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Species distribution modelling is a very useful tool in vector management. Ticks are vectors of various pathogens which cause serious problems in livestock production in tropical countries. They have a high dispersal potential which is mainly facilitated by the movement of animals from one area to another. In light of the observed geographic expansion of Rhipicephalus microplus in Zimbabwe, we used species distribution modelling techniques to identify areas which may provide suitable habitats for the occurrence of this invasive tick species as well as the autochthonous Rhipicephalus decoloratus. Our results suggest that, despite the geographic expansion of R. microplus, climate will continue to be a limiting factor for the further expansion of this tick species. We expect its distribution to be restricted to the most favourable areas in the eastern and northern parts. The greater part of Zimbabwe is suitable for R. decoloratus, although in areas where R. microplus occurs, displacement of the former by the latter will be expected to occur. A heterogeneous climate, unregulated movement of cattle and episodic droughts are suggested to be possible factors for the continued existence of R. microplus and R. decoloratus in Zimbabwe and the partial displacement.

International audience; Ticks are economically and medically important ectoparasites due to the injuries inflicted through their bite, and their ability to transmit pathogens to humans, livestock, and wildlife. Whereas hard ticks have been intensively studied, little is known about soft ticks, even though they can also transmit pathogens, including African Swine Fever Virus (ASFV) affecting domestic and wild suids or Borrelia bacteria causing tick-borne relapsing fever (TBRF) in humans. We thus developed a regional model to identify suitable spatial areas for a community of nine Ornithodoros tick species (O. erraticus, O. sonrai, O. alactagalis, O. nereensis, O. tholozani, O. papillipes, O. tartakovskyi, O. asperus, O. verrucosus), which may be of medical and veterinary importance in the Western Palearctic region. Multi-Criteria Decision Analysis was used due to the relative scarcity of high-quality occurrence data. After an in-depth literature review on the ecological requirements of the selected tick community, five climate related factors appeared critical for feeding activity and tick development: (i) a spring temperature exceeding 10 degrees C to induce the end of winter soft tick quiescent period, (ii) a three-months summer temperature above 20 degrees C to allow tick physiological activities, (iii) annual precipitation ranging from 60 mm to 750 mm and, in very arid areas, (iv) dry seasons interrupted by small rain showers to maintain minimum moisture inside their habitat along the year or (v) residual water provided by perennial rivers near habitats. We deliberately chose not to include biological factors such as host availability or vegetation patterns. A sensitivity analysis was done by performing multiple runs of the model altering the environmental variables, their suitability function, and their attributed weights. To validate the models, we used 355 occurrence data points, complemented by random points within sampled ecoregions. All models indicated suitable areas in the Mediterranean Basin and semi desert areas in South-West and Central Asia. Most variability between models was observed along northern and southern edges of highly suitable areas. The predictions featured a relatively good accuracy with an average Area Under Curve (AUC) of 0.779. These first models provide a useful tool for estimating the global distribution of Ornithodoros ticks and targeting their surveillance in the Western Palearctic region.

Rhipicephalus microplus is one of the most widely distributed and economically important ticks, transmitting Babesia bigemina, B. bovis and Anaplasma marginale. It was recently introduced to West Africa on live animals originating from Brazil. Knowing the precise environmental suitability for the tick would allow veterinary health officials to draft vector control strategies for different regions of the country. To test the performance of modelling algorithms and different sets of environmental explanatory variables, species distribution models for this tick species in Benin were developed using generalized linear models, linear discriminant analysis and random forests. The training data for these models were a dataset containing reported absence or presence in 104 farms, randomly selected across Benin. These farms were sampled at the end of the rainy season, which corresponds with an annual peak in tick abundance. Two environmental datasets for the country of Benin were compared: one based on interpolated climate data (WorldClim) and one based on remotely sensed images (MODIS). The pixel size for both environmental datasets was 1km. Highly suitable areas occurred mainly along the warmer and humid coast extending northwards to central Benin. The northern hot and drier areas were found to be unsuitable. The models developed and tested on data from the entire country were generally found to perform well, having an AUC value greater than 0.92. Although statistically significant, only small differences in accuracy measures were found between the modelling algorithms, or between the environmental datasets. The resulting risk maps differed nonetheless. Models based on interpolated climate suggested gradual variations in habitat suitability, while those based on remotely sensed data indicated a sharper contrast between suitable and unsuitable areas, and a patchy distribution of the suitable areas. Remotely sensed data yielded more spatial detail in the predictions. When computing accuracy measures on a subset of data along the invasion front, the modelling technique Random Forest outperformed the other modelling approaches, and results with MODIS-derived variables were better than those using WorldClim data.The high environmental suitability for R. microplus in the southern half of Benin raises concern at the regional level for animal health, including its potential to substantially alter transmission risk of Babesia bovis. The northern part of Benin appeared overall of low environmental suitability. Continuous surveillance in the transition zone however remains relevant, in relation to important cattle movements in the region, and to the invasive character of R. microplus.

