Study on the Interaction of Algal Peptides on Virulence Factors of Helicobacter pylori: In Silico Approach.

In the Asian region, Helicobacter pylori infects about 80% populations, which is most leading cause of peptic ulcers, and it is an asymptomatic infection. Studies reported that the particular bacteria carry specific virulence factors that leads to severe complications. These virulence factors can be used as a drug targets to inhibit their growth and pathogenicity. Chronic infection with H. pylori virulence factors are CagA, VacA and HtrA positive strains the risk factor of gastric cancer. In this study, we aimed to study the antagonistic interaction pattern between the potential eight algal peptides against the virulence factors of H. pylori through in silico analysis intended to treat peptic ulcer and prevent the further complications such as cancer. The proteins of virulent factors are docked using C-Docker algorithm and calculated the bind energy of the complexes. The results showed that the peptide derived from a green alga, Tetradesmus sp. are active against the three virulent factors such as cag-A, vac-A, and Htr-A with multiple hydrogen, vdW, electrostatic interactions, and mild π-hydrophobic bindings with the libdock energy score for CagA, VacA and HtrA are 175.625, 158.603 and 89.397 kcal/mol. These primes and the peptide lead to develop a better and potential inhibitors against H. pylori infection.

Pyropia yezoensis protein protects against TNF­α­induced myotube atrophy in C2C12 myotubes via the NF­κB signaling pathway.

The protein extracted from red algae Pyropia yezoensis has various biological activities, including anti­inflammatory, anticancer, antioxidant, and antiobesity properties. However, the effects of P. yezoensis protein (PYCP) on tumor necrosis factor­α (TNF­α)­induced muscle atrophy are unknown. Therefore, the present study investigated the protective effects and related mechanisms of PYCP against TNF­α­induced myotube atrophy in C2C12 myotubes. Treatment with TNF­α (20 ng/ml) for 48 h significantly reduced myotube viability and diameter and increased intracellular reactive oxygen species levels; these effects were significantly reversed in a dose­dependent manner following treatment with 25­100 µg/ml PYCP. PYCP inhibited the expression of TNF receptor­1 in TNF­α­induced myotubes. In addition, PYCP markedly downregulated the nuclear translocation of nuclear factor­κB (NF­κB) by inhibiting the phosphorylation of inhibitor of κB. Furthermore, PYCP treatment suppressed 20S proteasome activity, IL­6 production, and the expression of the E3 ubiquitin ligases, atrogin­1/muscle atrophy F­box and muscle RING­finger protein­1. Finally, PYCP treatment increased the protein expression levels of myoblast determination protein 1 and myogenin in TNF­α­induced myotubes. The present findings indicate that PYCP may protect against TNF­α­induced myotube atrophy by inhibiting the proinflammatory NF­κB pathway.

Cyanobacteria and Eukaryotic Microalgae as Emerging Sources of Antibacterial Peptides.

Cyanobacteria and microalgae are oxygen-producing photosynthetic unicellular organisms encompassing a great diversity of species, which are able to grow under all types of extreme environments and exposed to a wide variety of predators and microbial pathogens. The antibacterial compounds described for these organisms include alkaloids, fatty acids, indoles, macrolides, peptides, phenols, pigments and terpenes, among others. This review presents an overview of antibacterial peptides isolated from cyanobacteria and microalgae, as well as their synergism and mechanisms of action described so far. Antibacterial cyanopeptides belong to different orders, but mainly from Oscillatoriales and Nostocales. Cyanopeptides have different structures but are mainly cyclic peptides. This vast peptide repertoire includes ribosomal and abundant non-ribosomal peptides, evaluated by standard conventional methodologies against pathogenic Gram-negative and Gram-positive bacteria. The antibacterial activity described for microalgal peptides is considerably scarcer, and limited to protein hydrolysates from two Chlorella species, and few peptides from Tetraselmis suecica. Despite the promising applications of antibacterial peptides and the importance of searching for new natural sources of antibiotics, limitations still persist for their pharmaceutical applications.

