[Tick-borne encephalitis with fulminant course and lethal outcome in patients after plural vaccination].

In the Kurgan region, the Siberian subtype of the tick-borne encephalitis virus (TBEV) is dominant. The vaccines prepared from Far-Eastern TBEV subtype are used in this area. Among TBE patients in 2007-2011, 23.79% were vaccinated according to complete or incomplete course. 76.9% of persons were vaccinated with Encevir vaccine, Tomsk. An unusual focal form of TBE with fulminant disease with lethal outcome was developed in a patient who was vaccinated 6 times with heterotype vaccines produced using the strains of the Far-Eastern TBE subtype. Inoculation of immunoglobulin in hospital produced aggravation of clinical symptoms, development of convulsions, brain oedema, and respiratory distress syndrome. The disease continues only 55 hours from first symptoms to fatal outcome. Siberian subtype of TBEV was isolated from patient spinal cord (Kurgan-118-2010 strain). Possible mechanisms of this disease are discussed.

[Polytypic strains in the genofund of tick-borne encephalitis virus].

Eighteen polytypic tick-borne encephalitis virus (TBEV) strains containing the fragments of E and NS1 protein genes of Siberian and Far Eastern, occasionally Siberian and European subtypes were isolated in the European and Asian parts of the tick-borne encephalitis (TBE) area. They were identified using real-time polymerase chain reaction, hybridization-fluorescence detection with genotype-specific probes, restriction fragment length polymorphism analysis, and E protein sequencing. The polytypic strains were isolated from individual Ixodes persulcatus ticks, their pools, from the blood of patients and the brain of dead patients. The isolation rates of the polytypic strains in the sympathry area of different TBEV subtypes ranged from 4.4% (the Irkutsk Region) to 15.1% (the Yaroslavl Region). In addition to 2 polytypic strains, a strain similar to the TBEV 886-84 strain was isolated. The TBEV subtypes entering into the composition of the polytypic strains show nongenetic interactions, such as neutral replication or competition. The polytypic strains are stable during passages in the cultured pig embryo kidney epithelial cells and on cloning. Mouse brain passage promotes dissociation of polytypic strains. The conditions for the formation of polytypic strains and their role in the etiology of TBE are discussed.

[Interaction of the Siberian and Far Eastern subtypes of tick-borne encephalitis virus in mammals with mixed infection. Competition of the subtypes in acute and inapparent infection].

Long-term monitoring of natural tick-borne encephalitis virus (TBEV) populations could reveal the change of TBEV subtypes, the displacement of the Far Eastern (FE) subtype, and its substitution for the Siberian (Sib) subtype. Acute and inapparent mixed infections were studied in Syrian hamsters to understand this phenomenon. The animals were inoculated with the Sib subtype and then with the FE one of TBEV (JQ845440-YaroslavI-Aver-08 and Fj214132-Kemerovo-Phateev-1954 strains). The inapparent form developed more frequently in mixed infection. Viral progeny was genotyped by reverse transcription polymerase chain reaction and hybridization fluorescence detection using genotype-specific probes. Independent reproduction of strains in the brain gave way to competition. The FE subtype dominated in hamster youngsters with acute infection. The Sib subtype had selective benefits in asymptomatic infection (adult hamsters infected intracerebrally and subcutaneously and youngsters infected subcutaneously). The competition of the subtypes was imperfect.

[Interaction of the Siberian and Far Eastern subtypes of tick-borne encephalitis virus in mammals with mixed infection. I. Factors influencing the type of interaction].

Polytypic strains containing the fragments of genes of Siberian and Far Eastern tick-borne encephalitis (TBE) virus subtypes were isolated from the brain of fatal TBE patients, the blood of TBE patients, and Ixodes persulcatus ticks in the foci of concomitant circulation of the two subtypes. The interaction of the Siberian and Far Eastern TBE virus subtypes was studied in the neural phase of the infection of albino mice and Syrian hamsters in order to understand conditions for formation of these strains and their role in the etiology of acute TBE. Their viral progeny was genotyped by reverse transcription-polymerase chain reaction and fluorescence hybridization assay with genotype-specific probes. Mixed infection showed an effect of synergism, independent reproduction of the two subtypes in the brain and spleen, competitive exclusion of one subtype from the viral population. The type of the Interaction depended on the species of animals, the properties of partner strains, and the target organ.

