The laboratory diagnosis of spring-summer infections in Yekaterinburg in the epidemic season for tick-borne encephalitis

The authors propose a comprehensive approach to laboratory diagnosis of seasonal transmissible infections, based on modern methods permitting etiological deciphering of disease. A universal diagnostic algorithm notably accelerated the laboratory diagnosis due to cutting the period between collection of material from a patient and consecutive screening for antibodies to agents of tick-borne encephalitis, Lyme disease, and California encephalitis.     

Proteolytic activation of tick-borne encephalitis virus by furin

Flaviviruses are assembled intracellularly in an immature form containing heterodimers of two envelope proteins, E and prM. Shortly before the virion exits the cell, prM is cleaved by a cellular enzyme, and this processing step can be blocked by treatment with agents that raise the pH of exocytic compartments. We carried out in vivo and in vitro studies with tick-borne encephalitis (TBE) virus to investigate the possible role of furin in this process as well as the functional consequences of prM cleavage. We found that prM in immature virions can be correctly cleaved in vitro by recombinant bovine furin but that efficient cleavage occurs only after exposure of the virion to mildly acidic pH. The data suggest that exposure to an acidic environment induces an irreversible structural change that renders the cleavage site accessible to the enzyme. Cleavage by furin in vitro resulted in biological activation, as shown by a 100-fold increase in specific infectivity, the acquisition of membrane fusion and hemagglutination activity, and the ability of the envelope proteins to undergo low-pH-induced structural rearrangements characteristic of mature virions. In vivo, prM cleavage was blocked by a furin inhibitor, and infection of the furin-deficient cell line LoVo yielded only immature virions, suggesting that furin is essential for cleavage activation of flaviviruses.     

Development of Kozhevnikov''s epilepsy in tick-borne encephalitis

The examination was carried out in 787 patients with macrofocal myocardial infarction. The most frequently encountered variant of intraventricular block in males was the right bundle branch block, in females--the left bundle branch block. The rarest variant of intraventricular conductivity disorders in myocardial infarction was the left-posterior hemiblock. The prognostically severest variant of bilateral block consists in a combination of the right bundle branch block with the left-posterior hemiblock. The leading causes of death among the patients with myocardial infarction and intraventricular blocks were acute (cardiogenic shock, pulmonary oedema) and chronic cardiac insufficiency. In patients with bilateral blocks the frequent causes of death were, along with cardiac insufficiency, also arrhythmias (ventricular fibrillation, asystole).     

The prevention of tick-borne encephalitis (author's transl)

Tick-borne encephalitis is one of the most frequently-encountered virus diseases of the central nervous system in Europe. Hence, prophylactic measures for the prevention of tick-borne encephalitis are of particular importance, especially since it is virtually impossible to influence the course of the manifest disease by means of current therapeutic procedures. Moreover, complications (paralysis and other sequelae) are frequent. A recently-developed vaccine (killed virus) is capable of providing easy and long-lasting protection for a large part of the population. The safety and efficacy of the vaccine was proved in 30,000 persons who were vaccinated in a field trial. Wide-scale implementation may be recommended mainly for persons under regular exposure, but also for the protection of people remaining in an endemic area for a short time only. However, if immediate protection of non-immunised persons is required, i.e. persons who discover ticks on their body or who show the presumptive signs of an existing virus infection, passive immunisation with tick-borne encephalitis immune globulin is recommended.     

Fatal encephalitis caused by concomitant infection with tick-borne encephalitis virus and Borrelia burgdorferi

We describe a 38-year-old farmer from the southwestern archipelago of Finland where both tick-borne encephalitis (TBE) virus and Borrelia burgdorferi are endemic. He presented with fever and headache, developed severe meningoencephalitis in 3 days, and, after 1 month, died without regaining consciousness. High titers of IgG and IgM antibodies to TBE virus were present in both serum and CSF. Serology for Borrelia was negative. Autopsy revealed necrotizing encephalitis and myelitis with involvement of the dorsal root ganglion. With use of polymerase chain reaction tests, segments of two separate genes of B. burgdorferi were amplified from the patient's CSF. This case demonstrates that the possibility of dual infection should be considered for patients residing in geographic areas where Ixodes ticks may carry both the TBE virus and B. burgdorferi. We believe that the most severe damage in this case was caused by TBE virus rather than by B. burgdorferi. Nevertheless, the coinfection might have contributed to the fatal outcome that has not been previously observed in Finnish patients with TBE.     

