16S rRNA sequences: example for group 1 of genus Bacillus

The applicability of the G + C content in DNA in the construction of phylogenetic tree was studied. The group 1 of the genus Bacillus was selected as an object for study. Statistically reliable correlation between evolutionary distances of 16S rRNA sequences (Ei) and parameter Pi named as "GC evolutionary distance" was shown. The value of Pi is the difference between the G + C content in DNA of two species branching from one phylogenetic line. The coefficient of correlation between Ei and Pi equals 0.97 for the representatives of group 1, including Bacillus anthracis, B. cereus, B. circulans, B. firmus, B. lautus, and B. subtilis. Phylogenetic studies of the G + C content in DNA in the genus Bacillus, group 1 representatives has shown that this character can be used in molecular systematics and phylogeny as additional data altogether with the data on 16S rRNA sequences.

Molecular evolution and diversity in Bacillus anthracis as detected by amplified fragment length polymorphism markers

Bacillus anthracis causes anthrax and represents one of the most molecularly monomorphic bacteria known. We have used AFLP (amplified fragment length polymorphism) DNA markers to analyze 78 B. anthracis isolates and six related Bacillus species for molecular variation. AFLP markers are extremely sensitive to even small sequence variation, using PCR and high-resolution electrophoresis to examine restriction fragments. Using this approach, we examined ca. 6.3% of the Bacillus genome for length mutations and ca. 0.36% for point mutations. Extensive variation was observed among taxa, and both cladistic and phenetic analyses were used to construct a phylogeny of B. anthracis and its closest relatives. This genome-wide analysis of 357 AFLP characters (polymorphic fragments) indicates that B. cereus and B. thuringiensis are the closest taxa to B. anthracis, with B. mycoides slightly more distant. B. subtilis, B. polymyxa, and B. stearothermophilus shared few AFLP markers with B. anthracis and were used as outgroups to root the analysis. In contrast to the variation among taxa, only rare AFLP marker variation was observed within B. anthracis, which may be the most genetically uniform bacterial species known. However, AFLP markers did establish the presence or absence of the pXO1 and pXO2 plasmids and detected 31 polymorphic chromosomal regions among the 79 B. anthracis isolates. Cluster analysis identified two very distinct genetic lineages among the B. anthracis isolates. The level of variation and its geographic distribution are consistent with a historically recent African origin for this pathogenic organism. Based on AFLP marker similarity, the ongoing anthrax epidemic in Canada and the northern United States is due to a single strain introduction that has remained stable over at least 30 years and a 1,000-mile distribution.

Pyrolysis mass spectrometry studies on Bacillus anthracis, Bacillus cereus and their close relatives

Pyrolysis mass spectrometry was used to examine strains of B. anthracis, of B. cereus, of B.cereus either proven to cause emetic illness or connected with outbreaks of emetic food poisoning and of B.thuringiensis. Analysis of the data-set for all strains allowed differentiation between B.anthracis, the emetic B.cereus and B.thuringiensis but B.cereus strains could not be clearly discriminated. Removal of data for the B.thuringiensis and the emetic B.cereus strains, followed by re-analysis, allowed clear separation of the B. anthracis and B. cereus groups. Furthermore, PyMS was found to be capable of discriminating between some strains of B.anthracis, and demonstrating sub-groupings of others. This work provides further evidence of the ability of PyMS to distinguish rapidly between very closely related organisms and indicates its potential in epidemiology.

Differentiation of Bacillus anthracis and other 'Bacillus cereus group' bacteria using IS231-derived sequences

Sequences based on the conserved 20 bp inverted repeat of IS231 variants were used as polymerase chain reaction-based fingerprinting primers of the member species of the Bacillus cereus group (B. anthracis, B. cereus, B. thuringiensis and B. mycoides), because of their close association with transposons, principally Tn4430 in B. thuringiensis. Fingerprints of B. anthracis were simple, and specifically allowed its identification and sub-differentiation from other members of the group. Fingerprints for B. cereus were strain-specific; those for B. thuringensis gave a 1650 bp product, characteristic of IS231 variants A-F. The same reaction conditions gave one or two bands for both B. anthracis and B. cereus that differed by restriction endonuclease mapping from the B. thuringiensis PCR product and established IS231 restriction maps; this does not preclude some kind of relationship between these products and IS231.

Comparative analysis of the 16S to 23S ribosomal intergenic spacer sequences of Bacillus thuringiensis strains and subspecies and of closely related species

Bacillus thuringiensis spacer regions between the 16S and 23S rRNAs were amplified with conserved primers, designated 19-mer and 23-mer primers. A spacer region of 144 bp was determined for all of 6 B. thuringiensis strains, 7 B. thuringiensis subspecies, and 11 B. thuringiensis field isolates, as well as for the closely related species Bacillus cereus and Bacillus anthracis. Computer analysis and alignment of nucleotide sequences identified three mutations and one deletion in the intergenic spacer region (ISR) of B. thuringiensis subsp. kurstaki HD-1 when compared with ISR sequences from other subspecies. The same differences were identified between the ISR of B. thuringiensis strains and the ISR of B. cereus and B. anthracis. These minor differences do not seem to be sufficient to allow the design of a species-specific oligonucleotide probe.