Dietary osteopontin-enriched algal protein as nutritional support in weaned pigs infected with F18-fimbriated enterotoxigenic Escherichia coli.

This study investigated the effects of dietary osteopontin (OPN)-enriched algal protein on growth, immune status, and fecal fermentation profiles of weaned pigs challenged with a live infection of F18-fimbriated enterotoxigenic E. coli (ETEC). At 21 d of age, 54 pigs (5.95 ± 0.28 kg BW; blocked by BW) were allotted to 1 of 3 experimental groups combining dietary and health statuses. A control diet, containing 1% wild-type algal protein, was fed to both sham-inoculated (NC) and ETEC-inoculated (PC) pigs, while the test diet contained 1% OPN-enriched algal protein as fed only to ETEC-inoculated pigs (OA). All pigs received their assigned dietary treatment starting at study initiation to permit a 10-d acclimation period prior to inoculation. Growth performance, fecal dry matter, as well as hematological, histopathological, immune, and microbiota outcomes were analyzed by ANOVA, where treatment and time were considered as fixed effects and pig as a random effect; significance was accepted at P < 0.05. Overall, ETEC-inoculated pigs (PC and OA) exhibited decreased (P < 0.05) ADG and G:F, as well as increased (P < 0.05) peripheral blood helper T-cells and total leukocyte counts, compared with NC pigs during the postinoculation period. The OA treatment also elicited the highest (P < 0.05) concentrations of circulating tumor necrosis factor-α and volatile fatty acid concentrations in luminal contents at various postinoculation time-points, compared with other treatments. A principal coordinate analysis based on Unifrac weighted distances indicated that NC and OA groups had similar overall bacterial community structures, while PC pigs exhibited greater diversity, but infection status had no impact on α-diversity. Osteopontin-specific effects on microbial community structure included enrichment within Streptococcus and Blautia genera and decreased abundance of 12 other genera as compared with PC pigs. Overall, ETEC-infected pigs receiving 1% OPN-enriched algal protein exhibited changes immunity, inflammatory status, and colonic microbial community structure that may benefit weanling pigs experiencing F18 ETEC infection.

Phycocyanin Extracted from Oscillatoria minima Shows Antimicrobial, Algicidal, and Antiradical Activities: In silico and In vitro Analysis.

BACKGROUND: Phycocyanin is an algae-derived protein, which binds to pigment for harvesting light. It has been reported in various different species, including that of red algae, dinoflagellates, and cryptophyta. Importantly, phycocyanin has enormous applications, including cosmetic colorant, food additive, biotechnology, diagnostics, fluorescence detection probe, an anticancer agent, anti-inflammatory, immune enhancer, etc. In addition, several different algae were utilized for the isolation of cyano-phycocyanin (C-PC), but most of the purification methods consist of several steps of crude extraction. AIM: To isolate C-PC from a new source of microalgae with better purity level and to evaluate its antimicrobial, algicidal, and antiradical activities. METHODS: Biological activity, permeability, pharmacokinetics, and toxicity profile of C-PC were predicted by in silico studies. C-PC was purified and isolated by using ammonium sulphate precipitation, ion-exchange chromatography and gel-filtration chromatography. C-PC was characterized by SDS-PAGE and elution profile (purity ratio) analysis. Antimicrobial and algicial activities of C-PC were evaluated by the microtitre plate based assays. Antiradical activity of C-PC was evaluated by DPPH- and ABTS*+ radical scavenging assays. CONCLUSION: C-PC was extracted from Oscillatoria minima for the first time, followed by its quantitative as well qualitative evaluation, indicating a new alternative source of this important protein. Furthermore, the antimicrobial, algicidal, and antiradical activities of the isolated C-PC extract have been demonstrated by both in silico as well as in vitro methods.

Spirulina Crude Protein Promotes the Migration and Proliferation in IEC-6 Cells by Activating EGFR/MAPK Signaling Pathway.

