The innate immune system provides a first line of defense against invading pathogens by releasing multiple inflammatory cytokines, such as interleukin-1β and tumor necrosis factor-α, which directly combat the infectious agent and recruit additional immune responses. This exuberant cytokine release paradoxically injures the host by triggering leakage from capillaries, tissue edema, organ failure, and shock. Current medical therapies target individual pathogens with antimicrobial agents or directly either blunt or boost the host's immune system. We explored a third approach: activating with the soluble ligand Slit an endothelium-specific, Robo4-dependent signaling pathway that strengthens the vascular barrier, diminishing deleterious aspects of the host's response to the pathogen-induced cytokine storm. This approach reduced vascular permeability in the lung and other organs and increased survival in animal models of bacterial endotoxin exposure, polymicrobial sepsis, and H5N1

IFN-α-n3) did not significantly reduce lung virus titres in mice. Anti-inflammatory agents, chloroquine, amodiaquin and pentoxifylline, were also inactive in vivo, suggesting that although they may be useful in ameliorating the hyperinflammatory response induced by the virus infection, they will not significantly reduce the replication of the virus, the inducer of inflammatory response. Thus, anti-inflammatory agents may only be useful in treating virus lung infections if used in combination with agents that inhibit virus replication. In summary, the data suggest that induction of IFN by mismatched dsRNA or actual treatment with exogenous IFN-α can inhibit SARS-CoV replication in the lungs of mice.

Severe acute respiratory syndrome (SARS) is a highly lethal emerging disease caused by coronavirus SARS-CoV. New lethal animal models for SARS were needed to facilitate antiviral research. We adapted and characterized a new strain of SARS-CoV (strain v2163) that was highly lethal in 5–6 week old BALB/c mice. It had nine mutations affecting 10 amino acid residues. Strain v2163 increased IL-1α, IL-6, MIP-1α, MCP-1, and RANTES in mice, and high IL-6 expression correlated with mortality. The infection largely mimicked human disease, but lung pathology lacked hyaline membrane formation. In vitro efficacy against v2163 was shown with known inhihibitors of SARS-CoV replication. In v2163-infected mice, Ampligen™ was fully protective, stinging nettle lectin (UDA) was partially protective, ribavirin was disputable and possibly exacerbated disease, and EP128533 was inactive. Ribavirin, UDA and Ampligen™ decreased IL-6 expression. Strain v2163 provided a valuable model for anti-SARS research.

Background Oxygen exists in two gaseous and six solid allotropic modifications. An additional allotropic modification of oxygen, the cyclooctaoxygen, was predicted to exist in 1990. Methods Cyclooctaoxygen sodium was synthesized in vitro from atmospheric oxygen, or catalase effect-generated oxygen, under catalysis of cytosine nucleosides and either ninhydrin or eukaryotic low-molecular weight RNA. Thin-layer chromatographic mobility shift assays were applied on specific nucleic acids and the cyclooctaoxygen sodium complex. Results We report the first synthesis and characterization of cyclooctaoxygen as its sodium crown complex, isolated in the form of three cytosine nucleoside hydrochloride complexes. The cationic cyclooctaoxygen sodium complex is shown to bind to nucleic acids (RNA and DNA), to associate with single-stranded DNA and spermine phosphate, and to be essentially non-toxic to cultured mammalian cells at 0.1–1.0 mM concentration. Conclusions We postulate that cyclooctaoxygen is formed in most eukaryotic cells in vivo from dihydrogen peroxide in a catalase reaction catalyzed by cytidine and RNA. A molecular biological model is deduced for a first epigenetic shell of eukaryotic in vivo DNA. This model incorporates an epigenetic explanation for the interactions of the essential micronutrient selenium (as selenite) with eukaryotic in vivo DNA. General significance Since the sperminium phosphate/cyclooctaoxygen sodium complex is calculated to cover the active regions (2.6%) of bovine lymphocyte interphase genome, and 12.4% of murine enterocyte mitotic chromatin, we propose that the sperminium phosphate/cyclooctaoxygen sodium complex coverage of nucleic acids is essential to eukaryotic gene regulation and promoted proto-eukaryotic evolution.

T-705 (6-fluoro-3-hydroxy-2-pyrazinecarboxamide) was inhibitory to four strains of avian H5N1 influenza virus in MDCK cells, with the 90% effective concentrations ranging from 1.3 to 7.7 M, as determined by a virus yield reduction assay. The efficacy was less than that exerted by oseltamivir carboxylate or zanamivir but was greater than that exerted by ribavirin. Experiments with mice lethally infected with influenza A/Duck/ MN/1525/81 (H5N1) virus showed that T-705 administered per os once, twice, or four times daily for 5 days beginning 1 h after virus exposure was highly inhibitory to the infection. Dosages from 30 to 300 mg/kg of body weight/day were well tolerated; each prevented death, lessened the decline of arterial oxygen saturation (SaO 2 ), and inhibited lung consolidation and lung virus titers. Dosages from 30 to 300 mg/kg/day administered once or twice daily also significantly prevented the death of the mice. Oseltamivir (20 mg/kg/day), administered per os twice daily for 5 days, was tested in parallel in two experiments; it was only weakly effective against the infection. The four-times-daily T-705 treatments at 300 mg/kg/day could be delayed until 96 h after virus exposure and still significantly inhibit the infection. Single T-705 treatments administered up to 60 h after virus exposure also prevented death and the decline of SaO 2 . Characterization of the pathogenesis of the duck influenza H5N1 virus used in these studies was undertaken; although the virus was highly pathogenic to mice, it was less neurotropic than has been described for clinical isolates of the H5N1 virus. These data indicate that T-705 may be useful for the treatment of avian influenza virus infections.