Activity of the Keggin polyoxotungstate PM-19 against herpes simplex virus type 2 infection in immunosuppressed mice: role of peritoneal macrophage activation

New synergistic antibacterial mechanism of bulky mixed Ti/w hetero-polyoxometalates composed of multi lacunary Keggin structure with oxacillin against vancomycin intermediate-resistant Staphylococcus aureus

Considering the lack of detailed research on the antibacterial mechanism of polyoxometalates, we examined the synergistic effect of novel bulky mixed Ti/W hetero-polyoxometalates (K9.5H2.5 ［α-Ge2Ti4W20O78］・ 29H2O; αTi4, K9H5 ［α-Ge2Ti6W18O77］・16H2O; αTi6, K23H5［α-Ge4Ti12W36O154］・39H2O; αTi12, K9H5 ［β-Ge2Ti6W18O77］・ 45H2O; βTi6) with the antibiotic oxacillin against vancomycin intermediate-resistant Staphylococcus aureus (VISA) using fractional inhibitory concentration (FIC) index and growth curve in this study. All polyoxometalates used in this study showed remarkable synergistic effects with oxacillin. Its synergistic antibacterial mechanism was examined using reverse transcription PCR (RT-PCR) and penicillin binding protein-2' (PBP2') latex agglutination test. The results suggested that these polyoxometalates did not inhibit mecA gene transcription but resulted in PBP2' protein malfunction. From these results, we concluded that the substances producing resistance in VISA were affected by polyoxometalates depending on their molecular size, facilitating a synergistic antibacterial effect with oxacillin.

Promising application of polyoxometalates in the treatment of cancer, infectious diseases and Alzheimer's disease

As shown in studies conducted in recent decades, polyoxometalates (POMs), as inorganic metal oxides, have promising biological activities, including antitumor, anti-infectious and anti-Alzheimer’s activities, due to their special structures and properties. However, some side effects impede their clinical applications to a certain extent. Compared with unmodified POMs, POM-based inorganic–organic hybrids and POM-based nanocomposite structures show significantly enhanced bioactivity and reduced side effects. In this review, we introduce the biological activities of POMs and their derivatives and highlight the side effects of POMs on normal cells and organisms and their possible mechanisms of action. We then propose a development direction for overcoming their side effects. POMs are expected to constitute a new generation of inorganic metal drugs for the treatment of cancer, infectious diseases, and Alzheimer's disease.

Graphical abstract

In vitro Antimicrobial Effects of Virus Block, Which Contains Multiple Polyoxometalate Compounds, and Hygienic Effects of Virus Block-Supplemented Moist Hand Towels

BACKGROUND

Historical evidence has verified the multifaceted antiviral efficacy of polyoxometalates (PMs).

METHODS

We carried out a study to investigate the antimicrobial effects of each of the 5 substances comprising virus block (VB): 3 PMs that have antibacterial and antiviral activity, an antibiotic agent, and an antibacterial agent. We also investigated the effectiveness of the addition of VB to moist hand towels in a study involving 120 volunteers. The time-dependent changes in metal ion concentrations in aqueous VB solution were analyzed using inductively coupled plasma atomic emission spectroscopy.

RESULTS

The metal elements in the aqueous VB solution remained stable for 12 weeks without undergoing time-dependent changes.

DISCUSSION

Further investigations were performed to study hand hygiene using moist hand towels in daily life settings. To this end, 120 volunteers provided 240 specimens that were used to investigate the presence of antibacterial compounds on the volunteers' hands before and after hand towel use. An aliquot of each specimen was suspended in phosphate-buffered saline and plated on agar media, and the number of colonies formed was counted. Normal bacterial flora found on the hands of the volunteers was investigated before and after the use of 4 different moist hand towels.

CONCLUSIONS

The effects of VB and PMs were superior to those of commercial moist hand towels, indicating that effective data were obtained that may be useful for the practical application of the tested items.

