New Research on the Bacillus anthracis Genetic Diversity in Siberia.

Anthrax is a particularly dangerous infection of humans and ungulates caused by the Gram-positive spore-forming bacterium Bacillus anthracis. The highly monomorphic and clonal species B. anthracis is commonly divided into three main lineages, A, B, and C, which in turn are divided into several canSNP groups. We report here a phylogenetic analysis based on the whole-genome sequence (WGS) data of fifteen strains isolated predominantly in Siberia or Central and Southern Russia. We confirm the wide distribution of the cluster of strains of the B.Br.001/002 group, endemic to the Russian Arctic, which is also present in the steppe zone of Southern Siberia. We characterize additional branches within the major A.Br.001/002 polytomy comprising the A.Br.Ames and A.Br.Sterne lineages, one of which is identified in the Arctic.

New formulation of a recombinant anthrax vaccine stabilised with structurally modified plant viruses.

Anthrax is a disease caused by Bacillus anthracis. The most promising approach to the development of anthrax vaccine is use of the anthrax protective antigen (PA). At the same time, recombinant PA is a very unstable protein. Previously, the authors have designed a stable modified recombinant anthrax protective antigen with inactivated proteolytic sites and substituted deamidation sites (rPA83m). As a second approach to recombinant PA stabilisation, plant virus spherical particles (SPs) were used as a stabiliser. The combination of these two approaches was shown to be the most effective. Here, the authors report the results of a detailed study of the stability, immunogenicity and protectiveness of rPA83m + SPs compositions. These compositions were shown to be stable, provided high anti-rPA83m antibody titres in guinea pigs and were able to protect them from a fully virulent 81/1 Bacillus anthracis strain. Given these facts, the formulation of rPA83m + SPs compositions is considered to be a prospective anthrax vaccine candidate.

Some Peculiarities of Anthrax Epidemiology in Herbivorous and Carnivorous Animals.

Anthrax is an especially dangerous zooanthroponosis caused by the Gram-positive spore-forming bacterium Bacillus anthracis. A notable feature of this disease is the difference in susceptibility to it among different groups of animals. Anthrax primarily affects herbivorous ungulate mammals; they are easily infected, and their disease often leads to rapid, even sudden, death. However, predators and scavengers are extremely resistant to anthrax, and if they become infected, they usually become mildly ill. As the result of the increased sensitivity of ungulates to anthrax and the possibility of disease transmission from them to humans, most studies of anthrax have focused on the diagnosis, prevention, and treatment of infection in farm animals and humans. The issues of anthrax in other animals, such as predators, and the peculiarities of anthrax epidemiology in wild ungulates have not been sufficiently detailed in the literature. In this article, we provide a review of literature sources that describe the differential susceptibility to infection of various groups of animals to anthrax and some epidemiological features of anthrax in animals that are not the main hosts of B. anthracis.

Using a Syrian (Golden) Hamster Biological Model for the Evaluation of Recombinant Anthrax Vaccines.

In this paper, we demonstrate that a Syrian hamster biological model can be applied to the study of recombinant anthrax vaccines. We show that double vaccination with recombinant proteins, such as protective antigen (PA) and fusion protein LF1PA4, consisting of lethal factor I domain (LF) and PA domain IV, leads to the production of high titers of specific antibodies and to protection from infection with the toxicogenic encapsulated attenuated strain B. anthracis 71/12. In terms of antibody production and protection, Syrian hamsters were much more comparable to guinea pigs than mice. We believe that Syrian hamsters are still underestimated as a biological model for anthrax research, and, in some cases, they can be used as a replacement or at least as a complement to the traditionally used mouse model.

Sequence Variability of pXO1-Located Pathogenicity Genes of Bacillus anthracis Natural Strains of Different Geographic Origin.

The main pathogenic factor of Bacillus anthracis is a three-component toxin encoded by the pagA, lef, and cya genes, which are located on the pXO1 plasmid. The atxA gene, which encodes the primary regulator of pathogenicity factor expression, is located on the same plasmid. In this work, we evaluated the polymorphism of the pagA, lef, cya, and atxA genes for 85 B. anthracis strains from different evolutionary lineages and canSNP groups. We have found a strong correlation of 19 genotypes with the main evolutionary lineages, but the correlation with the canSNP group of the strain was not as strong. We have detected several genetic markers indicating the geographical origin of the strains, for example, their source from the steppe zone of the former USSR. We also found that strains of the B.Br.001/002 group caused an anthrax epidemic in Russia in 2016 and strains isolated during paleontological excavations in the Russian Arctic have the same genotype as the strains of the B.Br.CNEVA group circulating in Central Europe. This data could testify in favor of the genetic relationship of these two groups of strains and hypothesize the ways of distribution of their ancestral forms between Europe and the Arctic.

