Long-term circulation of vaccine-derived poliovirus that causes paralytic disease

Successful implementation of the global poliomyelitis eradication program raises the problem of vaccination against poliomyelitis in the posteradication era. One of the options under consideration envisions completely stopping worldwide the use of the Sabin vaccine. This strategy is based on the assumption that the natural circulation of attenuated strains and their derivatives is strictly limited. Here, we report the characterization of a highly evolved derivative of the Sabin vaccine strain isolated in a case of paralytic poliomyelitis from a 7-month-old immunocompetent baby in an apparently adequately immunized population. Analysis of the genome of this isolate showed that it is a double (type 1-type 2-type 1) vaccine-derived recombinant. The number of mutations accumulated in both the type 1-derived and type 2-derived portions of the recombinant genome suggests that both had diverged from their vaccine predecessors approximately 2 years before the onset of the illness. This fact, along with other recent observations, points to the possibility of long-term circulation of Sabin vaccine strain derivatives associated with an increase in their neurovirulence. Comparison of genomic sequences of this and other evolved vaccine-derived isolates reveals some general features of natural poliovirus evolution. They include a very high preponderance and nonrandom distribution of synonymous substitutions, conservation of secondary structures of important cis-acting elements of the genome, and an apparently adaptive character of most of the amino acid mutations, with only a few of them occurring in the antigenic determinants. Another interesting feature is a frequent occurrence of tripartite intertypic recombinants with either type 1 or type 3 homotypic genomic ends.     

Production and characterization of monoclonal immunoglobulin A antibodies directed against Salmonella H:g,m flagellar antigen

Hybridomas were generated after intragastral immunization of BALB/c mice with live Salmonella suberu and subsequent fusion between isolated spleen lymphoblasts and myeloma cells. Three monoclonal antibodies (MAbs) of immunoglobulin A (IgA) isotype were selected and characterized. All of them were found to recognize the H:g epitope in enzyme-linked immunosorbent assay and immunoblotting but did not react with all H:g-expressing strains in slide agglutination test. All MAbs strongly agglutinated Salmonella enteritidis type strain and a large number of S. enteritidis clinical isolates. They were not bactericidal in the presence of complement. All hybridoma clones produced secretory IgA forms, which were found in the gastrointestinal tract of mice bearing hybridoma as a subcutaneous 'backpack' tumor or after intravenous application of purified MAbs. The IgA MAbs stability demonstrated in different tests together with their antigen specificity and strong agglutination ability make them a useful diagnostic tool for serotyping of Salmonella strains.     

Two new sulfated furostanol saponins from Tribulus terrestris

The known furostanol saponins methylprotodioscin and protodioscin and two new sulfated saponins, sodium salt of 26-O-beta-glucopyranosyl-22alpha-methoxy-(25R)-furost-5-ene-3beta,26-diol-3-O-alpha-rhamnopyranosyl-(1-->2)-beta-4-O-sulfo-glucopyranoside (methylprototribestin) and sodium salt of 26-O-beta-glucopyranosyl-22alpha-hydroxy-(25R)-furost-5-ene-3beta,26-diol-3-O-alpha-rhamnopyranosyl-(1-->2)-beta-4-O-sulfo-glucopyranoside (prototribestin) have been isolated from the aerial parts of Tribulus terrestris L. growing in Bulgaria. The structures of the new compounds were elucidated on the basis of 1D and 2D (DQF-COSY, TOCSY, HSQC-TOCSY, HSQC, HMBC, ROESY) NMR data, ESI mass spectra and chemical transformation.     

Abnormal protein patterns in blood serum and cerebrospinal fluid detected by capillary electrophoresis

Capillary zone electrophoresis and high-resolution agarose gel electrophoresis were compared to detect protein components in serum and cerebrospinal fluid of patients. Both electrophoretic methods proved to be useful for detection of protein abnormalities (e.g., mono- and oligoclonal bands) in biological fluids, but capillary electrophoresis offered several important advantages, such as sample application without preliminary concentration, lack of staining procedures, and on-line evaluation of patterns. Furthermore, capillary electrophoresis exhibits shorter analysis time and high resolution with low baseline noise. The results were proven to be powerful in diagnosis and monitoring of dyscrasias in routine laboratory practice.     

Age and sex characteristics of phospholipid composition of Wistar rat erythrocytes during postnatal ontogenesis

The composition of phospholipids and fatty acids of erythrocyte lipids of intact mature Wistar rats and their progeny in the age of 10, 15, 20, 30, 40, 60, 90 and 110 days was studied with the methods of micro-thin-layer and gas-liquid chromatography. Sex features and age mechanism of erythrocyte lipids composition forming in physiologically standard conditions were established. The fact that the composition of erythrocyte lipids of the untreated grown-up male rats in comparison with the female species is characterised with a lower concentration of phosphatidylinositol, a higher level of phosphatidylcholine and sphingomyelin, a higher saturation level of molecular types of phospholipids, was described. Three age periods of homeostasis of the erythrocyte lipids of the intact rats were distinguished. The postembryonic period (30-40 days after birth) is characterised with forming of the basic pool of erythrocyte lipids: getting to the stability in levels of the basic components of phospholipids and their fatty acids, coming out of phosphatidylinositol by the 40th day after birth. The period of sex-growing (60 days) is accompanied by spasmodic changes in the levels of fatty acids which is most common for female species: rapid increase in saturated and omega 3 polyunsaturated fatty acids, decrease in monoene and omega 6 polyene fatty acids. The period of maturity (110 days) is characterised by a slow metabolism of structural lipids and a stabilisation of their composition.     

