Application of regulation of reactive oxygen species and lipid peroxidation to disease treatment.

Although many diseases in which reactive oxygen species (ROS) and free radicals are involved in their pathogenesis are known, and antioxidants that effectively capture ROS have been identified and developed, there are only a few diseases for which antioxidants have been used for treatment. Here, we discuss on the following four concepts regarding the development of applications for disease treatment by regulating ROS, free radicals, and lipid oxidation with the findings of our research and previous reports. Concept 1) Utilization of antioxidants for disease treatment. In particular, the importance of the timing of starting antioxidant will be discussed. Concept 2) Therapeutic strategies using ROS and free radicals. Methods of inducing ferroptosis, which has been advocated as an iron-dependent cell death, are mentioned. Concept 3) Treatment with drugs that inhibit the synthesis of lipid mediators. In addition to the reduction of inflammatory lipid mediators by inhibiting cyclooxygenase and leukotriene synthesis, we will introduce the possibility of disease treatment with lipoxygenase inhibitors. Concept 4) Disease treatment by inducing the production of useful lipid mediators for disease control. We describe the treatment of inflammatory diseases utilizing pro-resolving mediators and propose potential compounds that activate lipoxygenase to produce these beneficial mediators.

Development of a method for evaluating the mRNA transcription activity of influenza virus RNA-dependent RNA polymerase through real-time reverse transcription polymerase chain reaction.

BACKGROUND: The development of an influenza RNA-dependent RNA polymerase (RdRp) inhibitor is required; therefore, a method for evaluating the activity of influenza RdRp needs to be developed. The current method uses an ultracentrifuge to separate viral particles and quantifies RdRp activity with radioisotope-labeled nucleosides, such as 32P-GTP. This method requires special equipment and radioisotope management, so it cannot be implemented in all institutions. We have developed a method to evaluate the mRNA transcription activity of RdRp without using ultracentrifugation and radioisotopes. RESULTS: RdRp was extracted from viral particles that were purified from the culture supernatant using anionic polymer-coated magnetic beads that can concentrate influenza virus particles from the culture supernatant in approximately 30 min. A strand-specific real-time reverse transcription polymerase chain reaction (RT-PCR) method was developed based on reverse transcription using tagged primers. RT primers were designed to bind to a sequence near the 3' end of mRNA containing a poly A tail for specific recognition of the mRNA, with an 18-nucleotide tag attached to the 5' end of the sequence. The RT reaction was performed with this tagged RT primer, and the amount of mRNA was analyzed using real-time qPCR. Real-time qPCR using the tag sequence as the forward primer and a segment-specific reverse primer ensured the specificity for quantifying the mRNA of segments 1, 4, and 5. The temperature, reaction time, and Mg2+ concentration were determined to select the optimum conditions for in vitro RNA synthesis by RdRp, and the amount of synthesized mRNAs of segments 1, 4, and 5 was determined with a detection sensitivity of 10 copies/reaction. In addition, mRNA synthesis was inhibited by ribavirin triphosphate, an RdRp inhibitor, thus indicating the usefulness of this evaluation method for screening RdRp inhibitors. CONCLUSION: This method makes it possible to analyze the RdRp activity even in a laboratory where ultracentrifugation and radioisotopes cannot be used. This novel method for measuring influenza virus polymerase activity will further promote research to identify compounds that inhibit viral mRNA transcription activity of RdRp.

Induction of a 5-lipoxygenase product by daidzein is involved in the regulation of influenza virus replication.

This study was conducted to evaluate the regulation mechanism of influenza virus replication following treatment of Madin-Darby canine kidney cells with the soy isoflavone daidzein. We performed comparative qualitative and quantitative analyses of lipid peroxide between mock-infected and virus-infected cells treated with or without daidzein, as it had been reported that daidzein was an antioxidant and lipid peroxide levels increased upon virus infection. Contrary to our belief, lipid peroxides were not elevated in virus-infected cells and no decrease in lipid peroxides was observed in daidzein-treated cells. In daidzein-treated cells, 5-hydroxyeicosatetraenoic acid, the 5-lipoxygenase product derived from arachidonate, was significantly elevated compared to other lipid peroxides. Zileuton (5-lipoxygenase inhibitor) and 5-lipoxygenase knockdown reduced the daidzein-induced antiviral effect. Moreover, virus replication was regulated by treatment with 5-hydroperoxyeicosatetraenoic acid, a precursor of 5-hydroxyeicosatetraenoic acid and 5-lipoxygenase primary product. These results suggest that daidzein regulates virus replication via signal transduction through 5-lipoxygenase products.