Mosquito (Diptera: Culicidae) distribution data from a recent inventory of native and invading mosquito species in Belgium were compared with historical data from the period 1900-1960 that were retrieved from a revision of the Belgian Culicidae collection at the Royal Belgian Institute of Natural Sciences. Both data sets were used to investigate trends in mosquito species richness in several regions in Belgium. The relative change in distribution area of mosquito species was particularly important for species that use waste waters and used tires as larval habitats and species that recently shifted their larval habitat to artificial larval habitats. More importantly, several of these species are known as vectors of arboviruses and Plasmodium sp. and the apparent habitat shift of some of them brought these species in proximity to humans. Similar studies comparing current mosquito richness with former distribution data retrieved from voucher specimens from collections is therefore encouraged because they can generate important information concerning health risk assessment at both regional and national scale.

Data-driven models for the prediction of bluetongue vector distributions are valuable tools for the identification of areas at risk for bluetongue outbreaks. Various models have been developed during the last decade, and the majority of them use linear discriminant analysis or logistic regression to infer vector–environment relationships. This study presents a performance assessment of two established models compared to a distribution model based on a promising ensemble learning technique called Random Forests. Additionally, the impact of false absences, i.e. data records of suitable vector habitat that are, for various reasons, incorrectly labelled as absent, on the model outcome was assessed using alternative calibration–validation schemes. Three reduction methods were applied to reduce the number of false absences in the calibration data, without loss of information on the environmental gradient of suitable vector habitat: random reduction and stratified reduction based on the distance between absence and presence records in geographical (Euclidean distance) or environmental space (Mahalanobis distance). The results indicated that the predicted vector distribution by the Random Forest model was significantly more accurate than the vector distributions predicted by the two established models (McNemar test, p

The steroids 3,6,17-trihydroxy-stigmasta-4,7,24(28)-triene (A) and 14,15,18,20-diepoxyturbinarin (B) were isolated from the cyclohexane extract of brown alga, Turbinaria conoides (J. Agardh) Kutzing, and have been reported for their antimicrobial activity by us. In this study, the isolated compounds were evaluated for comprehensive antihistaminic, antiviral and cytotoxicity screening. The antihistaminic study was performed using in vitro standard animal models. Evaluation of the potency (EC(50)), affinity (pA(2)) and the maximal response (E(max)) of the histamine alone and in the presence of the compounds were determined. Antiviral activity and cytotoxicity were performed in Crandell-Rees feline kidney (CRFK) cells by a colorimetric formazan-based MTS assay. No significant antiviral activity or cytotoxicity were observed for the compounds in the CRFK cells. Compound A inhibited the histamine-induced concentration at 20 µg mL(-1)(p0.05). The most significant inhibition (97%) was observed for compound B (p0.01) at the same concentration, which was comparable to that of the positive control chlorpheniramine maleate (10 µg mL(-1)). This potentiality suggests that 14,15,18,20-diepoxyturbinarin (B) can be developed as a new lead antihistaminic agent.

Selected 4-thiazolidinone have been synthesized and tested as anti-HIV activity. The results of the in vitro tests showed that one of the compounds, 5, inhibited the enzyme at 0.204 microM concentration with minimal toxicity to MT-4 cell. Furthermore, the QSAR studies indicated the role of PMIZ, Ovality and Total energy content of the compounds in rationalizing the activity.