Toxicity evaluation of two polyoxotungstates with anti-acetylcholinesterase activity

A toxicity evaluation of two Keggin-type heteropolytungstates, K₇[Ti₂PW₁₀O₄₀]·6H₂O and K₆H[SiV₃W₉O₄₀]·3H₂O, with different inhibitory potencies toward acetylcholinesterase activity (IC₅₀ values of 1.04×10^-6 and 4.80×10^-4mol/L, respectively) was performed. Wistar albino rats were orally treated with single doses (5 and 50mg/kg) of both investigated compounds. The biochemical parameters of renal (serum urea and creatinine) and liver function (direct and total bilirubin, alanine transaminase, and aspartate aminotransferase) were determined after 24h and 14days. A histopathological analysis of liver tissue was carried out 14days after the polyoxotungstate administration. Both applied doses of the investigated compounds did not induce statistically significant alterations of the renal function markers. However, the polyoxotungstate treatment caused an increase in the activities of serum alanine transaminase and aspartate aminotransferase in a time- and concentration-dependent manner, although statistically significant changes in bilirubin concentrations were not observed. Furthermore, the detected hepatotoxic effect was confirmed by histhopathological analysis that suggested some reversible liver tissue damage two weeks after the treatment, especially in the case of K₆H[SiV₃W₉O₄₀]·3H₂O. Accordingly, the toxicity of these two polyoxotungstates with anti-acetylcholinesterase effect cannot be considered as a severe one, but their potential clinical application would require a more complex toxicological study.

A Novel Application of Ti-Substituted Polyoxometalates: Anti-Inflammatory Activity in OVA-Induced Asthma Murine Model

Objective. Asthma is a chronic inflammatory disorder. Despite extensive researches into the treatment and management of it, current treatments and management strategies are still limited. The search for a novel approach to its treatments is urgently needed. Researches on the potential medical use of polyoxometalates (POMs) have already shown it has antiviral and antitumor bioactivities. But the effects of POM in immune systems are still largely unknown. Methods. In order to investigate the role of POM in the asthmatic disease, we used OVA-induced asthma murine model and observed the pathological changes between mice that received three different Ti-substituted POMs (0.3 μg per mouse per dose) when challenged with OVA. We also measured the type 2 cytokine expressions to reveal the potential mechanism. Results and Conclusions. Our results showed that two Ti-substituted POMs, K₅H₂[FeW₁₁TiO₄₀]·17H₂O and K₅H[H₂ZnW₁₁TiO₄₀]·35H₂O, could reduce OVA-induced lung inflammation, serum IgE level (around 2000 ng/mL to less than 1000 ng/mL), leukocytes infiltration in the lung, and cytokines levels (including IL-4, IL-5, IL-13, and TNF-α) but Ti-centered POM K₄[TiW₁₂O₄₀]·10H₂O did not. Thus, Ti-substituted POMs may have pharmaceutical values especially in treatments for asthmatic diseases.

In-vitro anti Myxovirus Activity and Mechanism of Antiinfluenzavirus Activity of Polyoxometalates PM-504 and PM-523

Sixty polyoxometalates were examined for anti-influenza A virus (FluV-A) activity in vitro. Two of the most potent and least cytotoxic compounds, PM-504 K9H5(Ge2Ti6W18O77)16H2O] and PM-523 (iPrNH3)6H [PTi2W10O38(O2)9H2O2] were selected for further studies. Examination of the antiviral effects of PM-504 and PM-523 against other human ortho- and paramyxoviruses revealed that both compounds had broad spectrum antimyxovirus activities. From a time of addition study and FACS analysis for influenza A virus infected cells, the compounds were found not to inhibit binding of virus to MDCK cells. However, these compounds inhibited haemolysis of chicken erythrocytes by virus and also inhibited fluorescence dequenching of octadecylrhodamine B-labelled virus after binding to cells. This indicates that these polyoxometalates inhibited fusion of the virus envelope to the cellular membrane.

Broad-spectrum antiviral property of polyoxometalate localized on a cell surface

Cs2K4Na[SiW9Nb3O40] has broad antiviral ability including anti-Influenza A, -Influenza B, -HSV-1, -HSV-2, -HIV-1, and -HBV. A series of antivirus and/or biochemical experiments and X-ray nanotomography analysis confirm that this kind of broad-spectrum antiviral property is mainly due to its localization on the cell surface.