Anti-Influenza Virus Activity of Adlay Tea Components.

Our previous study showed anti-influenza virus activity in adlay tea prepared from adlay seeds, naked barley seeds, soybean, and cassia seeds. In this study, we evaluated the anti-influenza virus activity of each component of this tea and analyzed their active ingredients. Each component was roasted and extracted in hot water; the extracts were tested for antiviral activity and their mechanisms of action were studied. All the tea components showed antiviral activity against the H1N1 and H3N2 influenza subtypes and against influenza B. The viral stages inhibited by the components were virus adsorption and replication in proliferative process, suggesting that the action mechanisms of the components might differ from those of oseltamivir acid. Of the tea components, soybean showed the strongest activity. Therefore, we analyzed its active ingredients by liquid chromatography quadruple time-of-flight mass spectrometry (LC/qTOF-MS) and daidzein and glycitein were detected as active ingredients. Here, anti-influenza virus action of glycitein was the first report.

Analysis of the glycoproteins of Seoul orthohantavirus strain B1 associated with fusion activity.

We analyzed two virus variants (S1 and L1) from Seoul orthohantavirus strain B1. Strain B1 produces large opaque plaques when plated on Vero E6 cell monolayers. However, although the L1 variant produced the large opaque plaques common to the strain, the variant S1 produced small clear ones on Vero E6 cells. Five days after Vero E6 cells were infected with the S1 variant, polykaryons formed spontaneously. However, the cells infected with the L1 variant did not show the formation of syncytia. An analysis of the pH dependency of the cell fusion demonstrated that the L1 variant could induce cell fusion, but only at a pH that was 0.2 units lower than the pH at which the S1 variant induced it. Sequencing of the M genome segment of the two virus variants revealed amino acid substitutions at 4 positions in the Gn and Gc gene products of the S1 variant. Two of these substitutions occurred in the extracellular domain of Gn and changed the charge of the protein. Our findings suggest that these amino acid substitutions caused the S1 variant Gn protein to induce fusion at an elevated pH.

Inhibition of influenza virus replication by adlay tea.

BACKGROUND: The present study was conducted aiming to examine the antiviral activity of adlay tea and its components against influenza viruses. We further aimed to clarify the mechanism by which these components regulate virus replication. RESULTS: Adlay tea at a concentration suitable for drinking inhibited the multiplication of influenza viruses. Moreover, our results suggest that individual components of the tea had antiviral activities against the influenza A/PR/8/34 virus. Adlay tea inhibited multiplication of the H1N1, H3N2 and B types of influenza virus, including oseltamivir-resistant viruses. In addition, adlay tea inhibited influenza infection during the periods of virus adsorption to the cell and virus replication. Adlay tea did not suppress hemagglutination inhibition or cell fusion, although it slightly inhibited virus binding to Malin Darby canine kidney cells. Furthermore, our findings suggest that the antiviral compounds included in adlay tea were ingredients other than polyphenols and that there were several types of effective compounds in adlay tea inhibiting several steps of viral replication. CONCLUSION: The results of the present study demonstrate that adlay tea had antiviral effects against influenza viruses. Our findings with respect to adlay tea suggest that the polyphenols might have a small influence on its antiviral activity and that other ingredients might have more influence. © 2017 Society of Chemical Industry.

Appearance of renal hemorrhage in adult mice after inoculation of patient-derived hantavirus.