Acyclic nucleoside phosphonate derivatives containing a pyrimidine base preferably bearing amino groups at C-2 and C-4 (DAPym), and linked at the C-6 position to (S)-[3-hydroxy-2-(phosphonomethoxy)propoxy] (HPMPO), 2-(phosphonomethoxy) ethoxy (PMEO) or (R)-[2-(phosphonomethoxy)propoxy] (PMPO), display an antiviral sensitivity spectrum that closely mimic that of the parental (S)-HPMP-, PME- and (R)-PMP-purine derivatives. Several PMEO-DAPym derivatives proved as potent as PMEA (adefovir) and (R)-PMPA (tenofovir) in inhibiting Moloney murine sarcoma virus (MSV)-induced tumor formation in newborn NMRI mice. The HPMPO-, PMEO- and PMPO-DAPym derivatives represent a novel well-defined subclass among the acyclic nucleoside phosphonates endowed with potent and selective antiviral activity.

Simian varicella virus (SVV) and human varicella-zoster virus (VZV) are closely related viruses that share many structural and functional properties. 5-Substituted 2'-deoxyuridine derivatives (e.g., BVDU, BVaraU) and acyclic guanine nucleoside derivatives (i.e., ACV and GCV) show comparable antiviral efficacy against VZV and SVV in cell culture. In contrast, the novel bicyclic nucleoside analogues (BCNAs) are exquisitely inhibitory to VZV (EC50 in the lower nanomolar range) but completely inactive against SVV. The VZV-encoded thymidine kinase (TK) appeared to be essential for BCNA activation (phosphorylation) and anti-VZV activity. Also SVV TK is able to recognize the BCNAs as substrate, although with a different structure-affinity relationship. Thus, viral TK-catalyzed phosphorylation is necessary but not sufficient for the BCNAs to display antiviral activity. Our data suggest that the eventual target of the BCNAs against VZV is either absent in SVV or, alternatively, is insensitive for the (phosphorylated) BCNAs.

A number of 2-arylidenecyclohexanones (1a-h) were converted into the corresponding Mannich bases (2a-h) and (3a,f). Evaluation against murine L1210 cells as well as human Molt 4/C8 and CEM T-lymphocytes revealed the marked cytotoxicity of the Mannich bases and also the fact that almost invariably these compounds were more potent than the precursor enones (1a-h). Further evaluation of most of the Mannich bases towards a panel of nearly 60 human tumour cell lines confirmed their utility as potent cytotoxins. In this assay, the compounds showed growth-inhibiting properties greater than the anticancer alkylator melphalan. QSAR studies revealed that in some cell lines compounds possessing small electron-attracting aryl substituents showed the greatest potencies. Molecular modeling and X-ray crystallography demonstrated that various interatomic distances and torsion angles correlated with cytotoxicity. A representative compound (2a) demonstrated weak inhibiting properties towards human N-myristoyltransferase and stimulated a tyrosine protein kinase. A single dose of 100 mg/kg of most of the compounds did not prove to be lethal in mice.

A series of novel 3,5-bis(phenylmethylene)-1-(N-arylmaleamoyl)-4-piperidones 3 have been synthesized which displayed potent cytotoxicity towards human Molt 4/C8 and CEM T-lymphocytes as well as murine P388 and L1210 leukemic cells. In contrast, the related N-arylmaleamic acids 4 possessed little or no cytotoxicity in these four screens. Molecular modeling revealed certain interplanar and bond angles and interatomic distances which were perceived to contribute to the observed bioactivity as well as providing suggestions for future structural modifications of the piperidones 3. Evaluation of representative compounds in series 3 and 4 on the activity of human N-myristoyltransferase revealed that, at the maximum concentration utilized, namely 250 microM, only weak inhibiting properties were displayed by some of the compounds in series 4. Various members of series 3 and 4 were well tolerated in mice.

Antiviral activity of the metal chelator ethylenediaminedisuccinic acid (EDDS) was examined in vitro against human cytomegalovirus (HCMV) wild type strains and strains that are resistant against ganciclovir (GCV) and cidofovir (HPMPC). EDDS inhibited the replication of wild-type as well as GCV- and HPMPC-resistant strains with a 50% effective concentration of 7.4-12 microg/ml. At concentrations of 100 microg/ml EDDS, unlike GCV or HPMPC, suppressed HCMV-induced up-regulation of intercellular adhesion molecule-1 (ICAM-1) and reduced T-cell adhesion to HCMV-infected cells in a monolayer adhesion model. In vitro EDDS inhibited murine cytomegalovirus (MCMV) replication (EC50 8.6 microg/ml) and caused in mice some protection against MCMV induced mortality at a non-toxic dose. Since immunopathological factors may play a significant role in HCMV disease it will be of interest to further study whether EDDS is effective in terms of modulation of inflammatory responses to HCMV infections.