Spirulina is a type of filamentous blue-green microalgae known to be rich in nutrients and to have pharmacological effects, but the effect of spirulina on the small intestine epithelium is not well understood. Therefore, this study aims to investigate the proliferative effects of spirulina crude protein (SPCP) on a rat intestinal epithelial cells IEC-6 to elucidate the mechanisms underlying its effect. First, the results of wound-healing and cell viability assays demonstrated that SPCP promoted migration and proliferation in a dose-dependent manner. Subsequently, when the mechanisms of migration and proliferation promotion by SPCP were confirmed, we found that the epidermal growth factor receptor (EGFR) and mitogen-activated protein (MAPK) signaling pathways were activated by phosphorylation. Cell cycle progression from G0/G1 to S phase was also promoted by SPCP through upregulation of the expression levels of cyclins and cyclin-dependent kinases (Cdks), which regulate cell cycle progression to the S phase. Meanwhile, the expression of cyclin-dependent kinase inhibitors (CKIs), such as p21 and p27, decreased with SPCP. In conclusion, our results indicate that activation of EGFR and its downstream signaling pathway by SPCP treatment regulates cell cycle progression. Therefore, these results contribute to the research on the molecular mechanism for SPCP promoting the migration and proliferation of rat intestinal epithelial cells.

Isolation and identification of anti-proliferative peptides from Spirulina platensis using three-step hydrolysis.

BACKGROUND: Spirulina platensis is an excellent source of proteins (>60%) that can be hydrolyzed into bioactive peptides. RESULTS: In this study, whole proteins of Spirulina platensis were extracted and hydrolyzed using three gastrointestinal endopeptidases (pepsin, trypsin and chymotrypsin). Subsequently, gel filtration chromatography was employed to separate hydrolysates, and four fractions (Tr1-Tr4) were obtained. Among them, Tr2 showed the strongest anti-proliferation activities on three cancer cells (MCF-7, HepG-2 and SGC-7901), with IC50 values of <31.25, 36.42 and 48.25 µg mL-1 , respectively. Furthermore, a new peptide, HVLSRAPR, was identified from fraction Tr1. This peptide exhibited strong inhibition on HT-29 cancer cells with an IC50 value of 99.88 µg mL-1 . CONCLUSION: Taken together, these peptides possessed anti-proliferation activities on cancer cells and low cytotoxicity on normal cells, suggesting that they might serve as a natural anticancer agent for nutraceutical and pharmaceutical industries. © 2016 Society of Chemical Industry.

Griffithsin-Modified Electrospun Fibers as a Delivery Scaffold To Prevent HIV Infection.

Despite current prophylactic strategies, sexually transmitted infections (STIs) remain significant contributors to global health challenges, spurring the development of new multipurpose delivery technologies to protect individuals from and treat virus infections. However, there are few methods currently available to prevent and no method to date that cures human immunodeficiency virus (HIV) infection or combinations of STIs. While current oral and topical preexposure prophylaxes have protected against HIV infection, they have primarily relied on antiretrovirals (ARVs) to inhibit infection. Yet continued challenges with ARVs include user adherence to daily treatment regimens and the potential toxicity and antiviral resistance associated with chronic use. The integration of new biological agents may avert some of these adverse effects while also providing new mechanisms to prevent infection. Of the biologic-based antivirals, griffithsin (GRFT) has demonstrated potent inhibition of HIV-1 (and a multitude of other viruses) by adhering to and inactivating HIV-1 immediately upon contact. In parallel with the development of GRFT, electrospun fibers (EFs) have emerged as a promising platform for the delivery of agents active against HIV infection. In the study described here, our goal was to extend the mechanistic diversity of active agents and electrospun fibers by incorporating the biologic GRFT on the EF surface rather than within the EFs to inactivate HIV prior to cellular entry. We fabricated and characterized GRFT-modified EFs (GRFT-EFs) with different surface modification densities of GRFT and demonstrated their safety and efficacy against HIV-1 infection in vitro We believe that EFs are a unique platform that may be enhanced by incorporation of additional antiviral agents to prevent STIs via multiple mechanisms.