[Evolution of tick-borne encephalitis and a problem of evolution of its causative agent].

The evolution of tick-borne encephalitis (TBE) is marked by the expanded nosological area, the transformation of landscapes, the formation of anthropurgic foci, the change of environmental systems, the increase of mortality rate mainly among urban dwellers, as well as pathomorphism. The evolution of natural TBE virus (TBEV) populations was studied in Eastern and Western Siberia, Middle Urals, and the European part of the nosological area. The paper first describes the types of evolutionary transformations of viral populations under the conditions of a varying environmental and epidemiological situation. These include: 1) the change of TBEV subtypes over 50-60 years; substitution of the Far-Eastern subtype for its Siberian subtype (the Sverdlovsk and Kemerovo regions); 2) the steady-state circulation of one Siberian subtype with mutanttypes being accumulated (the Vologda region); 3) co-existence of the Far-Eastern and Siberian subtypes with the common vector Ixodes persulcatus (the Yaroslavl and Irkutsk regions, etc.); 4) original mixed TBEV strains including the gene sites of proteins E and NSI of two subtypes. There is new evidence that the Siberian subtype is able to induce focal TBE forms, leading to death.

[Comparative analysis of virulence of the Siberian and Far-East subtypes of the tick-born encephalitis virus]. / Sravnitel'nyi analiz virulentnosti sibirskogo i dal'nevostochnogo podtipov virusa kleshchevogo entsefalita.

The Siberian subtype of the tick-borne encephalitis virus (TEV) is different from the Far-East subtype by a moderate virulence observed in Siberian hamsters and by a low infection development rate (100 strains were compared). No differences were found in neuro-invasiveness. Clinical findings and experiments with monkeys denote the ability of the Siberian subtype to provoke severe forms of tick-borne encephalitis (TBE). The inflammation-and-degenerative changes were localized in the brain cortex, subcortical ganglions, nuclei of medulla oblongata, in the cortex and nuclei of the cerebellum as well as in the anterior horns of the spinal cord. 18 disease cases triggered by the Siberian TEV subtypes in residents of the Western and Eastern Siberia and of Central Russia (Yaroslavl Region), including 7 acute TBE cases (5 lethal outcomes), as well as 11 chronic TBE cases are analyzed. The viral RNA was found in the cortex, medulla oblongata, horn and in the cervical part of the spinal cord of those diseased of acute TBE. Sequences of genotyped strains were presented to Gen Bank, NCBI (AY363846-AY363865).

[The Siberian and Far-Eastern subtypes of tick-borne encephalitis virus registered in Russia's Asian regions: genetic and antigen characteristics of the strains]. / Sibirskii i dal'nevostochnyi podtipy virusa kleshevogo éntsefalita v evropeiskikh i aziatskikh regionakh Rossii: geneticheskaia i antigennaia kharakteristika shtammov.

Agar gel precipitation test with cross-adsorbed immune sera was used for the antigenic differentiation of strains of tick-borne encephalitis virus (TBEV). Fifty strains of the Far East TBEV serotype and 46 strains of the Siberian (Aina) TBEV serotype were isolated from Ixodes persulcatus, which is the main vector of the above TBEV subtypes in the Asian and European parts of Russia. The fragment of the envelope protein gene was sequenced for TBEV strains. Sequences of new-group strains of the Siberian subtypes isolated from 3 patients with chronic TBE and from brain tissues of 4 deceased patients were determined. Lethal TBE outcomes were registered in Siberia (Irkutsk Region and Krasnoyarsk Territory) and in Russia's European part (Yaroslavl Region).

[The effect of pregna-D'-pentarans on myometrial contractile activity in pregnant rats]. / Vliianie pregna-D'-pentaranov na sokratitel'nuiu aktivnost' miometriia beremennykh krys.