The chemical synthesis of some acyclic alpha-(1H-pyrazolo[3,4-d]pyrimidin-4-yl)thioalkylamide nucleosides (10-12)a-c is described. The treatment of IH-pyrazolo[3,4-d]pyrimidin-4-thione 1 with compounds 2a-c gave, regioselectively, ethyl alpha-(1H-pyrazolo[3,4-d]pyrimidin-4-yl)thioalkylates 3a-c, respectively. These heterocycles were alkylated, separately, with alkylating agents 4, 5 and 6 to give, regioselectively, the N1-acyclic nucleosides (7-9)a-c which were deprotected to afford the desired products (10-12)a-c. All synthetic compounds were characterized on the basis of their physical and spectroscopic properties. The products (10-12)a-c were evaluated for their inhibitory effects against the replication of HIV-1 (III(B)), HIV-2 (ROD), various DNA viruses, a variety of tumor-cell lines and M. tuberculosis. No marked biological activity was found.

The potential of a large variety of new compounds and new strategies for the treatment of virtually all major virus infections has been addressed. This includes, for the treatment of HIV infections, virus adsorption inhibitors (cosalane derivatives, cyanovirin-N), co-receptor antagonists (TAK-779, AMD3100), viral fusion inhibitors (pentafuside T-20, betulinic acid derivatives), viral uncoating inhibitors (azodicarbonamide), nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs: emtricitabine, amdoxovir, dOTC, d4TMP prodrugs, tenofovir disoproxil fumarate), non-nucleoside reverse transcriptase inhibitors (NNRTIs: thiocarboxanilide UC-781, capravirine, SJ-3366, DPC 083, TMC 125/R165335), integrase inhibitors (diketo acids), transcription inhibitors (temacrazine, flavopiridol), protease inhibitors (atazanavir, mozenavir, tipranavir); for the treatment of RSV and paramyxovirus infections, viral fusion inhibitors (R170591, VP-14637, NMS03); for the treatment of picornavirus infections, viral uncoating inhibitors (pleconaril); for the treatment of pesti- (hepaci-, flavi-) virus infections, RNA replicase inhibitors (VP-32947); for the treatment of herpesvirus (HSV, VZV, CMV) infections, DNA polymerase inhibitors (A-5021, L- and D-cyclohexenylguanine); for the treatment of VZV infections, bicyclic furopyrimidine analogues; for the treatment of CMV infections, fomivirsen; for the treatment of DNA virus infections at large (papilloma-, polyoma-, herpes-, adeno- and poxvirus infections), cidofovir; for the treatment of influenza, neuraminidase inhibitors (zanamivir, oseltamivir, RWJ-270201); for the treatment of HBV infections, adefovir dipivoxil; for the treatment of HBV and HCV infections, N-glycosylation inhibitors (N-nonyl-deoxynojirimycin); and, finally, IMP dehydrogenase inhibitors and S-adenosylhomocysteine hydrolase inhibitors, for the treatment of various virus infections, including hemorrhagic fever virus infections.

A series of 3,5-bis(arylidene)-4-piperidones 1 and related N-acryloyl analogues 2 were prepared as candidate cytotoxic agents with a view to discerning those structural features which contributed to bioactivity. A number of the compounds were markedly cytotoxic toward murine P388 and L1210 leukemic cells and also to human Molt 4/C8 and CEM neoplasms. Approximately 40% of the IC50 values generated were lower than the figures obtained for melphalan. In virtually all cases, the N-acyl compounds were significantly more bioactive than the analogues 1. In general, structure-activity relationships revealed that the cytotoxicity of series 1 was correlated positively with the size of the aryl substituents, while in series 2, a -sigma relationship was established. In particular, various angles and interatomic distances were obtained by molecular modeling, and the presence of an acryloyl group on the piperidyl nitrogen atom in series 2 affected the relative locations of the two aryl rings. This observation, along with some differences in distances between various atoms in series 1 and 2, may have contributed to the disparity in cytotoxicity between 1 and 2. The results obtained by X-ray crystallography of representative compounds were mainly in accordance with the observations noted by molecular modeling. Selected compounds interfered with the biosynthesis of DNA, RNA, and protein in murine L1210 cells, while others were shown to cause apoptosis in the human Jurkat leukemic cell line. This study has revealed the potential of these molecules for development as cytotoxic and anticancer agents.