BACKGROUND: Hemorrhagic fever with renal syndrome (HFRS) caused by hantavirus infection is characterized by fever, renal dysfunction and hemorrhage. An animal model mimicking symptoms of HFRS remains to be established. In this study, we evaluated the pathogenicity of an HFRS patient-derived Hantaan virus (HTNV) in adult mice. METHODS: Five clones of HTNV strain KHF 83-61 BL (KHFV) that was derived from blood of an HFRS patient were obtained by plaque cloning. The pathogenicity of the virus clones was evaluated by using 6-week-old female BALB/c mice. Sequence analysis of the viral genome was performed by conventional methods. RESULTS: All of the mice intravenously inoculated with KHFV clone (cl)-1, -2, -3 and -5 showed signs of disease such as transient body weight loss, ruffled fur, reduced activity and remarkably prominent hemorrhage in the renal medulla at 6 to 9 days post-inoculation (dpi) and then recovered. In contrast, mice intravenously inoculated with KHFV cl-4 did not show any signs of disease. We selected KHFV cl-5 and cl-4 as representative of high-pathogenic and low-pathogenic clones, respectively. Quantities of viral RNA in kidneys of KHFV cl-5-infected mice were larger than those in KHFV cl-4-infected mice at any time point examined (3, 6, 9 and 12 dpi). The quantities of viral RNA of KHFV cl-5 and cl-4 peaked at 3 dpi, which was before the onset of disease. Sequence analysis revealed that the amino acid at position 417 in the glycoprotein Gn was the sole difference in viral proteins between KHFV cl-5 and cl-4. The result suggests that amino acid at position 417 in Gn is related to the difference in pathogenicity between KHFV cl-5 and cl-4. When the inoculum of KHFV cl-5 was pretreated with a neutralizing antibody against HTNV strain 76-118, which belongs to the same serotype as KHFV clones, mice did not show any signs of disease, confirming that the disease was caused by KHFV infection. CONCLUSION: We found that an HFRS patient-derived HTNV caused renal hemorrhage in adult mice. We anticipate that this infection model will be a valuable tool for understanding the pathogenesis of HFRS.

Analysis of ganciclovir-resistant human herpesvirus 6B clinical isolates using quenching probe PCR methodology.

Quenching probe PCR (QP-PCR) analysis was used to determine the frequency of ganciclovir (GCV) resistance among clinical isolates of human herpesvirus 6B (HHV-6B) obtained from patients with primary viral infection and viral reactivation. Forty-two HHV-6B clinical isolates were repeatedly recovered from 15 hematopoietic stem cell transplant (HSCT) recipients, and 20 isolates were recovered from 20 exanthem subitum (ES) patients. Of the 15 HSCT recipients, 9 received GCV during the observation period; however, none of the ES patients were treated with GCV. Two established laboratory strains, Z29 and HST, were used as standards in this study. Regions 1 and 2 of the U69 gene of all of the clinical isolates demonstrated the same melting temperature as regions 1 and 2 of the Z29 strain. For region 3, the melting temperatures of all clinical isolates fell between the melting temperature of the plasmid containing the A462D single nucleotide polymorphism (SNP) and the melting temperature of the Z29 strain, and the melting temperatures profiles of all clinical isolates were similar to the melting temperature profile of the Japanese HST strain. As expected, none of the 20 clinical isolates recovered from the ES patients and the 14 isolates recovered from the HSCT recipients who did not receive GCV treatment carried the six known SNPs associated with GCV resistance. Interestingly, these six SNPs were not detected in the 28 clinical isolates recovered from the 9 HSCT recipients who received GCV. Additional sequence analysis of the U69 gene from the 15 representative isolates from the 15 HSCT recipients identified other SNPs. These SNPs were identical to those identified in the HST strain. Therefore, the rate of emergence of GCV-resistant HHV-6B strains appears to be relatively low, even in HSCT recipients treated with GCV.

Activation of Immune and Antiviral Effects by Euglena Extracts: A Review.

Influenza is an acute respiratory illness caused by influenza virus infection, which is managed using vaccines and antiviral drugs. Recently, the antiviral effects of plants and foods have gained attention. Euglena is a motile unicellular alga and eukaryotic photosynthetic microorganism. It has secondary chloroplasts and is a mixotroph able to feed by photosynthesis or phagocytosis. This review summarizes the influenza treatment effects of Euglena from the perspective of a functional food that is attracting attention. While it has been reported that Euglena contributes to suppressing blood sugar levels and ameliorates symptoms caused by stress by acting on the autonomic nervous system, the immunostimulatory and antiviral activities of Euglena have also been reported. In this review, I focused on the immunostimulation of antiviral activity via the intestinal environment and the suppression of viral replication in infected cells. The functions of specific components of Euglena, which also serves as the source of a wide range of nutrients such as vitamins, minerals, amino acids, unsaturated fatty acids, and ß-1,3-glucan (paramylon), are also reviewed. Euglena has animal and plant properties and natural compounds with a wide range of functions, providing crucial information for improved antiviral strategies.

Anti-Influenza Virus Activity of Citrullus lanatus var. citroides as a Functional Food: A Review.