Typifying foci of tick-borne encephalitis in the pre-Baikal

The existence of tick-borne encephalitis foci of several landscape types was revealed in the Prebaikalye. Of particular interest were foci of the forest-steppe type, in which virus strains of the Western serological type circulated along with the Eastern serological type strain of the tick-borne encephalitis virus. It was shown that infection of man was possible not only by transmissive, but also by the almientary route--through cow milk.     

The morphological characteristics of cell death in different forms of acute tick-borne encephalitis

The study was aimed to identify different types of cell death in monkey brain in flavivirus experimental encephalitis. 10 brain areas most vulnerable ("indicator") of the disease in its different forms (symptomless, intermediate and severe) were examined in animals infected intracerebrally with viruses of tick-borne encephalitis. Cells of ectodermal and mesenchymal origin displayed apoptosis that was most pronounced in intermediate form of the severity of the disease. Apoptosis was not characteristic for the symptomless form of tick-borne encephalitis. Two types of apoptosis morphological manifestations in nerve cells were described.     

Importance of localized skin infection in tick-borne encephalitis virus transmission

Arboviruses are transmitted to vertebrates by the "bite" of infected arthropods. Events at the site of virus deposition are largely unknown despite increasing evidence that blood-sucking arthropods immunomodulate their skin site of feeding. This question is particularly relevant for ixodid ticks that feed for several days. To examine events under conditions mimicking tick-borne encephalitis (TBE) virus transmission in nature (i.e., infected and uninfected Ixodes ricinus ticks feeding on the same animal), infected adult and uninfected nymphal ticks were placed in one retaining chamber (skin site A) and uninfected nymphs were placed within a second chamber posteriorly (skin site B) on two natural host species, yellow-necked field mice (Apodemus flavicollis) and bank voles (Clethrionomys glareolus). Virus transmission from infected to uninfected cofeeding ticks was correlated with infection in the skin site of tick feeding. Furthermore, virus was recruited preferentially to the site in which ticks were feeding compared with uninfested skin sites. Viremia did not correspond with a generalized infection of the skin; virus was not detected in an uninfested skin site (C) of 12/13 natural hosts that had viremia levels > or = 2.0 log10 ic mouse LD50/0.02 ml blood. To characterize infected cells, laboratory mouse strains were infested with infected ticks and then explants were removed from selected skin sites and floated on culture medium. Numerous leukocytes were found to migrate from the skin explants of tick feeding sites. Two-color immunocytochemistry revealed viral antigen in both migratory Langerhans cells and neutrophils; in addition, the migratory monocyte/macrophages were shown to produce infectious virus. The results indicate that the local skin site of tick feeding is an important focus of viral replication early after TBE virus transmission by ticks. Cellular infiltration of tick feeding sites, and the migration of cells from such sites, may provide a vehicle for transmission between infected and uninfected cofeeding ticks that is independent of a patent viremia. The data support the hypothesis that viremia is a product, rather than a prerequisite, of tick-borne virus transmission.     

The distribution of tick-borne encephalitis virus-infected ticks along a linear census route

An individual study of Ixodes persulcatus Schulze, 1930, established that the distribution of infected ticks differs from the normal distribution and it is most close to the Poisson distribution. There is a tendency to deviation from the uniform-random distribution associated with higher infected tick contact rates in some parts of the route.     

Virologic diagnosis of an outbreak of epidemic hemorrhagic conjunctivitis by an indirect immunofluorescence technique. Cuba.1989

The causative agent of an hemorrhagic conjunctivitis outbreak was assessed through the study of 18 conjunctival exudates using the indirect immunofluorescence technique and isolation in cell culture of human embryo fibroblasts. In addition, 395 paired serum samples were studied and Enterovirus 70 was found to be responsible for the outbreak.     

Adjuvant/carrier activity of inactivated tick-borne encephalitis virus

This study was designed to measure the electroencephalogram (EEG) after exercise with increasing intensity. In a field test with increments in running velocity a 2-min EEG was recorded, together with blood lactate concentration and heart rate, after each stage. An individual protocol was used, with up to six stages of running to ensure comparability of exercise intensity among the subjects, in each of 19 athletes (17 men, 2 women) experienced in leisure-time running. The exercise consisted initially of three running stages of aerobic exercise intensity without blood lactate accumulation followed by stages with an increase of lactate concentration. The protocol of the field test led to a progressive increase in cortical activity directly after the stages without blood lactate accumulation mainly in the delta frequency band, followed by theta and alpha-1 frequency band, and less pronounced in the alpha-2 and in the beta frequency bands. After the stages with an onset and further increase of blood lactate accumulation significant decreases in the beta-2, beta-1 and alpha-1 frequency bands occurred predominantly in temporal (T3, T4, T5, and T6) and occipital (O1, and O2) electrode positions, indicating a stage-by-stage decrease of activity. This decrease may be explained by feed-back from working muscle, via afferents to the cortex from intero- and proprio-receptors and affective processes. This could suggest that through a higher running intensity indicated by an onset of blood lactate accumulation metabolic and mechanical changes led to alterations within the afferent systems influencing the level of cortical activity.     