Pharmacokinetics of anti-HBV polyoxometalate in rats

Polyoxometalates are non-nucleoside analogs that have been proven to exhibit broad-spectrum antiviral activity. In particular, Cs₂K₄Na[SiW₉Nb₃O₄₀].H₂O 1 shows low toxicity and high activity against HBV. The preclinical pharmacokinetics of Compound 1 in rats were characterized by establishing and applying inductively coupled plasma-mass spectrometry method to determine the concentration of W in plasma, urine, feces, bile and organ samples. The quantitative ICP-MS method demonstrated good sensitivity and application in the pharmacokinetics study of polyoxometalates. The pharmacokinetic behavior of Compound 1 after intravenous or oral administration fit a two-compartment model. T_max ranges from 0.1 h to 3 h and the T_1/2 of Compound 1 is between 20 h and 30 h. The absolute bioavailability of Compound 1 at 45, 180 and 720 mg/kg groups were 23.68%, 14.67% and 11.93%, respectively. The rates of plasma protein binding of Compound 1 at 9, 18 and 36 mg/ml of Compound 1 are 62.13±9.41%, 71.20±24.98% and 49.00±25.59%, respectively. Compound 1 was widely distributed throughout the body, and high levels of compound 1 were found in the kidney and liver. The level of Compound 1 in excretion was lower: 30% for urine, 0.28% for feces and 0.42% for bile, respectively. For elaborate pharmacokinetic characteristics to be fully understood, the metabolism of Compound 1 needs to be studied further.

Polyoxometalates active against tumors, viruses, and bacteria

Polyoxometalates (PMs) as discrete metal-oxide cluster anions with high solubility in water and photochemically and electrochemically active property have a wide variety of structures not only in molecular size from sub-nano to sub-micrometers with a various combination of metals but also in symmetry and highly negative charge. One of the reasons for such a structural variety originates from their conformation change (due to the condensed aggregation and the structural assembly) which strongly depends on environmental parameters such as solution pH, concentration, and coexistent foreign inorganic and/or organic substances. In the course of the application of the physicochemical properties of such PMs to the medical fields, antitumoral, antiviral, and antibacterial activities have been developed for realization of a novel inorganic medicine which provides a biologically excellent activity never replaced by other approved medicines. Several PMs as a candidate for clinical uses have been licensed toward the chemotherapy of solid tumors (such as human gastric cancer and pancreatic cancer), DNA and RNA viruses (such as HSV, HIV, influenza, and SARS), and drug-resistant bacteria (such as MRSA and VRSA) in recent years: [NH3Pr(i)]6[Mo7O24]∙3H2O (PM-8) and [Me3NH]6[H2Mo(V) 12O28(OH)12(Mo(VI)O3)4]∙2H2O (PM-17) for solid tumors; K7[PTi2W10O40]∙6H2O (PM-19), [Pr(i)NH3]6H[PTi2W10O38(O2)2]∙H2O (PM-523), and K11H[(VO)3(SbW9O33)2]∙27H2O (PM-1002) for viruses; and K6[P2W18O62]∙14H2O (PM-27), K4[SiMo12O40]∙3H2O (SiMo12), and PM-19 for MRSA and VRSA. The results are discussed from a point of view of the chemotherapeutic clarification in this review.

Molecular simulation study of the binding mechanism of [α-PTi2W10O40]7- for its promising broad-spectrum inhibitory activity to FluV-A neuraminidase