Influenza is an acute respiratory illness caused by the influenza virus, in response to which vaccines and antiviral drugs are administered. In recent years, the antiviral effects of plants and foods have garnered attention. This review is the first to summarize the therapeutic properties of wild watermelon (Citrullus lanatus var. citroides) against influenza from a phytochemical viewpoint. Wild watermelon is a wild plant with significant potential as a therapeutic candidate in antiviral strategies, when focused on its multiple anti-influenza functionalities. Wild watermelon juice inhibits viral growth, entry, and replication. Hence, we highlight the possibility of utilizing wild watermelon for the prevention and treatment of influenza with stronger antiviral activity. Phytochemicals and phytoestrogen (polyphenol, flavonoids, and prenylated compounds) in wild watermelon juice contribute to this activity and inhibit various stages of viral replication, depending on the molecular structure. Wild plants and foods closely related to the original species contain many natural compounds such as phytochemicals, and exhibit various viral growth inhibitory effects. These natural products provide useful information for future antiviral strategies.

Daidzein phosphorylates and activates 5-lipoxygenase via the MEK/ERK pathway: a mechanism for inducing the production of 5-lipoxygenase metabolite that inhibit influenza virus intracellular replication.

We previously reported that the soy isoflavone daidzein (Dz) suppresses the intracellular replication of influenza virus and that arachidonic acid-derived oxidation product via lipid oxidase 5-lipoxygenase (5-LOX) is involved in its antiviral effect. The activation of 5-LOX by Dz triggers anti-influenza activity; however, the mechanism of activation of 5-LOX remains unclear. Therefore, in this study, we aimed to clarify the activation mechanism using human monocyte-derived THP-1 cells differentiated using phorbol 12-myristate 13-acetate. THP-1 cells expressed 5-LOX endogenously and Dz did not induce 5-LOX expression. However, 8 h after treatment with Dz, the amount of 5-hydroxyeicosatetraenoic acid (5-HETE), an arachidonic acid oxidation product via 5-LOX, increased significantly suggesting that the enzyme is activated regardless of changes in 5-LOX protein levels. Intracellular Ca2+ content, ATP concentration, 5-LOX protein phosphorylation, and 5-LOX intracellular localization are known 5-LOX activation factors. The intracellular Ca2+ and ATP concentrations were not affected by Dz treatment. The enzymatic activity of 5-LOX is regulated by the phosphorylation of three serine residues and four tyrosine residues. Pretreatment with inhibitors of each kinase revealed that Dz-induced 5-HETE production was suppressed by the MEK/ERK inhibitor. 5-LOX in which the Ser663 residue was phosphorylated was found to be increased in the nuclear fraction of Dz-treated THP-1 cells. Furthermore, immunocytochemistry showed that 5-LOX translocates to the nuclear envelope following Dz treatment. These results indicate that Dz activates 5-LOX by phosphorylating Ser663 via the MEK/ERK pathway. Thus, these results demonstrate that Dz exerts anti-influenza virus activity via the MEK/ERK signal transduction pathway.

Mode of Antifungal Action of Daito-Gettou (Alpinia zerumbet var. exelsa) Essential Oil against Aspergillus brasiliensis.

Plant-derived essential oils (EOs) are used in medicines, disinfectants, and aromatherapy products. Information on the antifungal activity of EO of Alpinia zerumbet var. exelsa (known as Daito-gettou) found in Kitadaito Island, Okinawa, is limited. Therefore, we aimed to evaluate the antifungal activity of EOs obtained via steam distillation of leaves of Daito-gettou, which is a hybrid of A. zerumbet and A. uraiensis. Daito-gettou EO showed antifungal activity (minimum inhibitory concentration = 0.4%) against Aspergillus brasiliensis NBRC 9455, which was comparable to that of A. zerumbet found in the Okinawa main island. Gas chromatography/mass spectrometry revealed that the main components of Daito-gettou EOs are γ-terpinene, terpinen-4-ol, 1,8-cineole, 3-carene, and p-cymene. Terpinen-4-ol content (MIC = 0.075%) was 17.24%, suggesting that the antifungal activity of Daito-gettou EO was mainly attributable to this component. Daito-gettou EO and terpinen-4-ol inhibited mycelial growth. Moreover, calorimetric observations of fungal growth in the presence of Daito-gettou EO showed a characteristic pattern with no change in the initial growth rate and only a delay in growth. As this pattern is similar to that of amphotericin B, it implies that the action mode of Daito-gettou EO and terpinen-4-ol may be fungicidal. Further studies on the molecular mechanisms of action are needed for validation.

