16S rRNA Gene Amplicon Sequencing Data of Bacterial Community of Freshwater Sponge Lubomirskia baicalensis.

Our study was devoted to investigating the mass disease and mortality of freshwater sponges (Lubomirskiidae) in Lake Baikal. The first sights of the disease were discovered in 2011 and were associated with a shift in sponge microbial diversity. To study the microbiome, we performed sequencing of the 16S rRNA amplicon DNA extracted from the freshwater sponges.

Janthinobacterium sp. Strain SLB01 as Pathogenic Bacteria for Sponge Lubomirskia baikalensis.

Sponges (phylum Porifera) are ancient, marine and inland water, filter feeding metazoans. In recent years, diseased sponges have been increasingly occurring in marine and freshwater environments. Endemic freshwater sponges of the Lubomirskiidae family are widely distributed in the coastal zone of Lake Baikal. The strain Janthinobacterium sp. SLB01 was isolated previously from the diseased sponge Lubomirskia baikalensis (Pallas, 1776), although its pathogenicity is still unknown. The aim of this study was to confirm whether the Janthinobacterium sp. strain SLB01 is the pathogen found in Baikal sponge. To address this aim, we infected the cell culture of primmorphs of the sponge L. baikalensis with strain SLB01 and subsequently reisolated and sequenced the strain Janthinobacterium sp. PLB02. The results showed that the isolated strain has more than 99% homology with strain SLB01. The genomes of both strains contain genes vioABCDE of violacein biosynthesis and floc formation, for strong biofilm, in addition to the type VI secretion system (T6SS) as the main virulence factor. Based on a comparison of complete genomes, we showed the similarity of the studied bacterial strains of Janthinobacterium spp. with the described strain of Janthinobacterium lividum MTR. This study will help expand our understanding of microbial interactions and determine one of the causes in the development of diseases and death in Baikal sponges.

Genome Analysis of the Janthinobacterium sp. Strain SLB01 from the Diseased Sponge of the Lubomirskia baicalensis.

The strain Janthinobacterium sp. SLB01 was isolated from the diseased freshwater sponge Lubomirskia baicalensis (Pallas, 1776) and the draft genome was published previously. The aim of this work is to analyze the genome of the Janthinobacterium sp. SLB01 to search for pathogenicity factors for Baikal sponges. We performed genomic analysis to determine virulence factors, comparing the genome of the strain SLB01 with genomes of other related J. lividum strains from the environment. The strain Janthinobacterium sp. SLB01 contained genes encoding violacein, alpha-amylases, phospholipases, chitinases, collagenases, hemolysin, and a type VI secretion system. In addition, the presence of conservative clusters of genes for the biosynthesis of secondary metabolites of tropodithietic acid and marinocine was found. We present genes for antibiotic resistance, including five genes encoding various lactamases and eight genes for penicillin-binding proteins, which are conserved in all analyzed strains. Major differences were found between the Janthinobacterium sp. SLB01 and J. lividum strains in the spectra of genes for glycosyltransferases and glycoside hydrolases, serine hydrolases, and trypsin-like peptidase, as well as some TonB-dependent siderophore receptors. Thus, the study of the analysis of the genome of the strain SLB01 allows us to conclude that the strain may be one of the pathogens of freshwater sponges.

Draft Genome Sequence of the Green Microalga Chlorella sp. Strain BAC9706, Isolated from Lake Baikal, Russia.

Green algae of the phylum Chlorophyta are the most widespread autotrophic picoplankton in Lake Baika (Russia). To expand our molecular biological knowledge of these microalgae and compare them in the future with an endosymbiotic strain, we present here the draft genome sequence of Chlorella sp. strain BAC9706.

Draft Genome Sequence of Flavobacterium sp. Strain SLB02, Isolated from the Diseased Sponge Lubomirskia baicalensis.

There are significant changes in the consortium of microorganisms of freshwater Baikal sponges during their mass death, which began in 2011. The alleged cause of disease is a significant increase in the number of opportunistic microorganisms. Here, we report the draft genome sequence of Flavobacterium sp. strain SLB02.

Draft Genome Sequence of Janthinobacterium sp. Strain SLB01, Isolated from the Diseased Sponge Lubomirskia baicalensis.