Polyoxometalate (POM) has promising antiviral activities. It shows broad-spectrum inhibiting ability, high efficiency, and low toxicity. Experimental assays show that titanium containing polyoxotungstates have anti-influenza-virus activity. In this paper, the binding mechanisms of five isomers of di-Ti-substituted polyoxotungstate, [α-1,2-PTi₂W₁₀O₄₀]^7- (α-1,2), [α-1,6-PTi₂W₁₀O₄₀]^7- (α-1,6), [α-1,5-PTi₂W₁₀O₄₀]^7- (α-1,5), [α-1,4-PTi₂W₁₀O₄₀]^7- (α-1,4) and [α-1,11-PTi₂W₁₀O₄₀]^7- (α-1,11), to five subtypes of influenza virus A neuraminidase (FluV-A NA) were investigated in the context of aqueous solution by using molecular docking and molecular dynamics studies. The results show that the isomer α-1,2 is superior to other isomers as a potential inhibitor to neuraminidase. The positively charged arginine residues around the active site of NA could be induced by negatively charged POM to adapt themselves and could form salt bridge interactions and hydrogen bond interactions with POM. The binding free energies of POM/NA complexes range from -5.36 to -8.31 kcal mol^-1. The electrostatic interactions are found to be the driving force during the binding process of POM to NA. The conformational analysis shows that POM tends to bind primarily with N1 and N8 at the edge of the active pocket, which causes the conformational change of the pincers structure comprising residue 347 and loop 150. Whereas, the active pockets of N2, N9 and N4 are found to be more spacious, which allows POM to enter into the active pockets directly and anchor there firmly. This study shows that negatively charged ligand as POM could induce the reorganization of the active site of NA and highlights POM as a promising inhibitor to NA despite the ever increasing mutants of NA.

Electronic Supplementary Material

Supplementary material is available for this article at 10.1007/s11434-010-3271-8 and is accessible for authorized users.

Antitumor activity of polyoxomolybdate, [NH3Pri]6[Mo7O24].3H2O, against, human gastric cancer model

Polyoxometalates are negatively charged inorganic compounds which contain metal ions such as tungsten, molybdenum, vanadium etc. and which make clusters with the surrounding oxygen atoms. [NH3Pri]6[Mo7O24].3H2O (PM-8) was found to be a significant antitumor polyoxomolybdates. It had already been reported that the PM-8 suppressed the growth of Co-4 human colon cancer, MX-1 human breast cancer and OAT human lung cancer xenografted in nude mice. However, the mechanism of the antitumor activity has not been clarified. In this study, the antitumor activity of one of the metal oxide clusters (polyoxometalates), hexabis(isopropylammonium) heptamolybdate trihydrate, [NH3Pri]6[Mo7O24].3H2O (PM-8) were shown in an MTS assay. DNA ladder formation and detection of apoptotic bodies in nuclei were revealed that antitumor activity of PM-8 in MKN45 cells was due to apoptosis. It is concluded that the observation of significant tumor growth suppression of PM-8 in MKN45-bearing mice results from the induction of apoptosis. PM-8 shows promise as a novel anti-cancer agent.

Anticancer activity of polyoxomolybdate

Anticancer polyoxomolybdates have been investigated for medical application of polyoxometalates as discrete cluster anions of metal oxides. [NH3Pri]6[Mo7O24].3H2O (PM-8) has been recognized as one of significant antitumoral polyoxomolybdates. PM-8 had shown the growth suppression against several tumors, for examples, Co-4, human colon cancer, MX-1, human breast cancer, and OAT, human lung cancer. PM-8 showed the tumor growth suppression for MKN-45 human gastric cancer in tumor bearing mice. PM-8 inhibited the cell growth of AsPC-1 which depended on the dose with showing DNA ladder formation and DNA fragmentation, and positive Hoechst staining indicating apoptosis. The ratio of apoptotic cells on flow cytometry analysis were 35%, and 57% with treatment of PM-8 after 48, and 72 h, respectively. One of the anti-tumor activity of PM-8 result from the activation of apoptotic pathway. It is thought that polyoxomolybdates will be applied as a novel anti-tumor agent especially against cancers which are difficult to be treated clinically.