Several guanosine analogues, i.e. acyclovir (and its oral prodrug valaciclovir), penciclovir (in its oral prodrug form, famciclovir) and ganciclovir, are widely used for the treatment of herpesvirus (i.e. HSV-1, HSV-2, VZV and HCMV) infections. In recent years, several new guanosine analogues have been developed, including the 3-membered (cyclopropyl) sugar derivative A-5021 and the 6-membered D- and L-cyclohexenyl derivatives. Prominent features shared by all guanosine analogues are the following. They depend for their phosphorylation on the virus-encoded thymidine kinase (TK), which makes them particularly effective against those viruses (HSV-1, HSV-2 and VZV) that encoded for such TK. They are also active against HCMV, whether or not they are subject of phosphorylation by the HCMV-induced UL97 protein kinase. Their antiviral activity can be markedly potentiated by mycophenolic acid, an IMP dehydrogenase inhibitor, and they hold great promise, not only as antiviral agents for the treatment of herpesvirus infections, but also as antitumor agents for the combined gene therapy/chemotherapy of cancer, provided that (part of) the tumor cells have been transfected by the viral TK gene.

We evaluated the molecular mechanism of resistance in herpes simplex virus type 1 (HSV-1) thymidine kinase (TK) gene-transfected murine mammary carcinoma (FM3ATK-/HSV-1 TK+) cells, that were selected for resistance against (E)-5-(2-bromovinyl)-2'-deoxyuridine (BVDU) and ganciclovir (GCV) by prolonged exposure of the cell cultures to dose-escalating concentrations of these compounds. Drug-resistant FM3ATK-/HSV-1 TK+ cells showed marked differences in their sensitivity spectrum to a series of antiherpetic nucleoside analogues. BVDU-resistant FM3ATK-/HSV-1 TK+ cells displayed the same sensitivity profile as wild-type FM3A/0 cells. In contrast, GCV-resistant FM3ATK-/HSV-1 TK+ cells were still sensitive to BVDU, (E)5-(2-iodovinyl)-2'-deoxyuridine (IVDU) and (E)-5-(2bromovinyl)-2'-deoxycytidine (BVDC), a typical feature of FM3A TK cells lacking cytosolic TK. Southern blot and PCR analysis revealed that HSV-1 TK genes were not deleted from the genome of the drug-resistant FM3ATK-/HSV-1 TK+ cells. However, the TK genes in drug-resistant FM3ATK-/HSV-1 TK+ cells were shown to be heavily methylated. Accordingly, RT-PCR demonstrated the complete abrogation of TK mRNA production resulting in a complete loss of TK enzyme activity in drug-resistant FM3A TK-/HSV-1 TK+ cells.

A topological substructural approach to molecular design (TOSS-MODE) has been introduced for the selection and design of anticancer compounds. A quantitative model that discriminates anticancer compounds from the inactive ones in a training series was obtained. This model permits the correct classification of 91.43% of compounds in an external prediction set with only 1.43% of false actives and 7. 14% of false inactives. The model developed is then used in a simulation of a virtual search for Ras FTase inhibitors; 87% of the Ras FTase inhibitors used in this simulated search were correctly classified, thus indicating the ability of the TOSS-MODE model of finding lead compounds with novel structures and mechanism of action. Finally, a series of carbonucleosides was designed, and the compounds were classified as active/inactive anticancer compounds by using the model developed here. From the compounds so-designed, 20 were synthesized and evaluated experimentally for their antitumor effects on the proliferation of murine leukemia cells (L1210/0) and human T-lymphocyte cells (Molt4/C8 and CEM/0); 80% of these compounds were well-classified, as active or inactive, and only two pairs of isomeric compounds were false actives. The chloropurine derivatives were the most active compounds, especially compounds 6c, d.