The draft genome sequence of Janthinobacterium sp. strain SLB01, a violacein-producing psychrotolerant bacterium isolated from the diseased sponge Lubomirskia baicalensis, was determined. We identified five genes encoding VioA, VioB, VioC, VioD, and VioE proteins related to violacein biosynthesis that were like those identified in published Janthinobacterium lividum strains MTR and RIT308.

Characteristics of far eastern strains of tick-borne encephalitis virus.

A comparative study of biological, molecular and genetic characteristics of a collection of ten strains of tick-borne encephalitis virus (TBEV) isolated in Primorsky Krai before 1960 and stored in a lyophilized state for a prolonged period (over 65 years) is presented. The collection includes the Sofjin strain isolated from the brain of a fatal case in Primorsky Krai in 1937 and transferred to the Scientific Research Institute of Epidemiology and Microbiology (Vladivostok) in 1953. All lyophilized viral strains demonstrated great preservation and high infectious activity in the model of 2-day-old non-inbred mice. Whole-genome sequencing showed that all strains belong to the Far East TBEV subtype, comprising three clusters of Sofjin-, Oshima- and Senzhang-like strains. We show that SofjinPYB, Sofjin (Vector) and Sofjin-HO strains form a separate branch of the phylogenetic tree and are closely related to Khabarovsk-Obor-4, but not to the original Sofjin strain. The Sofjin-1953, Sofijin-Chumakov, SofjinKSY and SofjinCDC strains are genetically close to each other and can be used as reference strains for comparative analysis of the tick-borne encephalitis virus population.

Louping ill virus (LIV) in the Far East.

This study focused on finding, culturing, and identifying the biological and genetic characteristics of three louping ill virus (LIV) strains in the south of the Russian Far East. The Primorye-155-77 and Primorye-20-79 virus strains were isolated from Ixodes persulcatus ticks, and the Primorye-185-91 strain was isolated from the blood of a person after a tick bite. According to the hemagglutination and neutralization tests, Primorye-155-77, Primorye-20-79 and Primorye-185-91 had weak reactivity with antibodies in an antiserum against tick-borne encephalitis virus. In Primorye-155-77 and Primorye-20-79, the sequences of the 5' ends of the 2456-nucleotide-long viral RNA including the 5' untranslated region (UTR) and genes of the capsid protein, prM protein and envelope E protein were determined. The complete genome sequence of Primorye-185-91 was determined. The E protein gene of the Negishi strain differed from those of three analyzed strains, as there were mutations resulting in the replacement of three amino acids: Ala163Thr, Asp193Asn and Ala313Thr. The homology of Primorye-185-91 to LIV 369/T2 was 97.57 %, and to the Penrith strain, it was 98.36 %. Phylogenetic analysis showed that Primorye-155-77, Primorye-20-79 and Primorye-185-91 are related to LI/A and LI/K strains isolated in England and Scotland and to the Negishi strain; these strains have a common progenitor. Negishi-like strains were represented by one subtype of louping ill virus, i.e. the British subtype (LIV-Brit). The possibility is discussed of a single introduction of the virus to the Far Eastern region (Japan and Primorsky Krai) from a single natural locus more than 50 years ago.

The nature of replication of tick-borne encephalitis virus strains isolated from residents of the Russian Far East with inapparent and clinical forms of infection.

We describe the biological properties and molecular characteristics of complete genomes of 33 tick-borne encephalitis virus (TBEV) strains that induced different forms of infection, from inapparent to severe focal ones resulting in fatal outcome. Hemagglutinating activity of Oshima-like strains was higher at pH 5.8, while activity of Sofjin- and Senhzang-like strains were higher at pH 6.2 and 6.8, respectively. We determined susceptibility of porcine kidney (PK) cell cultures to these TBEV strains by cytopathic effect (CPE), plaque formation, and size of plaques. The clinical TBEV strains had higher virus titers both in tissue culture infectious dose 50(TCID50) and in plaque-forming unit (PFU) titers and larger plaques than the inapparent strains. A comparison of virus multiplication kinetics by PFU in culture fluid with kinetics of ELISA antigen and hemagglutinin accumulation suggested a different mechanism of interaction between these virus strains and PK cells at the initial stage of cell infection.

