Study of Viral Coinfection of the Ticks Feeding on Humans in a Natural Focus of the South of the Far East.

The phenomenon of pathogen co-infection detected in a half-fed tick taken from a human in the south of the Far East was studied. Research was carried out on , , and cell lines, outbred mice, and chicken embryos using ELISA, PCR, IMFA, plaque formation, and electron microscopy. The tick contained an antigen and a genetic marker of the tick-borne encephalitis virus (TBEV).

Antiviral and Antioxidant Properties of Echinochrome A.

The aim of this study was to examine the in vitro antioxidant and antiviral activities of echinochrome A and echinochrome-based antioxidant composition against tick-borne encephalitis virus (TBEV) and herpes simplex virus type 1 (HSV-1). The antioxidant composition, which is a mixture of echinochrome A, ascorbic acid, and α-tocopherol (5:5:1), showed higher antioxidant and antiviral effects than echinochrome A. We suppose that echinochrome A and its composition can both directly affect virus particles and indirectly enhance antioxidant defense mechanisms in the hosting cell.

Immunogenicity and Protective Activity of a Chimeric Protein Based on the Domain III of the Tick-Borne Encephalitis Virus E Protein and the OmpF Porin of Incorporated into the TI-Complex.

Tick-borne encephalitis (TBE) is a widespread, dangerous infection. Unfortunately, all attempts to create safe anti-TBE subunit vaccines are still unsuccessful due to their low immunogenicity. The goal of the present work was to investigate the immunogenicity of a recombinant chimeric protein created by the fusion of the EIII protein, comprising domain III and a stem region of the tick-borne encephalitis virus (TBEV) E protein, and the OmpF porin of (OmpF-EIII).

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.

Molecular Mechanisms of Interaction Between Human Immune Cells and Far Eastern Tick-Borne Encephalitis Virus Strains.

Although studies have established that immune mechanisms are important in controlling tick-borne encephalitis virus (TBEV) infection, the interactions of different TBEV strains with cells of innate and adaptive immunity are not well understood. In this study, the ability of two Far Eastern subtype TBEV strains (Dal'negorsk and Primorye-183) with various degrees of pathogenicity for humans to modulate the expression of membrane molecules differently on human immune cells were investigated using a whole-blood flow cytometry-based assay. The whole-blood samples (from 10 healthy donors) were infected with TBEV strains and analyzed for the virus binding to the blood cells, as well as expression of adhesion (CD11b and ICAM-1) and activation (CD69, CD25, CD95) molecules on the surfaces of monocytes, granulocytes, natural killer (NK) cells, and T-lymphocytes (CD4+, CD8+) at selected times (3, 6, and 24 h post-infection).

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.

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.

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.

NS2B/NS3 protease: allosteric effect of mutations associated with the pathogenicity of tick-borne encephalitis virus.

The sequences of the protease domain of the tick-borne encephalitis (TBE) virus NS3 protein have two amino acid substitutions, 16 R→K and 45 S→F, in the highly pathogenic and poorly pathogenic strains of the virus, respectively. Two models of the NS2B-NS3 protease complex for the highly pathogenic and poorly pathogenic strains of the virus were constructed by homology modeling using the crystal structure of West Nile virus NS2B-NS3 protease as a template; 20 ns molecular dynamic simulations were performed for both models, the trajectories of the dynamic simulations were compared, and the averaged distance between the two models was calculated for each residue. Conformational differences between two models were revealed in the identified pocket.

Seroprevalence of West Nile virus in wild birds in far eastern Russia using a focus reduction neutralization test.

West Nile (WN) virus has been spreading geographically to non-endemic areas in various parts of the world. However, little is known about the extent of WN virus infection in Russia. Japanese encephalitis (JE) virus, which is closely related to WN virus, is prevalent throughout East Asia.

Characterization of neutralizing antibodies to Far Eastern of tick-borne encephalitis virus subtype and the antibody avidity for four tick-borne encephalitis vaccines in human.

We assessed the humoral immunity of 290 vaccinated persons against tick-borne encephalitis (TBE). During the first year and 2 years after the primary three vaccinations the antibodies to the Far Eastern subtype tick-borne encephalitis virus strain P-73 were detected by neutralization test after immunization with FSME-Immune Inject vaccine (Baxter Vaccine AG, Austria) in 88.2% and 78.

Characterization of Powassan viruses from Far Eastern Russia.

We report the isolation and detailed characterization of the novel strain, Partizansk/2006, of Powassan virus (POWV) from a human case of infection, which occurred in Primorsky krai, Russia, in 2006. Comparative complete genome sequence analysis of the Far Eastern strains Spassk-9 (1975), Nadezdinsk-1991 and Partizansk/2006 of POWV revealed that these strains are 99.8% similar to the LB strain, which was isolated in Canada in 1958.

Novel variant of tickborne encephalitis virus, Russia.

We isolated a novel strain of tickborne encephalitis virus (TBEV), Glubinnoe/2004, from a patient with a fatal case in Russia. We sequenced the strain, whose landmark features included 57 amino acid substitutions and 5 modified cleavage sites. Phylogenetically, Glubinnoe/2004 is a novel variant that belongs to the Eastern type of TBEV.

Evaluation of vaccine Encepur Adult for induction of human neutralizing antibodies against recent Far Eastern subtype strains of tick-borne encephalitis virus.

We studied humoral immune response of 44 volunteers from Primorsky krai (Russia) immunized with the vaccine Encepur Adult. Induction of the humoral response towards the recently isolated tick-borne encephalitis virus (TBEV) strains P-69, P-202, and P-73 was evaluated by neutralization test and enzyme immunoassay. These strains belong to Far Eastern TBEV subtype based on their genotype and antigenic structure but maintain significant genetic and antigenic variability.

Epizootiologic survey for Babesia microti among small wild mammals in northeastern Eurasia and a geographic diversity in the beta-tubulin gene sequences.

We previously reported that small wild rodents in Japan harbor two types of novel Babesia microti-like parasites (designated as Hobetsu and Kobe types), but not the type commonly found in the northeastern United States (U.S. type) where human babesiosis is endemic.

Distribution and characterization of tick-borne encephalitis viruses from Siberia and far-eastern Asia.

In this study, tick-borne encephalitis (TBE) viruses from Siberia and far-eastern Asia were characterized in order to determine virus subtype distribution. TBE viruses were isolated from ticks (Ixodes persulcatus) collected in the far-eastern (Khabarovsk and Vladivostok) and Siberian (Irkutsk) regions of Russia in 1999. Phylogenetic analysis showed that isolates formed distinct clusters of far-eastern and Siberian subtypes.