The authors studied the effect of synthetic gestagens on spontaneous contractility of the myometrium in pregnant rats. The direction of the effect of progesterone and its analogs on the contractility is determined by stereochemistry of the linkage of rings A and B of the steroid molecule. Compounds possessing translinkage (5 beta-steroids) increase the amplitude of myometrium contraction, whereas their analogs with cms-coupling of rings A and B (5 alpha-steroids), and 4,5-unsaturated steroids reduce it.

[A comparative analysis of proteins from persistent and antigen-defective strains of tick-borne encephalitis virus]. / Sravnitel'nyi analiz belkov persistiruiushchikh i antigenno-defektnykhshtammov virusa kleshchevogo éntsefalita.

Structural (E) and three nonstructural (NS1, NS3, and NS5) proteins of persistent and antigen-defective strains of tick-borne encephalitis virus are compared by immunoblotting with monoclonal antibodies to the corresponding proteins of strain Sofyin. Appreciable phenotypical differences were revealed between antigen-defective strains, but no immunological modifications as concerns the studied antigenic structures. The size of the reference NS3 protein differed from that of the persistent virus strains. Similar proteins detected in the antigenic preparations of strain Zausaev may have notable modifications.

[Japanese encephalitis in citizens of Russia who travel abroad]. / Iaponskii éntsefalit u grazhdan Rossii, vyezzhaiushchikh za rubezh.

Typical and atypical forms of Japanese encephalitis (JE) in the Russians visiting Asian countries endemic for JE are described. A patient who contracted the disease in China developed 5 months after returning to Russia acute meningoencephalitis with mental disorders and a lethal outcome on day 5 with bulbar symptoms. JE virus (strain SP-69) was isolated from his brain. By antigenic and genetic properties this strain occupies an intermediate position between Jagar-01 and Nakayama serotypes. A pregnant woman (6 months gestation) who lived in Birma for 3 years suffered from encephalitis running a protracted (more than 6 months) course; mildly manifest pyramidal signs were detected in her one-year-old infant with a normal mental status. Serologic studies showed that the disease was caused by infection with Jagar-01 serotype of JE virus. A patient contracting the disease 1 month after arrival in Japan developed a recurrent pattern of the illness: the diagnosis of JE was confirmed by repeated detection of virus-neutralizing anti-bodies in the blood and liquor. None of the patients was vaccinated against JE. Indications to prophylactic vaccination of subjects leaving for countries endemic for JE are discussed.

[Vergina-like strains of tick-borne encephalitis in Russia]. / Verginapodobnye shtammy virusa kleshchevogo éntsefalita v Rossii.

The Greek strain Vergina representing an individual third serotype of tick-borne encephalitis (TBE) virus has been compared with 13 TBE strains isolated on the territory of Russia and Central Asia (in Kirghizia). A kit of deoxyoligonucleotide probes complementary to genome sites of Neudorfle strain of the TBE Central European subtype (protein C and prM genes) and of strain Sofyin of the Eastern subtype (protein E, C, M, prM, ns 1, ns 2b, ns 4b genes) was used in molecular hybridization of nucleic acids. Vergina strain was referred to the genetic variant VI prevalent in the western part of the East European plain, in Udmurtia, in the Altai mountains, and in West Siberia. By its antigenic properties Vergina strain is most close to strain Yar-90 isolated in the Yaroslavl district from Ixodes persulcatus ticks.

[The genetic characteristics of the Vergina serotype of the tick-borne encephalitis virus and its pathogenetic traits]. / Genetichskaia kharakteristika serotipa Vergina virusa kleshchevogo éntsefalita i osobennosti ego patogennosti.