Non-toxigenic derivatives of the Ames strain of Bacillus anthracis are fully virulent for mice: role of plasmid pX02 and chromosome in strain-dependent virulence

The toxin-encoding plasmid pX01 and capsule-associated plasmid pX02 are required for full virulence of Bacillus anthracis in some animals. However, the non-toxigenic pX01-cured derivatives of certain anthrax strains are not completely attenuated for mice, and their virulence is strain-dependent. The strain-related differences were partially associated with plasmid pX02 as demonstrated by pX02 transductants of the attenuated vaccine strain UM23-1 cured of pX01. To determine the virulence of non-toxigenic variants of virulent strains, we isolated pX01- derivatives of the Vollum 1B strain and the more 'vaccine-resistant' Ames strain which carried pX02 from either Ames or Vollum 1B. The 50% lethal dose (LD50) values of the derivatives of both strains which carried the Ames pX02 were not significantly different from the LD50s of the pX01+ pX02+ strains (and were lower than those of pX01+ pX02- strains). pX02+ derivatives of strain UM23-1 were less virulent than the comparable Ames and Vollum 1B strain derivatives, emphasizing a role for chromosomal loci in the virulence of the latter two strains. Non-toxigenic isolates which carried the Ames pX02 were more virulent for CBA/J mice than those with Vollum 1B pX02, and the differences were mouse strain-dependent. The pX01- pX02+ strains multiplied and achieved high concentrations systemically.

Comparative analysis of Bacillus anthracis, Bacillus cereus, and related species on the basis of reverse transcriptase sequencing of 16S rRNA

The primary structures of the 16S rRNAs of Bacillus anthracis, Bacillus cereus, Bacillus mycoides, and Bacillus thuringiensis were determined by using the reverse transcription-dideoxy sequencing method. All of the strains exhibited very high levels of sequence similarity (greater than 99%) that were consistent with the close relationships shown by previous DNA hybridization studies. The sequences of B. anthracis Sterne and B. cereus emetic strain NCTC 11143 were found to be identical for a continuous stretch of 1,446 bases and differed from the sequence of B. cereus NCDO 1771T (T = type strain) by only a single nucleotide. The 16S rRNA sequences of B. mycoides and B. thuringiensis differed from each other and from the sequences of B. anthracis and B. cereus by four to nine nucleotides.

[Study on the discrimination of bacteria by gas chromatographic profiles of cellular monosaccharides]

A procedure for obtaining gas chromatographic (GC) profiles of bacterial cellular monosaccharides was described. Some of the unknown component peaks in these profiles were identified. And, based on the complete linkage cluster analysis with the Euclidean distance coefficient, the interpretation of the resulting cellular monosaccharides of bacteria were performed by mini-computer. By means of this method, the discrimination of 5 species (24 strains) of aerobic endospore-forming bacteria. The results showed that there were defined differences between the profiles of cellular monosaccharides of B. anthracis and B. cereus. This procedure has provided a useful method for the classification and identification of microorganisms, for their physiological and biochemical studies, and for studies on their subcellular components.

[The use of plasmid screening for the differentiation of Bacillus anthracis strains from closely related species of soil bacilli]

B. anthracis virulent and vaccine strains differ from the strains of species closely related to B. anthracis, such as B. cereus and B. thuringiensis, in their plasmid spectrum. The use of their plasmid spectrum. The use of the plasmid analysis of the strain is recommended for laboratory practice as the main differential diagnostic test.

Virulence and immunogenicity in experimental animals of Bacillus anthracis strains harbouring or lacking 110 MDa and 60 MDa plasmids

A comparative study was made of the virulence and immunogenicity in mice or guinea pigs of Bacillus anthracis strains harbouring 110 MDa and/or 60 MDa plasmids. Strains cured of the 110 MDa or the 60 MDa plasmid were more than 100-fold less virulent to mice than were the parental strains harbouring these plasmids. Guinea-pigs immunized with plasmid-free derivatives of the non-encapsulated vaccine strain 34F2 showed no resistance to challenge with strain 17JB, which harbours both 110 MDa and 60 MDa plasmids, suggesting that the derivative strains had lost their immunizing ability against anthrax.

Identification of Bacillus anthracis by API tests

API and morphological tests were examined for their ability to distinguish between 37 Bacillus anthracis strains (virulent and avirulent) and 194 strains of closely related Bacillus species (B. cereus, B. mycoides and B. thuringiensis). In addition, 34 strains of B. anthracis and four of B. cereus were tested by several other methods that included capsule formation, ability to grow on a selective medium, and sensitivity to phage. It was found that virulent strains of B. anthracis were easily separated from the closely related Bacillus species by most of the test methods; but separation of slightly virulent and avirulent strains of B. anthracis from the closely related species could be done only by API and phage-sensitivity tests.