Electronic Properties and Stability of DititaniumIV Substituted α-Keggin Polyoxotungstate with Heteroatom Phosphorus by DFT

The electronic properties, redox properties, protonation, and stability of five [alpha-PTi(2)W(10)O(40)](7)(-) isomers have been investigated employing density-functional theory (DFT) method. The results reveal that the stability of [alpha-1,2-PTi(2)W(10)O(40)](7)(-) and [alpha-1,6-PTi(2)W(10)O(40)](7)(-) is weaker and the redox ability is higher among five isomers, while for [alpha-1,5-PTi(2)W(10)O(40)](7-), [alpha-1,4-PTi(2)W(10)O(40)](7)(-), and [alpha-1,11-PTi(2)W(10)O(40)](7)(-) the stability is higher, but the redox ability is weaker. At the same time, Ti-substituted systems are preferentially reduced in the tungsten centers. A simple analysis of molecular electrostatic potential maps of [alpha-PTi(2)W(10)O(40)](7)(-) isomers suggests that the preferred protonation site corresponds to bridging oxygens (OTi(2) and OTiW) and terminal oxygens (OTi), especially bridging oxygens bonded to titaniums (OTi(2)) in [alpha-1,2-PTi(2)W(10)O(40)](7)(-) and [alpha-PTi(2)W(10)O(40)](7)(-). It is proposed that the most stable structure is formed preferentially after protonation of the Ti-O site from the study of the protonated species, [alpha-1,4-HPTi(2)W(10)O(40)](6)(-). By means of total bonding energies of [alpha-PTi(2)W(10)O(40)](7)(-) isomers, the relative sequence of stability has then been shown to be [alpha-1,4-PTi(2)W(10)O(40)](7)(-) > [alpha-1,5-PTi(2)W(10)O(40)](7)(-) > [alpha-1,11-PTi(2)W(10)O(40)](7)(-) > [alpha-1,2-PTi(2)W(10)O(40)](7)(-) > [alpha-1,6-PTi(2)W(10)O(40)](7)(-). In addition, the one-electron-reduced species of [alpha-PTi(2)W(10)O(40)](7)(-) are also discussed.

Synthesis, characterization and antiviral activity against influenza virus of a series of novel manganese-substituted rare earth borotungstates heteropolyoxometalates

A series of novel manganese-substituted mixed-valence rare earth borotungsto-heteropoly blues, Ln2H3[BW9(VI)W2(V)Mn(H2O)O39] x 12H2O (Ln(2), Ln = La, Ce, Pr, Nd, Sm, Eu and Gd), as well as their corresponding heteropoly acids (Ln(0)), have been prepared and characterized by cyclic voltammetry (CV), infrared (IR), ultraviolet (UV), thermal gravimetric (TG) and differential thermal (DTA) analysis, X-ray photoelectron spectroscopy (XPS) and electrochemistry. It's shown that the heteropoly blues anion in Ln(2) still retains the alpha-Keggin structure but with a slight distortion as heteropoly acids do, and Mn and W atoms distribute statistically in the whole molecular. At the same time, the cell toxicity and antiviral activity of these rare earth borotungstateheteropoly blues against influenza virus type A and type B in MDCK cells have been investigated using plaque reduction assay. The results elucidated that these complexes exhibit a significantly inhibitory activity and almost no cytotoxicity comparable with those obtained from virazole, and the anti-virus activity depend on the structure of these complexes.

Broad spectrum anti-RNA virus activities of titanium and vanadium substituted polyoxotungstates

