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 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.     

Evolutionary analysis of the influenza A virus M gene with comparison of the M1 and M2 proteins

Phylogenetic analysis of 42 membrane protein (M) genes of influenza A viruses from a variety of hosts and geographic locations showed that these genes have evolved into at least four major host-related lineages: (i) A/Equine/prague/56, which has the most divergent M gene; (ii) a lineage containing only H13 gull viruses; (iii) a lineage containing both human and classical swine viruses; and (iv) an avian lineage subdivided into North American avian viruses (including recent equine viruses) and Old World avian viruses (including avianlike swine strains). The M gene evolutionary tree differs from those published for other influenza virus genes (e.g., PB1, PB2, PA, and NP) but shows the most similarity to the NP gene phylogeny. Separate analyses of the M1 and M2 genes and their products revealed very different patterns of evolution. Compared with other influenza virus genes (e.g., PB2 and NP), the M1 and M2 genes are evolving relatively slowly, especially the M1 gene. The M1 and M2 gene products, which are encoded in different but partially overlapping reading frames, revealed that the M1 protein is evolving very slowly in all lineages, whereas the M2 protein shows significant evolution in human and swine lineages but virtually none in avian lineages. The evolutionary rates of the M1 proteins were much lower than those of M2 proteins and other internal proteins of influenza viruses (e.g., PB2 and NP), while M2 proteins showed less rapid evolution compared with other surface proteins (e.g., H3HA). Our results also indicate that for influenza A viruses, the evolution of one protein of a bicistronic gene can affect the evolution of the other protein.(ABSTRACT TRUNCATED AT 400 WORDS)     

Proliferation of Legionella pneumophila as an intracellular parasite of the ciliated protozoan Tetrahymena pyriformis

In a series of experiments, we have determined that Legionella pneumophila will proliferate as an intracellular parasite of the ciliated holotrich Tetrahymena pyriformis in sterile tap water at 35 degrees C. After 7 days of incubation, serpentine chains of approximately 10(3) L. pneumophila cells were observed throughout the cytoplasm of the protozoan infected initially with 1 to 30 L. pneumophila cells. The overall L. pneumophila population increased from ca. 1.0 X 10(2) to ca. 5.0 X 10(4) cells per ml in the coculture within this time frame. The interactions between the protozoan and the bacterium appear to depend upon their concentrations as well as temperature of incubation. L. pneumophila did not multiply in sterile tap water alone, in suspensions of lysed T. pyriformis, or in cell-free filtrates of a T. pyriformis culture. In addition to establishing an ecological model, we found that addition of T. pyriformis to environmental specimens served as an enrichment method that improved isolation of legionella from the specimens.