Ultrastructural changes in the central nervous system of mice in tick-borne encephalitis

Tick-borne encephalitis virus is localized in nerve cells and intracellular spaces. According to the nature of ultrastructural changes, the pathological process in nerve cells may be divided into three stages connected with the stages of virus reproduction. In the first stage, the protein-synthesizing systems of the cell are degraded. In the second stage specific virus inclusions form in the cell cytoplasm as aggregates of mature and immature virions alongside with destruction of ultrastructures and growth of smooth membranes. In the third stage degradation of neurons is accompanied by necrobiosis and discomplexation of the surrounding glial elements, processes, cells of the inflammatory infiltrate and capillary walls. A certain combination of nonspecific changes in organelles of various cells with viral inclusions makes the ultrastructural picture of the focus of lesions in tick-borne encephalitis sufficiently characteristic for differential pathological diagnosis.     

The virus causing encephalomyelitis in sheep in Spain: a new member of the tick-borne encephalitis group

An analysis of endothelin in atherosclerotic plaques using immunohistochemical methods showed that endothelin not only existed in endothelial cells, large amounts were also found in the proliferating intimal vascular smooth muscle cells (VSMC). In the de-endothelized thoracic aorta of rats, significant amounts of endothelin could be produced by proliferating intimal VSMC. Radio-immunological studies demonstrated that the extent of VSMC proliferation was in direct ratio to endothelin content, which suggests that production of endothelin is related to proliferation of VSMC in atherosclerotic plaques.     

Some determinants of milk ingestion in suckling rats.

Eight experiments were conducted to examine several possible determinants and controls of milk intake in 10-day-old preweanling Sprague-Dawley rats. Results indicate that while the amount of milk the mother provides is a major determinant of milk consumption, pups will individually adjust their intake in response to certain treatments. Deprived pups ingested more milk than nondeprived littermate controls if given access to enough milk. Intragastric intubations of skimmed milk or distilled water reduced milk intake; heavy cream or isotonic saline did not. Injections of polyethylene glycol or formalin, which produced hypovolemia, increased milk consumption, and hypertonic saline decreased it. Results indicate that preweanling rats are behaviorally responsive to certain changes in body fluids and suggest that milk intake involves more than an invariant reflex. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Affinity labelling of the tick-borne encephalitis virus RNA replicase proteins by 4-N-exo-base-substituted photoreactive CTP analogs

4-N-exo-base-substituted photoreactive analogs of CTP were designed and synthesized. Two flavivirus proteins NS5 and NS3 are shown to be labelled after RNA synthesis in the presence of the analogs, irradiation by UV-light (313 nm) and subsequent [alpha-32P]NTP incorporation.     

Zoonoses transmitted by ticks in forest workers (tick-borne encephalitis and Lyme borreliosis): preliminary results

In order to investigate the diffusion of infections transmitted by ticks (TBE and Lyme borreliosis) in forest workers, a serological investigation was carried out in the Province of Trento (Northern Italy) on the sera of 465 subjects at potential risk (foresters, hunters, woodcutters, gamekeepers). Antibodies for TBE virus were found in 5 subjects (1.07%) working in the same area, and antibodies for Borrelia burgdorferi were found in 15 subjects (3%). All three clinical cases of TBE identified in the Province of Trento reported that they had been bitten by ticks in the same geographical area. The presence of specific antibodies for TBE virus was tested on the sera of animals grazing in several areas: 4 positive cases were observed in the same area as the human cases reported above.     

An interstate outbreak of tick-borne relapsing fever among vacationers at a Rocky Mountain cabin

Clinical observation suggests that deformities of the foot and ankle are common in children with cerebral palsy. Two hundred children with cerebral palsy attending the Central Remedial Clinic were examined and photographed. The children had no previous surgical intervention and were between 1.5 and 19 years of age. Deformities were assessed and related to the type of cerebral palsy and mobility status.