Anti-influenza A virus activity of flavonoids in vitro: a structure-activity relationship.

Secondary plant metabolites from food extracts, namely daidzein, quercetin, and luteolin, exhibit anti-influenza virus effects, with IC50 values of 143.6, 274.8, and 8.0 µM, respectively. The activities of these metabolites differ depending on the functional groups. Therefore, in this study, we focused on members of the flavonoid group, and investigated the anti-influenza viral effects of different flavonoid classes (flavone, isoflavone, flavonol, flavanone, and flavan-3-ol) in vitro. The IC50 values were 4.9-82.8 µM, 143.6 µM, 62.9-477.8 µM, 290.4-881.1 µM, and 22.9-6717.2 µM, respectively, confirming their activity. The modifying group factors (number, position, type) in the flavonoid skeleton may be significantly related to the anti-influenza virus activity. Moreover, time-of-addition assay revealed that the mechanism of inhibition varied for the different classes; for example, flavonoids that inhibit virus adsorption or the early stage of viral growth. Interestingly, all the examined flavonoids inhibited the late stages of viral growth, suggesting that flavonoids mainly inhibit the late events in viral growth before the release of viral particles. Additionally, apigenin might be effective against oseltamivir-resistant strains. Our results may be important in the development of anti-influenza virus therapeutic strategies in the future.

Inhibition of influenza virus replication by Apiaceae plants, with special reference to Peucedanum japonicum (Sacna) constituents.

ETHNOPHARMACOLOGICAL RELEVANCE: Apiaceae plants possess various pharmacological properties, such as antimicrobial, antioxidant, hypoglycemic, hypolipidemic, anxiolytic, analgesic, anti-inflammatory, anti-convulsant, and anti-cancer activities; however, data on their antiviral activity are limited. Peucedanum japonicum, also known as Sacna, is a plant used as food and as a traditional folk medicine for treating coughs. However, the active components in the leaves of this plant are yet unexplored. AIM OF THE STUDY: To assess Apiaceae plants, especially Peucedanum japonicum, with anti-viral activity, and the function and antiviral potential of Sacna constituents, considering the emergence of influenza virus strains resistant to the currently available drugs. MATERIALS AND METHODS: We prepared grinds of the freeze-dried leaves and roots of the Apiaceae family and the hot water extracts. The antiviral activities of the extracts were determined by focus formation reduction assay. In the time-of-addition assay, the test medium containing Sacna extract at 2 mg/mL was added at -1 to 0 h (adsorption) or from 0 to 4, 4 to 8, or 0 to 8 h (replication). The Sacna extract was separated by reversed-phase flash column chromatography using an Isolera Spektra system. The antiviral activity of each fraction was then determined using the focus formation reduction assay. The active fraction was analyzed using an LC20ADXR high performance liquid chromatography system equipped with a microTOF-QII quadrupole time-of-flight tandem mass spectrometer. RESULTS: All examined extracts of Apiaceae plants showed anti-influenza activity. Sacna extract most strongly inhibited the replication of influenza viruses. Individual components of Sacna possess antiviral activities against the influenza A/PR/8/34 virus. Sacna was found to inhibit the multiplication of A (H1N1 and H3N2) types and B types of influenza viruses, including amantadine-resistant and oseltamivir-resistant viruses. Sacna also inhibited influenza infection during viral replication. However, Sacna did not inhibit influenza infection during cell adsorption and did not suppress hemagglutination inhibition or cell fusion. Further, our findings suggest that the antiviral compounds in Sacna include flavonoids (quercetin and luteolin) and other polyphenols (caffeic acid, hymecromone, and umbelliferone). Although several effective compounds in Sacna inhibit multiple steps of viral replication, caffeic acid, which was increased by heat treatment at the time of extraction, significantly inhibited only the late period of viral growth, similar to the Sacna extract, indicating that it is the major component responsible for the antiviral activity of Sacna. CONCLUSIONS: Apiaceae plants possess antiviral activity. Caffeic acid is the major component responsible for the antiviral activity of Sacna. To our knowledge, this is the first report regarding the anti-influenza virus activity of Sacna. Overall, these results indicate that Sacna has potential as a novel treatment against influenza A and B viruses.

Effect of Structural Differences in Naringenin, Prenylated Naringenin, and Their Derivatives on the Anti-Influenza Virus Activity and Cellular Uptake of Their Flavanones.

