Genetic reassortants for identification of the genome segment coding for the bluetongue virus hemagglutinin.

Two bluetongue virus (BTV) serotypes isolated in Australia and two selected reassortants derived from cells coinfected with these viruses have been used to identify the gene coding for the virus hemagglutinin. The parent viruses had characteristic hemagglutination patterns: BTV type 20 agglutinated sheep erythrocytes only; and BTV type 21 agglutinated sheep, bovine, human, and goose erythrocytes. Analysis of the two virus clones that had reassorted in genes coding for the outer capsid polypeptides demonstrated that hemagglutination and hemagglutination inhibition are functions associated with the outer capsid protein (VP2), which is encoded by genome segment 2.     

Reduced adherence of micro-organisms to human mucosal epithelial cells following treatment with Taurolin, a novel antimicrobial agent

Taurolin, a non-antibiotic antimicrobial agent, significantly reduced the adherence of buccal and vaginal strains of Candida albicans blastospores and urine isolates of Escherichia coli and Staphylococcus saprophyticus to epithelial cells. Light microscopy and radio-isotopic counting methods were used to quantify the adherence of the micro-organisms to either uroepithelial or buccal epithelial cells. A maximum reduction in adherence of approximately 65% was obtained. The anti-adherence capacity was time-dependent, requiring a contact time of 30 min to achieve maximum effect. Taurolin at sub-minimum inhibitory concentrations (MIC) significantly reduced the adherence of Candida and E. coli. A concentration slightly higher than the MIC was required for Staph. saprophyticus. Treatment of either epithelial cells or micro-organisms with Taurolin resulted in reduced adherence of microorganisms.     

Inhibition of growth of HeLa and WI-38 cells by dehydroepiandrosterone and its reversal by ribo- and deoxyribonucleosides

Dehydroepiandrosterone (DHEA), an adrenal steroid of no known biological function, is a potent inhibitor of mammalian glucose-6-phosphate dehydrogenase (G6PDH). DHEA inhibited the growth of two stains of HeLa and WI-38 cells in culture. One of the HeLa strains, TCRC-2, was about 10x as sensitive to growth inhibition as the two other cell lines. The G6PDH activity in cell extracts of HeLa TCRC-2 was also much more sensitive to DHEA inhibition than the G6PDH activities of the other cell lines. The addition of a combination of four deoxyribonucleosides and four ribonucleosides to the culture medium overcame the DHEA-induced growth inhibition in the HeLa TCRC-2 line.     

Isolation of protozoa from water associated with a legionellosis outbreak and demonstration of intracellular multiplication of Legionella pneumophila.

At the site of a legionellosis outbreak, amoebae and two ciliates, Tetrahymena sp. and Cyclidium sp., were isolated from cooling-tower water containing Legionella pneumophila. The Tetrahymena sp. and the amoebae repeatedly showed the ability to support intracellular multiplication of L. pneumophila. Both were isolated from cooling towers specifically implicated as the source for the spread of legionellosis. These protozoa may be reservoirs supporting the survival and multiplication of virulent legionellae in cooling-tower water.     

Inhibition of platelet thromboxane A2 synthase activity by sodium 5-(3'-pyridinylmethyl)benzofuran-2-carboxylate

This report outlines the activity of a new thromboxane synthase inhibitor sodium, 5-(3-pyridinylmethyl)-2-benzofurancarboxylate, (U-63557A). U-63557A is a potent inhibitor of the thromboxane synthase in human platelets in vitro, as well as in rhesus monkey platelets ex vivo. A single oral dose of 3.0 mg/kg U-63557A inhibits the platelet thromboxane synthase in rhesus monkeys approximately 80% for at least 12 hrs. U-63557A has been administered to monkeys twice a day, (10 mg/kg) for 14 days, without evidence of drug tachyphylaxis or rebound. U-63557A does not inhibit thrombin-stimulated PGI2 biosynthesis in human endothelial cells, the 5-lipoxygenase in human neutrophils, or the cyclo-oxygenase in a variety of test systems. In anesthetized dogs, U-63557A injected i.v. at 0.1 to 5 mg/kg prevented the blockage of stenosed coronary arteries caused platelet aggregation. Similar effects were obtained by oral administration of 1-5 mg/kg. The thromboxane synthase inhibitor was more efficacious than cyclooxygenase inhibitors and equal to PGI2 in efficacy. Under appropriate conditions the protective effects of U-63557A could be reversed by i.v. cyclooxygenase inhibitors suggesting that its efficacy depended in part on endogenous PGI2 formation. Due to its specificity, oral activity, and extended duration of action, U-63557A is a promising compound for the evaluation of the role of thromboxane synthase in a variety of pathophysiological states.     