An S-type anion channel SLAC1 is involved in cryptogein-induced ion fluxes and modulates hypersensitive responses in tobacco BY-2 cells.

Pharmacological evidence suggests that anion channel-mediated plasma membrane anion effluxes are crucial in early defense signaling to induce immune responses and hypersensitive cell death in plants. However, their molecular bases and regulation remain largely unknown. We overexpressed Arabidopsis SLAC1, an S-type anion channel involved in stomatal closure, in cultured tobacco BY-2 cells and analyzed the effect on cryptogein-induced defense responses including fluxes of Cl(-) and other ions, production of reactive oxygen species (ROS), gene expression and hypersensitive responses. The SLAC1-GFP fusion protein was localized at the plasma membrane in BY-2 cells. Overexpression of SLAC1 enhanced cryptogein-induced Cl(-) efflux and extracellular alkalinization as well as rapid/transient and slow/prolonged phases of NADPH oxidase-mediated ROS production, which was suppressed by an anion channel inhibitor, DIDS. The overexpressor also showed enhanced sensitivity to cryptogein to induce downstream immune responses, including the induction of defense marker genes and the hypersensitive cell death. These results suggest that SLAC1 expressed in BY-2 cells mediates cryptogein-induced plasma membrane Cl(-) efflux to positively modulate the elicitor-triggered activation of other ion fluxes, ROS as well as a wide range of defense signaling pathways. These findings shed light on the possible involvement of the SLAC/SLAH family anion channels in cryptogein signaling to trigger the plasma membrane ion channel cascade in the plant defense signal transduction network.

Molecular characteristics and biological activities of anionic macromolecules from Codium fragile.

Water-soluble anionic macromolecules isolated from Codium fragile and fractionated using ion-exchange chromatography were investigated to determine their molecular characteristics and immunostimulating activity. The crude molecules and fractions (F1, F2, and F3) consisted mostly of carbohydrates (44.1-80.5%), sulfates (3.2-22.2%) and proteins (3.0-15.7%) with small amounts of uronic acids (1.1-4.2%), and included different levels of mannose (91.3-18.7%), glucose (62.7-8.6%) and galactose (37.5-59.5%). These molecules contained one or two subfractions with molecular weights (Mw) ranging from 148×10(3) to 4879×10(3)g/mol. The crude, F1 and F2 stimulated RAW264.7 cells to produce considerable amounts of pro-inflammatory mediator nitric oxide (NO) and cytokines. The treatment of sample molecules facilitated the degradation of Iκ-B and phosphorylation of MAPK in RAW264.7 cells, suggesting that they might stimulate RAW264.7 cells through the activation of NF-κB and MAPK pathway. Proteins in fraction F2 were essential to possess its bioactivity and its main backbone was composed of mixed linkages of (1→3)-α and ß-d-mannan.

Induction of apoptosis signaling by glycoprotein of Capsosiphon fulvescens in human gastric cancer (AGS) cells.

Capsosiphon fulvescens is a well-known green sea algae that has been touted in recent years as a potential anticancer drug. In this study, C. fulvescens glycoprotein (Cf-GP) showed proapoptotic signaling in AGS cells. An MTS assay indicated that Cf-GP inhibited the proliferation of AGS cell lines in a dose-dependent manner. Cells were treated with Cf-GP and the expression of proteins associated with apoptosis was examined by Western blotting. Based on the Western blot, expression of Cf-GP-activated caspase-cascade and PARP, which is a substrate of caspase-3 and -8, and proteins of the Bcl-2 family was observed. Cf-GP treatment stimulated the release of cytochrome C and apoptotic protease activating factor-1 from mitochondria to the cytosol. Cf-GP inhibited the growth of AGS cells through induction of sub-G1 phase arrest. We confirmed that sub-G1-phase arrest was associated with a decrease in the expression of cyclin D, cyclin E, Cdk2, Cdk4, and Cdk6, and an increase in the protein levels of p21 and p27. As a result, the increased sub-G1 ratio appears to be inhibited by cell proliferation. Therefore, we can confirm apoptosis in the AGS cells. Our results suggest that Cf-GP could be a potential source of biofunctional material that shows anticancer effects in human gastrointestinal cancer.