Enzyme-linked lectinosorbent assay (ELLA) for detecting Bacillus anthracis

An enzyme-linked lectinosorbent assay (ELLA) has been developed for the rapid identification of Bacillus anthracis. Using two different lectin-conjugates, the ELLA test can differentiate Bacillus anthracis from closely related species, such as Bacillus cereus and Bacillus cereus var. mycoides, in approximately two hours. In addition to having high specificity, the test can also detect small numbers of the bacterium.

Glycosidase activities of Bacillus anthracis

Bacillus anthracis could be distinguished from the taxonomically related species B. cereus, B. mycoides, and B. thuringiensis by a comparison of glycosidase activities. All the bacilli tested possessed alpha-glucosidase activity, as evidenced by the hydrolysis of p-nitrophenyl-alpha-D-glucoside. In B. anthracis, the glucosidase activity could be enhanced by the addition of agents which damage cellular surface structures. Treatment of B. anthracis strains with toluene. Triton X-100, or mutanolysin or cellular disruption by sonication resulted in higher rates of alpha-glucoside hydrolysis than were accomplished by cells suspended in buffer. It is suggested that intact B. anthracis cells have a limited permeability to the glucosidase substrate. In contrast to the results obtained for B. anthracis, Triton X-100 markedly diminished the enzymatic hydrolysis of p-nitrophenyl-alpha-D-glucoside by strains of B. cereus, B. mycoides, and B. thuringiensis. Triton X-100 also enhanced the alpha-maltosidase activity of B. anthracis but not that of the other bacilli. B. mycoides possessed an apparently inducible N-acetylglucosaminidase although the enzyme was absent in B. anthracis. The glucosaminidase was inducible in the presence of p-nitrophenyl-N-acetylglucosamine in the absence of conventional nitrogen sources. Chloramphenicol prevented the induction of the glucosaminidase in B. mycoides. In several B. cereus and all B. thuringiensis strains, the glucosaminidase was constitutive. The results suggest a means for the rapid laboratory differentiation of B. anthracis from other closely related bacilli. Assays for alpha-glucosidase and alpha-maltosidase, in the presence and absence of Triton X-100, can be used to distinguish B. anthracis from B. cereus, B. mycoides, and B. thuringiensis. Similarly, the hydrolysis of p-nitrophenyl-beta-N-acetylglucosamine induced by B. mycoides but not by B. anthracis provides an additional means for differentiating these similar bacilli.

Differentiation of Bacillus anthracis and other Bacillus species by lectins

Bacillus anthracis was agglutinated by several lectins, including those from Griffonia simplicifolia, Glycine max, Abrus precatorius, and Ricinus communis. Some strains of Bacillus cereus var. mycoides (B. mycoides) were strongly reactive with the lectin from Helix pomatia and weakly reactive with the G. max lectin. The differential interactions between Bacillus species and lectins afforded a means of distinguishing B. anthracis from other bacilli. B. cereus strains exhibited heterogeneity with respect to agglutination patterns by lectins but could readily be differentiated from B. anthracis and the related B. mycoides. Spores of B. anthracis and B. mycoides retained lectin receptors, although the heating of spores or vegetative cells at 100 degrees C resulted in a decrease in their ability to be specifically agglutinated. Fluorescein-conjugated lectin of G. max stained vegetative cells of B. anthracis uniformly, suggesting that the distribution of lectin receptors was continuous over the entire cellular surface. B. anthracis cells grown under conditions to promote the production of capsular poly(D-glutamyl peptide) were also readily agglutinated by the lectins, suggesting that the lectin reactive sites penetrate the polypeptide layer. Trypsin, subtilisin, lysozyme, and mutanolysin did not modify the reactivity of B. anthracis with the G. max agglutinin, although the same enzymes markedly diminished the interaction between the lectin and B. mycoides. Because the lectins which interact with B. anthracis are specific for alpha-D-galactose or 2-acetamido-2-deoxy-alpha-D-galactose residues, it is likely that the bacteria possess cell surface polymers which contain these sugars. Lectins may prove useful in the laboratory identification of B. anthracis and possibly other pathogenic Bacillus species, such as B. cereus.

Quantitative immunofluorescence studies of the serology of Bacillus anthracis spores

A fluorescein-conjugated antibody against formalin-inactivated spores of Bacillus anthracis Vollum reacted only weakly with a variety of Bacillus species in microfluorometric immunofluorescence assays. A conjugated antibody against spores of B. anthracis Sterne showed little affinity for spores of several B. anthracis isolates including B. anthracis Vollum, indicating that more than one anthrax spore serotype exists.

Agar diffusion method for the differentiation of Bacillus anthracis

A method was developed for identification of Bacillus anthracis based on elaboration of protective antigen by individual colonies and its detection by double-diffusion precipitation in agar plates.