Heterogeneity of antibody response to Salmonella lipopolysaccharide measured by passive hemagglutination and hemolysis in mice

The complement-requiring passive hemolysis test with Salmonella typhimurium lipopolysaccharide-coated sheep erythrocytes is more sensitive for antibodies directed against the lipopolysaccharide than is the passive hemagglutination test. The hemagglutinating and hemolyzing antibodies produced in Swiss mice by hyperimmunization, either with or without Freund's adjuvant, were distributed in both the light and heavy fractions isolated by sucrose density gradient fractionation and gel filtration. IgM fractions, whether tested by hemagglutination or hemolysis, were sensitive to 2-mercaptoethanol (0.15 m). On the other hand, IgG hemolytic antibodies were more sensitive to 2-mercaptoethanol than were IgG hemagglutinating antibodies. The resistance of IgG hemagglutinating activity amounted to about 72 to 95% of the total IgG recovered, whereas the resistant portion of the IgG hemolytic activity was approximately 40 to 53%. It is suggested that, although mercaptoethanol sensitivity is not a definitive test for IgM antibody, its use in connection with the hemagglutination test gives at least an approximation of the IgG antibody, whereas the hemolysis test gives a better approximation of maximal measurable antibody against Salmonella lipopolysaccharides.     

Photosynthetic Electron Transport Chain of Chlamydomonas reinhardi. III. Light-Induced Absorbance Changes in Chloroplast Fragments of the Wild Type and Mutant Strains

Light-induced absorbance changes were investigated in chloroplast fragments of wild type Chlamydomonas reinhardi and 5 different mutant strains having impaired photosynthesis. Two absorbance changes were detected, 1 having a maximum at 553 nm and the other at 559 nm. The component exhibiting the 553 nm change is a cytochrome similar to cytochrome f from higher plant chloroplasts. The component exhibiting the 559 nm change has the properties of a cytochrome similar to cytochrome b(3). Two of the mutant strains (ac-115 and ac-141) were found to lack the 559 cytochrome and light induced only the oxidation of the 553 cytochrome. A third mutant strain (ac-206), previously shown to lack the 553 cytochrome, exhibited only the light-induced reduction of the 559 cytochrome. A fourth mutant strain (ac-208), shown to lack plastocyanin, exhibited absorbance changes attributable to both cytochromes. However, light was capable of inducing the reduction of the 559 cytochrome but not its oxidation. On the other hand, light induced the oxidation of the 553 cytochrome but not its reduction.These observations are discussed in terms of the series formulation for photosynthetic electron transport in which the 559 cytochrome is reduced by system II and transfers electrons via the component affected in ac-21 to the 553 cytochrome. Accordingly, system I sensitizes the oxidation of the 3 components of the electron transport chain.     

Photosynthetic Electron Transport Chain of Chlamydomonas reinhardi. V. Purification and Properties of Cytochrome 553 and Ferredoxin

Cytochrome 553 and ferredoxin were isolated and purified from acetone powders prepared from intact cells of the wild-type strain of Chlamydomonas reinhardi. Purification was achieved by ion exchange chromatography on DEAE cellulose and gel filtration on Sephadex G-75.     

Evolution of influenza A virus nucleoprotein genes: implications for the origins of H1N1 human and classical swine viruses

A phylogenetic analysis of 52 published and 37 new nucleoprotein (NP) gene sequences addressed the evolution and origin of human and swine influenza A viruses. H1N1 human and classical swine viruses (i.e., those related to Swine/Iowa/15/30) share a single common ancestor, which was estimated to have occurred in 1912 to 1913. From this common ancestor, human and classical swine virus NP genes have evolved at similar rates that are higher than in avian virus NP genes (3.31 to 3.41 versus 1.90 nucleotide changes per year). At the protein level, human virus NPs have evolved twice as fast as classical swine virus NPs (0.66 versus 0.34 amino acid change per year). Despite evidence of frequent interspecies transmission of human and classical swine viruses, our analysis indicates that these viruses have evolved independently since well before the first isolates in the early 1930s. Although our analysis cannot reveal the original host, the ancestor virus was avianlike, showing only five amino acid differences from the root of the avian virus NP lineage. The common pattern of relationship and origin for the NP and other genes of N1N1 human and classical swine viruses suggests that the common ancestor was an avian virus and not a reassortant derived from previous human or swine influenza A viruses. The new avianlike H1N1 swine viruses in Europe may provide a model for the evolution of newly introduced avian viruses into the swine host reservoir. The NPs of these viruses are evolving more rapidly than those of human or classical swine viruses (4.50 nucleotide changes and 0.74 amino acid change per year), and when these rates are applied to pre-1930s human and classical swine virus NPs, the predicted date of a common ancestor is 1918 rather than 1912 to 1913. Thus, our NP phylogeny is consistent with historical records and the proposal that a short time before 1918, a new H1N1 avianlike virus entered human or swine hosts (O. T. Gorman, R. O. Donis, Y. Kawaoka, and R. G. Webster, J. Virol. 64:4893-4902, 1990). This virus provided the ancestors of all known human influenza A virus genes, except for HA, NA, and PB1, which have since been reassorted from avian viruses. We propose that during 1918 a virulent strain of this new avianlike virus caused a severe human influenza pandemic and that the pandemic virus was introduced into North American swine populations, constituting the origin of classical swine virus.