Vaccines and antiviral drugs are widely used to treat influenza infection. However, they cannot rapidly respond to drug-resistant viruses. Therefore, new anti-influenza virus strategies are required. Naringenin is a flavonoid with potential for new antiviral strategies. In this study, we evaluated the antiviral effects of naringenin derivatives and examined the relationship between their cellular uptake and antiviral effects. Madin-Darby canine kidney (MDCK) cells were infected with the A/PR/8/34 strain and exposed to the compound-containing medium for 24 h. The amount of virus in the supernatant was calculated using focus-forming reduction assay. Antiviral activity was evaluated using IC50 and CC50 values. Cells were exposed to a constant concentration of naringenin or prenylated naringenin, and intracellular uptake and distribution were evaluated using a fluorescence microscope. Prenylated naringenin showed strong anti-influenza virus effects, and the amount of intracellular uptake was revealed by the strong intracellular fluorescence. In addition, intracellular distribution differed depending on the position of the prenyl group. The steric factor of naringenin is deeply involved in influenza A virus activity, and prenyl groups are desirable. Furthermore, the prenyl group affects cellular affinity, and the uptake mechanism differs depending on its position. These results provide important information on antiviral strategies.

Influenza virus entry and replication inhibited by 8-prenylnaringenin from Citrullus lanatus var. citroides (wild watermelon).

We previously demonstrated the anti-influenza activity of Citrullus lanatus var. citroides (wild watermelon, WWM); however, the active ingredient was unknown. Here, we performed metabolomic analysis to evaluate the ingredients of WWM associated with antiviral activity. Many low-molecular weight compounds were identified, with flavonoids accounting for 35% of all the compounds in WWM juice. Prenylated flavonoids accounted for 30% of the flavonoids. Among the measurable components of phytoestrogens in WWM juice, 8-prenylnaringenin showed the highest antiviral activity. We synthesized 8-prenylnaringenin and used liquid chromatography-mass spectrometry to quantitate the active ingredient in WWM. The antiviral activities of 8-prenylnaringenin were observed against H1N1 and H3N2 influenza A subtypes and influenza B viruses. Moreover, 8-prenylnaringenin was found to inhibit virus adsorption and late-stage virus replication, suggesting that the mechanisms of action of 8-prenylnaringenin may differ from those of amantadine and oseltamivir. We confirmed that 8-prenylnaringenin strongly inhibited the viral entry of all the influenza virus strains that were examined, including those resistant to the anti-influenza drugs oseltamivir and amantadine. This result indicates that 8-prenylnaringenin may activate the host cell's defense mechanisms, rather than directly acting on the influenza virus. Since 8-prenylnaringenin did not inhibit late-stage virus replication of oseltamivir-resistant strains, 8-prenylnaringenin may interact directly with viral neuraminidase. These results are the first report on the anti-influenza virus activity of 8-prenylnaringenin. Our results highlight the potential of WWM and phytoestrogens to develop effective prophylactic and therapeutic approaches to the influenza virus.

Antiviral Activity and Underlying Action Mechanism of Euglena Extract against Influenza Virus.

It is difficult to match annual vaccines against the exact influenza strain that is spreading in any given flu season. Owing to the emergence of drug-resistant viral strains, new approaches for treating influenza are needed. Euglena gracilis (hereinafter Euglena), microalga, used as functional foods and supplements, have been shown to alleviate symptoms of influenza virus infection in mice. However, the mechanism underlying the inhibitory action of microalgae against the influenza virus is unknown. Here, we aimed to study the antiviral activity of Euglena extract against the influenza virus and the underlying action mechanism using Madin-Darby canine kidney (MDCK) cells. Euglena extract strongly inhibited infection by all influenza virus strains examined, including those resistant to the anti-influenza drugs oseltamivir and amantadine. A time-of-addition assay revealed that Euglena extract did not affect the cycle of virus replication, and cell pretreatment or prolonged treatment of infected cells reduced the virus titer. Thus, Euglena extract may activate the host cell defense mechanisms, rather than directly acting on the influenza virus. Moreover, various minerals, mainly zinc, in Euglena extract were found to be involved in the antiviral activity of the extract. In conclusion, Euglena extract could be a potent agent for preventing and treating influenza.

Juice of Citrullus lanatus var. citroides (wild watermelon) inhibits the entry and propagation of influenza viruses in vitro and in vivo.