The Greek Vergina strain of tick-borne encephalitis (TBE) virus was studied in comparison with 7 other strains by molecular hybridization of nucleic acids and by clinicomorphological markers of pathogenicity for monkeys and Syrian hamsters. By the genetical features the Vergina strain differed from the eastern and western TBE subtypes but was found to be similar to the strains of other subtypes of the Urals-Siberian, east-Siberian (Aina-1448) and Central Asian antigenic variant. This group of strains hybridized with cDNA at 65 degrees C only in the absence of 50% formamide, reacted with probe 1115 complementary to protein E gene, with 1-3 probes complementary to the conservative region of the genome but did not react with the probes corresponding to the variable regions of the genome. The Vergina strain is close to TBE genotype III. The Vergina strain was found to be virulent inducing subacute meningoencephalomyelitis which developed slowly and was accompanied by less marked morphological lesions in the cerebral cortex than those induced by the eastern subtype. The Vergina strain was demonstrated to persist in the brain, liver, spleen, and lymph node tissues.

[The phenomenon of antigenic defectiveness in naturally circulating strains of the tick-borne encephalitis virus and its possible connection to seronegative forms of the disease]. / Iavlenie antigennoi defektnosti u tsirkuliruiushchikh v prirode shtammov virusa kleshchevogo éntsefalita i ego vozmozhnaia sviaz' s seronegativnymi formami zabolevaniia.

Ten strains of tick-borne encephalitis (TBE) virus isolated from single specimens of I. persulcatus ticks were studied. The strains were divided into antigenically complete (AC) and antigenically defective (AD), depending on the presence or absence of some virus antigens in concentrated virus preparations, characteristics in rocket immune electrophoresis (RIEP), rate and intensity of humoral immune response in monkeys and rabbits, and plaque size in SPEV cell culture. The AC-strain markers include high activities of precipitating, hemagglutinating (HA), and complement-fixing (CF) antigens, formation of precipitates moving in rocket shape towards anode and cathode in RIEP, rapid development of antihemagglutinins and virus-neutralizing antibodies, large plaques (3-5 mm). The AD variants are characterized by the lack of HA and precipitating activity, low titres of CF antigen, slow and poor immune response, the lack of cathode precipitate "rocket", very small plaques. The antigenic defectiveness is transitory and shows in early passages; after 10-11 passages in SPEV cell cultures or in white mice, transformation AD----AC occurs. A transformed strain is neutralized, like standard TBE strains, by blood sera of a typical patient with poliomyelitis-like form of TBE. Examinations of blood sera from the population of an endemic zone (Yaroslavl Province) and 67 TBE patients (Kurgan Province) demonstrated the association of AC and AD variants with the formation of immune portion of the population and TBE etiology. Cases of the disease confirmed by seroconversion in HI with commercial diagnosticum are associated with AC variants, whereas AD variants are associated with those TBE cases which are difficult to diagnose using the commercial diagnosticum.

[The effect of preparations of specific and nonspecific transfer-factor on the course of experimental tick-borne encephalitis]. / Vliianie preparatov spetsificheskogo i nespetsificheskogo transfer-faktora na techenie éksperimental'nogo kleshchevogo éntsefalita.

Syrian hamsters subcutaneously inoculated with tick-borne encephalitis (TBE) virus were given transfer-factor (TF) preparations derived by different methods. The preparation of specific TF was obtained from the blood leukocytes of TBE convalescents. The nonspecific TF preparations were made of the lymphocytes of the tonsils removed from children with chronic tonsillitis outside the TBE focus. The effect of the TF preparations depended on the TBE virus strain and dose, TF preparation dosage schedule and characteristics. The specific TF preparations stimulated the development of acute fatal TBE after 3 injections at intervals of 0, 48 and 96 hours postinoculation with the virus. The preparations of nonspecific TF potentiate the infection after preliminary (24 hours) and simultaneous inoculation of the virus, producing transformation of asymptomatic infection to subacute TBE or exacerbation of the subacute process. A significant inhibition of TBE virus reproduction in spleen and brain tissues is observed after inoculation of a nonspecific TF F150 preparation 72 hours after virus inoculation, that is at the time when the virus has been already localized in the central nervous system. The results of the study indicate that the protective effect of TF is mainly associated with nonspecific immunopharmacological activity of the preparations.

[The effect of myelopeptides on the persistence of tick-borne encephalitis virus in monkeys]. / Vliianie mielopeptidov na persistentsiiu virusa kleshchevogo éntsefalita v organizme obez'ian.