Seven polyoxotungstates substituted with vanadium or titanium atoms were examined for their activity against Flaviviridae (Dengue fever virus, DFV), Orthomyxoviridae (influenza virus type A, fluV-A), Paramyxoviridae (respiratory syncytial virus, RSV, parainfluenza virus type 2, PfluV-2 and canine distemper virus, CDV) and Lentiviridae (human immunodeficiency virus type 1, HIV-1) families. Among the seven polyoxotungstates examined, PM-43 [K(5)[SiVW(11)O(40)]], PM-47 [K(7)[BVW(11)O(40)]], and PM-1001 [K(10)Na(VO)(3)(SbW(9)O(33))(2)]26H(2)O contained vanadium. PM-1002 had the same core structure of (VO)(3)(SbW(9)O(33))(2) as PM-1001; however, three V atoms of PM-1001 consisted of two V(IV) and one V(V) and those of PM-1002 consisted of three V(IV). On the other hand, PM-518 [[Et(2)NH(2)](7)[PTi(2)W(10)O(40)]], PM-520 [Pri(2)NH(2)](5)[PTiW(11)O(40)] and PM-523 [PriNH(3)](6)H[PTi(2)W(10)O(38)(O(2))(2)]H(2)O all contained titanium. All compounds showed broad spectrum antiviral activity against all viruses examined except for PMs-43, -518 and -523 which did not exhibit inhibitory activity at >/=50 microM against PfluV-2, CDV and DFV, respectively. All compounds were inhibitory against HIV replication at an EC(50) of less than 2.0 microM. Among them, PMs-1001 and -1002 showed the most potent inhibition. The compounds were not toxic for MDCK, HEp-2 and Vero cells at a concentration of 200 microM. For the exponentially growing MT-4 cells, the vanadium containing polyoxometalates (PMs-43, 47, 1001, 1002) showed toxicity at concentrations between 41 and 47 microM. On the other hand, titanium containing polyoxometalates (PMs-518, -520, -523) were not toxic at 100 microM. The mechanism of anti-HIV action of PM-1001 was analyzed: it affected the binding of HIV to the cell membrane and syncytium formation between HIV-infected and uninfected cells.

Antiviral activity of mixed-valence rare earth borotungstate heteropoly blues against influenza virus in mice

The acute and accumulated toxicity of the rare earth borotungstate heteropoly blues, HPB-2, Ce2H3[BW9(VI)W2(V)Mn(H2O)O39].12H2O, which is active against influenza virus in Kunming mice, were investigated in Kunming mice following oral and intraperitoneal administration. The activity of HPB-2 against influenza virus (FM1) in the mice was then investigated. HPB-2, given either orally (p.o.) or intraperitoneally (i.p.), was shown to have activity. HPB-2 was shown to be more effective than the positive control, ribavirin, and it was also found that i.p. administration was more effective than p.o. administration.

Potent anti-HIV (type 1 and type 2) activity of polyoxometalates: structure-activity relationship and mechanism of action

A series of polyoxometalates have been synthesized and evaluated for their inhibitory effects on HIV-1(III(B)) and HIV-1(ROD) replication in MT-4 cells. All compounds showed activity against HIV-1 and HIV-2, but the antiviral potency of the heteropolytungstates varied considerably depending on their chemical structure. The antiviral activity of single, double, and triple Keggin-type of compounds against HIV-1(III(B)) replication was comparable (IC(50): 0.4-0.5 microgram/mL), whereas HIV-2(ROD) appeared to become less sensitive with the increasing number of Keggin structures per compound. The same trend was observed for single and double Dawson structures. Some of these compounds were examined for their inhibitory effect on the replication of HIV-1(RF) and SIV(MAC(251)) in MT-4 cells. Their anti-HIV-1(RF) and anti-SIV(MAC(251)) potencies were comparable to those for the HIV-1(III(B)) or HIV-2(ROD) strain, respectively. The polyoxometalates represent a class of polyanionic compounds, which block the binding of the envelope glycoprotein gp120 of HIV to CD4(+) cells. The compounds interfered with the binding of anti-CD4 mAb to the OKT4A/Leu3a epitope of the CD4 receptor, compound 24 being the most active in this regard, and inhibited the binding of anti-gp120 mAb to infected MT-4 cells. None of the polyoxometalates inhibited the binding of a specific CXCR4 mAb to SUP-T1 cells, suggesting that they do not interact with CXCR4, the main co-receptor for T-tropic HIV strains, and thus act as virus binding, and not as fusion, inhibitors.

Recent progress in antiviral chemotherapy for respiratory syncytial virus infections

The recent progress in antiviral chemotherapy against respiratory syncytial virus (RSV) infections was reviewed. RSV infections among high risk individuals, such as premature babies, infants with congenital disease of cardiopulmonary system or immune system and the aged, hospitalised patients with immunosuppressed status are threatened, with high mortality rates and thus need anti-viral chemotherapy. Clinical efficacy of ribavirin and humanized monoclonal antibody (mAb) against RSV infections as well as experimental reports of novel anti-RSV compounds under investigation such as membrane fusion inhibitors were introduced.