Griffithsin has antiviral activity against hepatitis C virus.

Hepatitis C virus (HCV)-infected patients undergoing liver transplantation universally experience rapid reinfection of their new liver graft. Current treatment protocols do not prevent graft reinfection and, in addition, an accelerated disease progression is observed. In the present study, we have evaluated a novel strategy to prevent HCV infection using a lectin, griffithsin (GRFT) that specifically binds N-linked high-mannose oligosaccharides that are present on the viral envelope. The antiviral effect of GRFT was evaluated in vitro using the HCV pseudoparticle (HCVpp) and HCV cell culture (HCVcc) systems. We show here that preincubation of HCVpp and HCVcc with GRFT prevents infection of Huh-7 hepatoma cells. Furthermore, GRFT interferes with direct cell-to-cell transmission of HCV. GRFT acts at an early phase of the viral life cycle by interfering in a genotype-independent fashion with the interaction between the viral envelope proteins and the viral receptor CD81. The capacity of GRFT to prevent infection in vivo was evaluated using uPA(+/+)-SCID mice (uPA stands for urokinase-type plasminogen activator) that harbor human primary hepatocytes in their liver (chimeric mice). In this proof-of-concept trial, we demonstrated that GRFT can mitigate HCV infection of chimeric mice. Treated animals that did become infected demonstrated a considerable delay in the kinetics of the viral infection. Our data demonstrate that GRFT can prevent HCV infection in vitro and mitigate HCV infection in vivo. GRFT treatment of chronically infected HCV patients undergoing liver transplantation may be a suitable strategy to prevent infection of the liver allograft.

Type-2 histone deacetylases as new regulators of elicitor-induced cell death in plants.

• Plant resistance to pathogen attack is often associated with a localized programmed cell death called hypersensitive response (HR). How this cell death is controlled remains largely unknown. • Upon treatment with cryptogein, an elicitor of tobacco defence and cell death, we identified NtHD2a and NtHD2b, two redundant isoforms of type-2 nuclear histone deacetylases (HDACs). These HDACs are phosphorylated after a few minutes' treatment, and their rate of mRNAs are rapidly and strongly reduced, leading to a 40-fold decrease after 10 h of treatment. • By using HDAC inhibitors, RNAi- and overexpression-based approaches, we showed that HDACs, and especially NtHD2a/b, act as inhibitors of cryptogein-induced cell death. Moreover, in NtHD2a/b-silenced plants, infiltration with cryptogein led to HR-like symptoms in distal leaves. • Taken together, these results show for the first time that type-2 HDACs, which are specific to plants, act as negative regulators of elicitor-induced cell death in tobacco (Nicotiana tabacum), suggesting that the HR is controlled by post-translational modifications including (de)acetylation of nuclear proteins.

Cryptogein-induced cell cycle arrest at G2 phase is associated with inhibition of cyclin-dependent kinases, suppression of expression of cell cycle-related genes and protein degradation in synchronized tobacco BY-2 cells.

Induction of defense responses by pathogens or elicitors is often accompanied by growth inhibition in planta, but its molecular mechanisms are poorly understood. In this report, we characterized the molecular events that occur during cryptogein-induced cell cycle arrest at G(2) phase in synchronously cultured tobacco Bright Yellow-2 (BY-2) cells. Concomitant with the proteinaceous elicitor-induced G(2) arrest, we observed inhibition of the histone H1 kinase activity of cyclin-dependent kinases (CDKs), which correlated with a decrease in mRNA and protein levels of CDKB1. In contrast, the amount of CDKA was almost unaffected by cryptogein even at M phase. Cryptogein rapidly inhibited the expression not only of positive, e.g. A- and B-type cyclins and NtCAK, but also of negative cell cycle regulators such as WEE1, suggesting that cryptogein affects multiple targets to inactivate CDKA to induce G(2) arrest by mechanisms distinct from known checkpoint regulation. Moreover, we show that CDKB1 and cyclin proteins are also rapidly degraded by cryptogein and that the proteasome-dependent protein degradation has a crucial role in the control of cryptogein-induced hypersensitive cell death.