Myelopeptides (MP), bioregulatory molecules of bone marrow origin, exert a protective effect in persistence of tick-borne encephalitis virus in cynomolgus monkeys (Macaca fascicularis). The experiments involved 32 monkeys. The effect of MP was observed after one or two subcutaneous injections in a dose of 1 mg within 1.5-2 months after virus infection. The effect consists in 25-fold reduction of the frequency of virus persistence, marked limitation of the zone of spread of the persisting virus, including the central nervous system (CNS), decrease in virulence of the persisting virus, and lack of morphological signs of progress of the pathological process in the CNS. The protective effect was also observed when the infected monkeys were treated with MP and inactivated concentrated TBE vaccine. At the same time, the vaccine alone exerted a much less marked effect on the persisting TBE virus producing only a 2-fold reduction in the frequency of persistence without limitation of the zones of virus spread. In acute TBE in BALB/c mice, the effect of MP is observed irregularly. The marked protective effect of MP in TBE virus persistence in monkeys is not associated with stimulation of humoral immunity but is mediated by other immunological mechanisms requiring further study.

Persistence of tick-borne encephalitis virus in monkeys. VII. Some features of the immune response.

Tick-borne encephalitis (TBE) virus persists in experimentally infected rhesus monkeys in the presence of humoral antibodies. Various dynamics of the humoral response (stable, increasing, decreasing, undulatory titres) have been noted, associated with complete or incomplete set of antibodies. Always present were the virus-neutralizing antibodies, often the complement-fixing antibodies, less frequently precipitating and haemagglutination inhibition (HI) antibodies were found. There was a correlation between the set of antibodies present and the virus-specific antigens expressed; the persisting TBE virus was usually deficient in haemagglutinin synthesis. In cases of asymptomatic infection a more expressed and long-lasting immunity as observed with the persistence of TBE virus in organs of the immune system.

Persistence of tick-borne encephalitis virus IV. Virus localization after intracerebral inoculation.

Tick-borne encephalitis (TBE) virus was isolated from the brains and spinal cords, blood, livers, lymph nodes and kidneys from Macaca rhesus monkeys showing acute and subacute fatal encephalitis. In subacute encephalitis, virus titres in the CNS were lower than in acute disease (3.0--6.2 against 3.8--8.3 log LD50/ml). TBE virus localization in chronic encephalitis was largely the same as in acute and subacute disease. In monkeys with a chronic course and stable paralysis of the upper extremity, infectious TBE virus was isolated on day 383 from subcortical ganglia and spinal cord. In lymph nodes and spleen, it could be detected only by a combination of methods (co-cultivation in association with fluorescent antibody technique and complement-fixation test, explantation of organ fragments) more sensitive than is the inoculation of mice with organ homogenates. TBE virus was detected by the same methods on day 90 in the CNS and internal organs of a monkey with chronic encephalitis in the stage of remission.

Persistence of tick-borne encephalitis virus in monkeys. V. Virus localization after subcutaneous inoculation.

In 28 Macaca rhesus monkeys inoculated subcutaneously (s.c.) with different strains and mutants of tick-borne encephalitis (TBE) virus and developing asymptomatic infection, TBE virus and the virus-specific antigen were found at different intervals up to 302 days post inoculation (p.i.) in the CNS and internal organs (liver, spleen, lymph nodes, kidneys). When cyclophosphane (CP) was used as an immunosuppressor, no significant changes in virus distribution were observed with the exception of more frequent isolations at early intervals from kidneys and at late intervals from spleen. With or without CP administration virus was found in the spinal cord at 3--6 days, in the cerebellum and subcortical ganglia at 11--14 days, in the cerebral cortex at 19 days p.i. Early after inoculation the virus was more frequently isolated from the CNS than from the internal organs; later (93--302 days p.i.) the persisting virus or virus-specific antigen were predominantly found in internal organs. The set of sensitive methods used facilitated to detect the persistence of TBE virus in noninfectious form in monkeys with asymptomatic infection.