Synergistic anti-influenza virus A (H1N1) activities of PM-523 (polyoxometalate) and ribavirin in vitro and in vivo

A Kegin-type polyoxometalate, PM-523, in combination with ribavirin, was tested for its therapeutic effectiveness against influenza virus (FluV) A (H1N1) infection in tissue culture and in mice. PM-523 [(PriNH3)6H [PTi2W10O38(O2)2] x H2O, where Pri is isopropanol] and ribavirin individually inhibited FluV A-induced cytopathic effects in Madin-Darby canine kidney (MDCK) cells at median effective concentrations (EC50s) of 30 and 34 microM, respectively, and at 70% effective concentrations (EC70s) of 48 and 72 microM, respectively. On the other hand, a combination of PM-523 and ribavirin at a ratio of 1:16 exhibited lower EC50s and EC70s than each compound used singly, and combination indices were less than 1. A wide range of combinations of PM-523 and ribavirin at ratios of from 1:128 to 1:1 exhibited additive or synergistic anti-FluV effects in MDCK cells. When these compounds were tested for their anti-FluV A activities in vivo by aerosol exposure of mice which had been infected with a lethal dose of FluV A by an intranasal route, a 1:16 combination of PM-523 and ribavirin was found to have a significantly better therapeutic effect than a single dose of either compound used singly with respect to both the survival rate of the mice and the virus titer in the lungs of the infected mice. PM-523 was effective for the treatment of experimental FluV infection, and in combination with ribavirin, PM-523 exhibited enhanced anti-FluV effects in vitro and in vivo compared with the effect of PM-523 alone.

Protection and therapy of experimental herpesvirus infections in mice with immunomodulating Propionibacterium avidum KP-40 and/or acyclovir

Protection and therapy of NMRI mice with experimental herpes virus (HSV-1) encephalitis were investigated using heat-killed, lyophilized Propionibacterium avidum KP-40 (PA) and/or the herpes-specific antiviral substance acyclovir (ACL) as immunomodifier. Poly I:C as a potent macrophage activator was used as a reference compound for PA. Survival of experimental HSV-1 infections during 18 days following the inoculation of viruses was used for the evaluation of the effects of immunotherapy. The applied model of HSV-1 infection resulted in a mortality of about 87% of NMRI mice at 7-16 days following the inoculation of the virus. Treatment with ACL or Poly I:C at the day of HSV-1 infection resulted in a lowering of the mortality rate to about 40% (p < 0.05). PA applied 4 days before HSV-1 infection lowered the mortality rate to 27%, while treatment 2 days after infection was less effective and the mortality rate reached 44%, although still being significantly lower (p < 0.01) than in untreated controls. A combined treatment with ACL and PA on the day of HSV-1 infection protected 93% of animals against the development of clinically detectable herpesvirus encephalitis.

9-(2-Phosphonylmethoxyethyl) adenine increases the survival of influenza virus-infected mice by an enhancement of the immune system

PMEA (9-(2-phosphonylmethoxyethyl)adenine) is a potent inhibitor of DNA viruses and retroviruses able to enhance natural immune functions such as natural killer cell activity and interferon production. The results reported in this paper show that the treatment with PMEA significatively decreased the mortality of mice challenged with influenza A/PR8 virus (an RNA virus, non sensitive to the antiviral effect of PMEA) compared to untreated, infected controls (median survival 8.64 days and 7.61 days, respectively), and reduced lung weight and consolidation (two surrogate markers of virus infection). Furthermore, virus titer obtained from lung homogenates was substantially decreased in PMEA-treated mice compared to controls. Finally, enhancement of natural killer cell activity was achieved in PMEA-treated A/PR8-infected mice compared to A/PR8-infected controls. Overall, results suggest that PMEA decreases the influenza virus-related mortality and morbidity through the enhancement of some immune functions, and that this effect might be additive or even synergystic with the direct inhibitory effect of DNA viruses or retroviruses induced by PMEA itself. This supports the importance of evaluating this drug in patients with diseases related to herpesviruses or to human immunodeficiency virus.