Involvement of putative glutamate receptors in plant defence signaling and NO production.

Ionotropic glutamate receptors (iGluRs) are non-selective cation channels permeable to calcium, present in animals and plants. In mammals, glutamate is a well-known neurotransmitter and recently has been recognized as an immunomodulator. As animals and plants share common mechanisms that govern innate immunity with calcium playing a key role in plant defence activation, we have checked the involvement of putative iGluRs in plant defence signaling. Using tobacco cells, we first provide evidence supporting the activity of iGluRs as calcium channels and their involvement in NO production as reported in animals. Thereafter, iGluRs were shown to be activated in response to cryptogein, a well studied elicitor of defence response, and partly responsible for cryptogein-induced NO production. However, other cryptogein-induced calcium-dependent events including anion efflux, H(2)O(2) production, MAPK activation and hypersensitive response (HR) did not depend on iGluRs indicating that different calcium channels regulate different processes at the cell level. We have also demonstrated that cryptogein induces efflux of glutamate in the apoplast by exocytosis. Taken together, our results demonstrate for the first time, an involvement of a putative iGluR in plant defence signaling and NO production, by mechanisms that show homology with glutamate mode of action in mammals.

Potent strategy to inhibit HIV-1 by binding both gp120 and gp41.

The development of an anti-HIV microbicide is critical in the fight against the spread of HIV. It is shown here that the covalent linking of compounds that bind gp120 with compounds that bind gp41 can inhibit HIV entry even more potently than individual inhibitors or noncovalent combinations. The most striking example involves griffithsin, a potent HIV inhibitor that binds to the surface of HIV gp120. While griffithsin inhibits HIV Env-mediated fusion in a CCR5-tropic cell-cell fusion assay with a 50% inhibitory concentration (IC(50)) of 1.31 ± 0.87 nM and the gp41-binding peptide C37 shows an IC(50) of 18.2 ± 7.6 nM, the covalently linked combination of griffithsin with C37 (Griff37) has an IC(50) of 0.15 ± 0.05 nM, exhibiting a potency 8.7-fold greater than that of griffithsin alone. Similarly, in CXCR4-tropic cell-cell fusion assays, Griff37 is 5.2-fold more potent than griffithsin alone. In viral assays, both griffithsin and Griff37 inhibit HIV replication at midpicomolar levels, but the linked compound Griff37 is severalfold more potent than griffithsin alone against both CCR5- and CXCR4-tropic virus strains. Another example of this strategy is the covalently linked combination of peptide C37 with a variant of the gp120-binding peptide CD4M33 (L. Martin et al., Nat. Biotechnol. 21:71-76, 2003). Also, nuclear magnetic resonance (NMR) spectra for several of these compounds are shown, including, to our knowledge, the first published NMR spectrum for griffithsin.

Cryptogein, a fungal elicitor, remodels the phenylpropanoid metabolism of tobacco cell suspension cultures in a calcium-dependent manner.

Plant cells use calcium-based signalling pathways to transduce biotic and/or abiotic stimuli into adaptive responses. However, little is known about the coupling between calcium signalling, transcriptional regulation and the downstream biochemical processes. To understand these relationships better, we challenged tobacco BY-2 cells with cryptogein and evaluated how calcium transients (monitored through the calcium sensor aequorin) impact (1) transcript levels of phenylpropanoid genes (assessed by RT-qPCR); and (2) derived-phenolic compounds (analysed by mass spectrometry). Most genes of the phenylpropanoid pathway were up-regulated by cryptogein and cell wall-bound phenolic compounds accumulated (mainly 5-hydroxyferulic acid). The accumulation of both transcripts and phenolics was calcium-dependent. The transcriptional regulation of phenylpropanoid genes was correlated in a non-linear manner with stimulus intensity and with components of the cryptogein-induced calcium signature. In addition, calmodulin inhibitors increased the sensitivity of cells to low concentrations of cryptogein. These results led us to propose a model of coupling between the cryptogein signal, calcium signalling and the transcriptional response, exerting control of transcription through the coordinated action of two decoding modules exerting opposite effects.