Effect of dehydration and dDAVP on water permeability of basolateral membranes of epithelial cells in the kidney collecting tubules

Water permeability of the outer medullary collecting duct's (OMCD) basolateral membrane was determined in vitro in the tubules isolated from hyperhydrated or dehydrated Wistar rats. Oil was injected into the lumen to block apical membrane water permeability. OMCD fragments underwent a hypoosmic shock (600/300 mOsm) and epithelial cells volume increased ad recorded with a digital camera. The latter's rate was used to calculate apparent water permeability of the membrane (Pf). Treatment of the tubules with Hg2Cl2 suppressed the water permeability. Water deprivation and dDAVP induced an increase in the basolateral water permeability. The data obtained suggest that the water permeability of the OMCD basolateral membrane may be stimulated by vasopressin and water deprivation.     

Age-related changes of lipid spectrum, level of lipid peroxidation, and antioxidant defence in the liver and blood of rats

It has been shown that the lowest level of total lipids, cholesterol, triacylglycerols and products of lipid peroxidation of blood and liver, as a rule, is specific to adult rats. These characteristics are significantly higher for old and young animals. At the same time, the level of glutathione and alphatocopherols in adults' liver is much higher than in young and old rats. It suggests the lower level of processes of lipid peroxidation in adult mature rats. The relative high level of products of lipid peroxidation and low content of alpha-tocopherols in old rats' liver (against the background of higher activity and glutamineperoxidase, and glutathionereductase than in adults) suggests tocopherol deficiency in old animals. High content of total lipids, cholesterol and cholesterol entering into the composition of lipoprotein of different density, triacylglycerols, diene conjugates and malonic dialdehide, activity of glutathione-dependent enzymes of antioxidant defence in young animals as compared with these levels in adult rats seems to be associated with agerelated hypercholesterolemia and intensive plastic changes of a growing organism.     

Serial in vivo imaging of the targeted migration of human HSV-TK-transduced antigen-specific lymphocytes

New technologies are needed to characterize the migration, survival, and function of antigen-specific T cells in vivo. Here, we demonstrate that Epstein-Barr virus (EBV)--specific T cells transduced with vectors encoding herpes simplex virus-1 thymidine kinase (HSV-TK) selectively accumulate radiolabeled 2'-fluoro-2'-deoxy-1-beta-D-arabinofuranosyl-5-iodouracil (FIAU). After adoptive transfer, HSV-TK+ T cells labeled in vitro or in vivo with [131I]FIAU or [124I]FIAU can be noninvasively tracked in SCID mice bearing human tumor xenografts by serial images obtained by scintigraphy or positron emission tomography (PET), respectively. These T cells selectively accumulate in EBV+ tumors expressing the T cells' restricting HLA allele but not in EBV- or HLA-mismatched tumors. The concentrations of transduced T cells detected in tumors and tissues are closely correlated with the concentrations of label retained at each site. Radiolabeled transduced T cells retain their capacity to eliminate targeted tumors selectively. This technique for imaging the migration of ex vivo-transduced antigen-specific T cells in vivo is informative, nontoxic, and potentially applicable to humans.     

Lipophylic compounds from Euphorbia peplis L.--a halophytic plant from the Bulgarian Black Sea coast

The chemical composition of the lipophylic fraction from the halophytic plant Euphorbia peplis L. was investigated. Compared to other terrestrial higher plants an increase of triacylglycerols and especially of glycolipids was observed. The main phospholipid was phosphatidyl choline, followed by almost equal concentrations of phosphatidyl ethanolamine and phosphatidyl glycerol. A relatively high concentration of phosphatidic acids (6.5% of the total phospholipids) was found. The main sterol appeared to be sitosterol and significant amounts of tetracyclic triterpene alcohols were found. The composition of the volatile compounds is relatively simple and only one chlorinated compound, identified as 2,2-diethoxy-1-chloroethane, was found. There was a strong toxicity of the total lipophylic extract towards Artemia salina.     

Antiinfluenza virus effect of extracts from marine algae and invertebrates

Sixty products, derived from marine organisms, typical of the Bulgarian Black Sea coast, were examined for inhibitory activity on the reproduction of influenza viruses in tissue cultures. The antiviral effect was investigated by the reduction of virus infectivity. Using representative strains of influenza virus it was shown that apparently the inhibitory effect was strain-specific. The most effective products were further studied in fertile hen's eggs and in experimental influenza infection in white mice.