Vaccines and various anti-influenza drugs are clinically used to prevent and treat influenza infections. However, with the antigenic mismatch of vaccines and the emergence of drug-resistant viral strains, new approaches for treating influenza are warranted. This study focused on natural foods as potential candidates for the development of new treatment options for influenza infections. The screening of plants from the Cucurbitaceae family revealed that the juice of Citrullus lanatus var. citroides (wild watermelon) had the strongest ability to inhibit the replication of influenza virus in Madin-Darby canine kidney cells. The results of a time-of-addition assay indicated that wild watermelon juice (WWMJ) inhibits the adsorption and late stages of viral replication, suggesting that WWMJ contains multiple constituents with effective anti-influenza activity. A viral adsorption analysis showed that WWMJ reduces the amount of viral RNA in the cells at 37°C but not at 4°C, confirming that WWMJ inhibits viral entry into the host cells at 37°C. These results suggest that a mechanism other than the inhibition of viral attachment is involved in the anti-influenza action of WWMJ, which is perhaps responsible for a reduction in internalization of the virus. Administration of WWMJ into the nasal mucosa of BALB/c mice infected with the A/PR/8/34 mouse-adapted influenza virus was seen to significantly improve the survival rate. The findings of this study, therefore, demonstrate the anti-influenza potential of WWMJ in vitro and in vivo, thereby suggesting the candidature of WWMJ as a functional food product that can be used to develop anti-influenza agents and drugs.

PCR with quenching probes enables the rapid detection and identification of ganciclovir-resistance-causing U69 gene mutations in human herpesvirus 6.

A single-nucleotide polymorphism detection assay using PCR with quenching probes (QP-PCR) was developed for the rapid detection of antiviral drug-resistance mutations of human herpesvirus 6 (HHV-6). The mutations examined were in the HHV-6 U69 gene, and were single-base mutations in sequences known to be associated with ganciclovir (GCV) resistance in HCMV. We previously confirmed that they conferred GCV resistance to recombinant baculoviruses (Nakano et al., J. Virol. Methods 161:223-230, 2009). Six characterized mutations, including a previously reported one that encodes a GCV-sensitive kinase-activity mutant (Isegawa et al., J. Clin. Virol. 44:15-19, 2009), were used. The six mutations were separated into three groups based on their location in the U69 protein, and detected by the hybridization of three probes. We developed and validated a set of assays for these mutations using PCR followed by differential melting of a fluorescently labeled oligo probe, on a Roche Light Cycler platform. Nucleobase quenching was used to detect the hybridized probe. The optimized assay could distinguish the different mutants, and easily detected mutants representing 30% of the DNA in a mixed sample. This QP-PCR assay permitted the rapid (1.5 h), objective, and reproducible detection of drug-resistant mutations of HHV-6.

The U95 protein of human herpesvirus 6B interacts with human GRIM-19: silencing of U95 expression reduces viral load and abrogates loss of mitochondrial membrane potential.

To better understand the pathogenesis of human herpesvirus 6 (HHV-6), it is important to elucidate the functional aspects of immediate-early (IE) genes at the initial phase of the infection. To study the functional role of the HHV-6B IE gene encoding U95, we generated a U95-Myc fusion protein and screened a pretransformed bone marrow cDNA library for U95-interacting proteins, using yeast-two hybrid analysis. The most frequently appearing U95-interacting protein identified was GRIM-19, which belongs to the family of genes associated with retinoid-interferon mortality and serves as an essential component of the oxidative phosphorylation system. This interaction was verified by both coimmunoprecipitation and confocal microscopic coimmunolocalization. Short-term HHV-6B infection of MT-4 T-lymphocytic cells induced syncytial formation, resulted in decreased mitochondrial membrane potential, and led to progressively pronounced ultrastructural changes, such as mitochondrial swelling, myelin-like figures, and a loss of cristae. Compared to controls, RNA interference against U95 effectively reduced the U95 mRNA copy number and abrogated the loss of mitochondrial membrane potential. Our results indicate that the high affinity between U95 early viral protein and GRIM-19 may be closely linked to the detrimental effect of HHV-6B infection on mitochondria. These findings may explain the alternative cell death mechanism of expiration, as opposed to apoptosis, observed in certain productively HHV-6B-infected cells. The interaction between U95 and GRIM-19 is thus functionally and metabolically significant in HHV-6B-infected cells and may be a means through which HHV-6B modulates cell death signals by interferon and retinoic acid.