Plant-Derived Polysaccharide Supplements Inhibit Dextran Sulfate Sodium-Induced Colitis in the Rat

Several plant-derived polysaccharides have been shown to have anti-inflammatory activity in animal models. Ambrotose complex and Advanced Ambrotose are dietary supplements that include aloe vera gel, arabinogalactan, fucoidan, and rice starch, all of which have shown such activity. This study was designed to evaluate these formulations against dextran sulfate sodium (DSS)-induced colitis in rats and to confirm their short-term safety after 14 days of daily dosing. Rats were dosed daily orally with vehicle, Ambrotose or Advanced Ambrotose. On day six groups of rats received tap water or 5% Dextran Sulfate sodium. Ambrotose and Advanced Ambrotose significantly lowered the disease scores and partially prevented the shortening of colon length. An increase in monocyte count was induced by dextran sulfate sodium and inhibited by Ambrotose and Advanced Ambrotose. There were no observable adverse effects after 14-day daily doses. The mechanism of action of the formulations against DSS-induced colitis may be related to its effect on monocyte count

Coronavirus Gene 7 Counteracts Host Defenses and Modulates Virus Virulence

Transmissible gastroenteritis virus (TGEV) genome contains three accessory genes: 3a, 3b and 7. Gene 7 is only present in members of coronavirus genus a1, and encodes a hydrophobic protein of 78 aa. To study gene 7 function, a recombinant TGEV virus lacking gene 7 was engineered (rTGEV-Δ7). Both the mutant and the parental (rTGEV-wt) viruses showed the same growth and viral RNA accumulation kinetics in tissue cultures. Nevertheless, cells infected with rTGEV-Δ7 virus showed an increased cytopathic effect caused by an enhanced apoptosis mediated by caspase activation. Macromolecular synthesis analysis showed that rTGEV-Δ7 virus infection led to host translational shut-off and increased cellular RNA degradation compared with rTGEV-wt infection. An increase of eukaryotic translation initiation factor 2 (eIF2α) phosphorylation and an enhanced nuclease, most likely RNase L, activity were observed in rTGEV-Δ7 virus infected cells. These results suggested that the removal of gene 7 promoted an intensified dsRNA-activated host antiviral response. In protein 7 a conserved sequence motif that potentially mediates binding to protein phosphatase 1 catalytic subunit (PP1c), a key regulator of the cell antiviral defenses, was identified. We postulated that TGEV protein 7 may counteract host antiviral response by its association with PP1c. In fact, pull-down assays demonstrated the interaction between TGEV protein 7, but not a protein 7 mutant lacking PP1c binding motif, with PP1. Moreover, the interaction between protein 7 and PP1 was required, during the infection, for eIF2α dephosphorylation and inhibition of cell RNA degradation. Inoculation of newborn piglets with rTGEV-Δ7 and rTGEV-wt viruses showed that rTGEV-Δ7 virus presented accelerated growth kinetics and pathology compared with the parental virus. Overall, the results indicated that gene 7 counteracted host cell defenses, and modified TGEV persistence increasing TGEV survival. Therefore, the acquisition of gene 7 by the TGEV genome most likely has provided a selective advantage to the virus

ON THE MARINE ALGAE OF KENT ISLAND BAY OF FUNDY

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Repair and mutagenesis of the genome of a deletion mutant of the coronavirus mouse hepatitis virus by targeted RNA recombination

The genetic characterization of a nucleocapsid (N) protein mutant of the coronavirus mouse hepatitis virus (MHV) is described. The mutant, Albany 4 (Alb4), is both temperature sensitive and thermolabile. Analysis of the progeny of a mixed infection showed that the defective Alb4 allele is recessive to wild type, and its gene product is diffusible. The N protein of Alb4 was found to be smaller than its wild-type counterpart, and sequence analysis of the Alb4 N gene revealed that it contains an internal deletion of 87 nucleotides, producing an in-frame deletion of 29 amino acids. All of these properties of Alb4 made it ideal for use as a recipient in a targeted RNA recombination experiment in which the deletion in Alb4 was repaired by recombination with synthetic RNA7, the smallest MHV subgenomic mRNA. Progeny from a cotransfection of Alb4 genomic RNA and synthetic RNA7 were selected for thermal stability. Polymerase chain reaction analysis of candidate recombinants showed that they had regained the material that is deleted in the Alb4 mutant. They also had acquired a five-nucleotide insertion in the 3' untranslated region, which had been incorporated into the synthetic RNA7 as a molecular tag. The presence of the tag was directly verified, as well, by sequencing the genomic RNA of purified recombinant viruses. This provided a clear genetic proof that the Alb4 phenotype was due to the observed deletion in the N gene. In addition, these results demonstrated that it is possible to obtain stable, independently replicating progeny from recombination between coronavirus genomic RNA and a tailored, synthetic RNA species.</jats:p