The Comparative Virulence of Francisella tularensis Subsp. mediasiatica for Vaccinated Laboratory Animals.

Tularemia is a severe infectious disease caused by the Gram-negative bacteria Fracisella tularensis. There are four subspecies of F.tularensis: holarctica, tularensis, mediasiatica, and novicida, which differ in their virulence and geographic distribution. One of them, subsp. mediasiatica remains extremely poorly studied, primarily due to the fact that it is found only in the sparsely populated regions of Central Asia and Russia. In particular there is little information in the literature on the virulence and pathogenicity of subsp. mediasiatica. In the present article, we evaluated the comparative virulence of subsp. mediasiatica in vaccinated laboratory animals which we infected with virulent strains: subsp. mediasiatica 678, subsp. holarctica 503, and subsp. tularensis SCHU within 60 to 180 days after vaccination. We found that subsp. mediasiatica is comparable in pathogenicity in mice with subsp. tularensis and in guinea pigs with subsp. holarctica. We also found that the live vaccine does not fully protect mice from subsp. mediasiatica but completely protects guinea pigs for at least six months. In general, our data suggest that subsp. mediasiatica occupies an intermediate position in virulence between spp. tularensis and holarctica.

Draft Genome Sequences of Three Francisella tularensis subsp. mediasiatica Strains Isolated in the Altai Territory, Russian Federation.

We report the draft genome sequences of three Francisella tularensis subsp. mediasiatica strains isolated in the Altai Territory, Russian Federation.

Insights from Bacillus anthracis strains isolated from permafrost in the tundra zone of Russia.

This article describes Bacillus anthracis strains isolated during an outbreak of anthrax on the Yamal Peninsula in the summer of 2016 and independently in Yakutia in 2015. A common feature of these strains is their conservation in permafrost, from which they were extracted either due to the thawing of permafrost (Yamal strains) or as the result of paleontological excavations (Yakut strains). All strains isolated on the Yamal share an identical genotype belonging to lineage B.Br.001/002, pointing to a common source of infection in a territory over 250 km in length. In contrast, during the excavations in Yakutia, three genetically different strains were recovered from a single pit. One strain belongs to B.Br.001/002, and whole genome sequence analysis showed that it is most closely related to the Yamal strains in spite of the remoteness of Yamal from Yakutia. The two other strains contribute to two different branches of A.Br.008/011, one of the remarkable polytomies described so far in the B. anthracis species. The geographic distribution of the strains belonging to A.Br.008/011 is suggesting that the polytomy emerged in the thirteenth century, in combination with the constitution of a unified Mongol empire extending from China to Eastern Europe. We propose an evolutionary model for B. anthracis recent evolution in which the B lineage spread throughout Eurasia and was subsequently replaced by the A lineage except in some geographically isolated areas.

Russian isolates enlarge the known geographic diversity of Francisella tularensis subsp. mediasiatica.

Francisella tularensis, a small Gram-negative bacterium, is capable of infecting a wide range of animals, including humans, and causes a plague-like disease called tularemia-a highly contagious disease with a high mortality rate. Because of these characteristics, F. tularensis is considered a potential agent of biological terrorism. Currently, F. tularensis is divided into four subspecies, which differ in their virulence and geographic distribution. Two of them, subsp. tularensis (primarily found in North America) and subsp. holarctica (widespread across the Northern Hemisphere), are responsible for tularemia in humans. Subsp. novicida is almost avirulent in humans. The fourth subspecies, subsp. mediasiatica, is the least studied because of its limited distribution and impact in human health. It is found only in sparsely populated regions of Central Asia. In this report, we describe the first focus of naturally circulating F. tularensis subsp. mediasiatica in Russia. We isolated and characterized 18 strains of this subspecies in the Altai region. All strains were highly virulent in mice. The virulence of subsp. mediasiatica in a vaccinated mouse model is intermediate between that of subsp. tularensis and subsp. holarctica. Based on a multiple-locus variable number tandem repeat analysis (MLVA), we show that the Altaic population of F. tularensis subsp. mediasiatica is genetically distinct from the classical Central Asian population, and probably is endemic to Southern Siberia. We propose to subdivide the mediasiatica subspecies into three phylogeographic groups, M.I, M.II and M.III.