The relationship between the structure of the tick-borne encephalitis virus strains and their pathogenic properties.

Tick-borne encephalitis virus (TBEV) is transmitted to vertebrates by taiga or forest ticks through bites, inducing disease of variable severity. The reasons underlying these differences in the severity of the disease are unknown. In order to identify genetic factors affecting the pathogenicity of virus strains, we have sequenced and compared the complete genomes of 34 Far-Eastern subtype (FE) TBEV strains isolated from patients with different disease severity (Primorye, the Russian Far East). We analyzed the complete genomes of 11 human pathogenic strains isolated from the brains of dead patients with the encephalitic form of the disease (Efd), 4 strains from the blood of patients with the febrile form of TBE (Ffd), and 19 strains from patients with the subclinical form of TBE (Sfd). On the phylogenetic tree, pathogenic Efd strains formed two clusters containing the prototype strains, Senzhang and Sofjin, respectively. Sfd strains formed a third separate cluster, including the Oshima strain. The strains that caused the febrile form of the disease did not form a separate cluster. In the viral proteins, we found 198 positions with at least one amino acid residue substitution, of which only 17 amino acid residue substitutions were correlated with the variable pathogenicity of these strains in humans and they authentically differed between the groups. We considered the role of each amino acid substitution and assumed that the deletion of 111 amino acids in the capsid protein in combination with the amino acid substitutions R16K and S45F in the NS3 protease may affect the budding process of viral particles. These changes may be the major reason for the diminished pathogenicity of TBEV strains. We recommend Sfd strains for testing as attenuation vaccine candidates.

Molecular identification and phylogeny of Dermacentor nuttalli (Acari: Ixodidae).

Dermacentor nuttalli is an epidemiologically important tick in Palearctic Asia which transmits several infectious diseases including tularemia, North Asian tick-borne rickettsiosis, Lyme disease and tick-borne encephalitis. The genetic specificity and phylogeny of D. nuttalli from four geographic localities in Eastern Siberia were characterized using the mitochondrial (mt) 16S ribosomal RNA (rRNA) gene and internal transcribed spacer 2 (ITS2). Low genetic diversity was observed in the populations of ticks distributed from South Siberia to North China. From 11 detected mt 16S haplotypes, one was found in all populations, whereas the others were restricted to specific localities. These results suggested that the genetic structure of D. nuttalli represents integrated populations with no geographic isolation across the distribution area. The phylogenetic reconstructions inferred from the mt 16S rRNA gene and ITS2 were in agreement and showed a distinct D. nuttalli clade within a monophyletic Eurasian lineage of Dermacentor sp.

Comprehensive assessment of the genetics and virulence of tick-borne encephalitis virus strains isolated from patients with inapparent and clinical forms of the infection in the Russian Far East.

We analyzed the genetics and virulence of 35 strains of TBEV isolated from patients with different forms of the infection living in the southern Far East region of Russia. The results of moleculargenetics studies of the TBEV strains showed that most of the strains that cause inapparent infections form a single cluster (I) with the Oshima 5-10 strain from Japan on the phylogenetic tree. A comparison of the amino acid sequences of the viral polyproteins of the studied strains identified 17 amino acid residues distributed unevenly across the polyprotein that distinctly differed between the clusters of inapparent and virulent strains. We detected additional substitutions in the NS1 and NS5 proteins. These substitutions might influence the pathogenic potential of the strains. Using a model of inbred mice of different ages, we examined the virulence of these strains and showed the different pathogenic potentials of strains belonging to different clusters.

Tick-borne encephalitis virus in Eastern Siberia: complete genome characteristics.

Tick-borne encephalitis (TBE) is one of the most important arboviral diseases across Eurasia. TBE virus (TBEV) is transmitted by tick bite and causes a potentially fatal neurological infection in humans. In the Russian Federation, TBE is endemic in most regions, with 3000-5000 cases of the disease annually. To characterise TBEV in Eastern Siberia, the complete genomes of five TBEV isolates from patients with different clinical manifestations were sequenced. The results show that the Siberian and Far Eastern subtypes of TBEV cause the disease in people in Eastern Siberia. Complete genome analysis revealed an unexpectedly high genetic variability within the Siberian subtype.