Anticancer and antioxidant activities of the peptide fraction from algae protein waste.

Algae protein waste is a byproduct during production of algae essence from Chlorella vulgaris. There is no known report on the anticancer peptides derived from the microalgae protein waste. In this paper, the peptide fraction isolated from pepsin hydrolysate of algae protein waste had strong dose-dependent antiproliferation and induced a post-G1 cell cycle arrest in AGS cells; however, no cytotoxicity was observed in WI-38 lung fibroblasts cells in vitro. The peptide fraction also revealed much better antioxidant activity toward peroxyl radicals and LDL than those of Trolox. Among these peptides, a potent antiproliferative, antioxidant, and NO-production-inhibiting hendecapeptide was isolated, and its amino acid sequence was VECYGPNRPQF. These results demonstrate that inexpensive algae protein waste could be a new alternative to produce anticancer peptides.

Broad-spectrum in vitro activity and in vivo efficacy of the antiviral protein griffithsin against emerging viruses of the family Coronaviridae.

Viruses of the family Coronaviridae have recently emerged through zoonotic transmission to become serious human pathogens. The pathogenic agent responsible for severe acute respiratory syndrome (SARS), the SARS coronavirus (SARS-CoV), is a member of this large family of positive-strand RNA viruses that cause a spectrum of disease in humans, other mammals, and birds. Since the publicized outbreaks of SARS in China and Canada in 2002-2003, significant efforts successfully identified the causative agent, host cell receptor(s), and many of the pathogenic mechanisms underlying SARS. With this greater understanding of SARS-CoV biology, many researchers have sought to identify agents for the treatment of SARS. Here we report the utility of the potent antiviral protein griffithsin (GRFT) in the prevention of SARS-CoV infection both in vitro and in vivo. We also show that GRFT specifically binds to the SARS-CoV spike glycoprotein and inhibits viral entry. In addition, we report the activity of GRFT against a variety of additional coronaviruses that infect humans, other mammals, and birds. Finally, we show that GRFT treatment has a positive effect on morbidity and mortality in a lethal infection model using a mouse-adapted SARS-CoV and also specifically inhibits deleterious aspects of the host immunological response to SARS infection in mammals.

Phylogenetically-based variation in the regulation of the Calvin cycle enzymes, phosphoribulokinase and glyceraldehyde-3-phosphate dehydrogenase, in algae.

Aquatic photosynthesis is responsible for about half of the global production and is undertaken by a huge phylogenetic diversity of algae that are poorly studied. The diversity of redox-regulation of phosphoribulokinase (PRK) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was investigated in a wide range of algal groups under standard conditions. Redox-regulation of PRK was greatest in chlorophytes, low or absent in a red alga and most chromalveolates, and linked to the number of amino acids between two regulatory cysteine residues. GAPDH regulation was not strongly-related to the different forms of this enzyme and was less variable than for PRK. Addition of recombinant CP12, a protein that forms a complex with PRK and GAPDH, to crude extracts inhibited GAPDH and PRK inversely in the Plantae, but in most chromalveolates had little effect on GAPDH and inhibited or stimulated PRK depending on the species. Patterns of enzyme regulation were used to produce a phylogenetic tree in which cryptophytes and haptophytes, at the base of the chromalveolates, formed a distinct clade. A second clade comprised only chromalveolates. A third clade comprised a mixture of Plantae, an excavate and three chromalveolates: a marine diatom and two others (a xanthophyte and eustigmatophyte) that are distinguished by a low content of chlorophyll c and a lack of fucoxanthin. Regulation of both enzymes was greater in freshwater than in marine taxa, possibly because most freshwaters are more dynamic than oceans. This work highlights the importance of understanding enzyme regulation in diverse algae if their ecology and productivity is to be understood.