Recently, the antiviral 5-ethynyl-1-beta-D-ribofuranosylimidazole-4-carboxamide (EICAR) was shown to inhibit the replication of the infectious pancreatic necrosis virus (IPNV). In order to obtain more information about the mechanism of the antiviral action of EICAR we studied its effect on viral macromolecules synthesis. EICAR was found to inhibit IPNV messenger and genomic RNA synthesis. To inhibit viral RNA synthesis, EICAR must be added at least 3 h before the start of RNA synthesis. This suggests that EICAR does not directly affect the viral RNA polymerization process. Moreover, the antiviral action of EICAR was reversed by the exogenous addition of guanosine (5-50 microg/ml), but not adenosine or cytidine (10-100 microg/ml). Our findings suggest that the antiviral action of EICAR is mediated by a reduction of the intracellular guanosine 5'-triphosphate (GTP) pool level, as has been observed with ribavirin and EICAR in other biological systems.

SUMMARY The family Flaviviridae contains three genera: Hepacivirus, Flavivirus, and Pestivirus. Worldwide, more than 170 million people are chronically infected with Hepatitis C virus and are at risk of developing cirrhosis and/or liver cancer. In addition, infections with arthropod-borne flaviviruses (such as dengue fever, Japanese encephalitis, tick-borne encephalitis, St. Louis encephalitis, Murray Valley encephalitis, West Nile, and yellow fever viruses) are emerging throughout the world. The pestiviruses have a serious impact on livestock. Unfortunately, no specific antiviral therapy is available for the treatment or the prevention of infections with members of the Flaviviridae. Ongoing research has identified possible targets for inhibition, including binding of the virus to the cell, uptake of the virus into the cell, the internal ribosome entry site of hepaciviruses and pestiviruses, the capping mechanism of flaviviruses, the viral proteases, the viral RNA-dependent RNA polymerase, and the viral helicase. In light of recent developments, the prevalence of infections caused by these viruses, the disease spectrum, and the impact of infections, different strategies that could be pursued to specifically inhibit viral targets and animal models that are available to study the pathogenesis and antiviral strategies are reviewed.

9-(2-phosphonyomethoxypropyl)adenine (PMPA) and AMD3100 are highly potent and selective antiretroviral agents. Since PMPA is negatively charged and AMD3100 positively charged at physiological pH, their transepithelial transport and their potential for oral drug delivery is very low. In this study, ion pair formation was evaluated as a possible strategy to enhance transepithelial transport of PMPA and AMD3100. Positively charged counter ions such as t-hexyl-, t-heptyl-, t-octylammonium bromide and dodecyl-, tetradecyl-, hexadecyltrimethylammonium bromide were used to form ion pairs with PMPA, while sodium taurodeoxycholate (in vitro experiments) and sodium taurocholate (in vivo experiments) were used as counter ions for AMD3100. The effect of counter ions on transepithelial transport of PMPA (1 mM) and AMD3100 (1 mM) was investigated by measuring the flux across Caco-2 monolayers. An enhancement in drug transport could be observed at a concentration of 2 mM of hexadecyltrimethylammonium bromide (counter ion for PMPA) and 10 mM of sodium taurodeoxycholate (counter ion for AMD3100), but at the concentrations used, the absorption enhancing effect could be attributed to a reduction of the integrity of the monolayers. When AMD3100 transport was tested at a concentration of 200 μM, no flux was observed, even in the presence of relatively high concentrations of counter ion (20 times the concentration of AMD3100). Results obtained from partitioning studies of the drugs in the presence or absence of counter ion revealed that competition by other ions was responsible for the absence of an effect: when pure water was used as the aqueous phase, a reduction up to 24.4±1.4% and 17.0±1.3% of the initial aqueous concentration was observed for PMPA and AMD3100, respectively; however, as soon as other ions were present in the aqueous phase, the effect of the counter ion was diminished (25–50 mOsm) or completely abolished (270–305 mOsm). The absorption enhancing effect of counter ions was also studied in vivo: pharmacokinetic studies in rabbits showed that the oral bioavailability of AMD3100 in the presence of 4 equivalents of taurocholic acid remained very low and was only 3.2-fold better (i.e. 3.6%) in comparison to pure AMD3100. In view of the results obtained in the Caco-2 system, this absorption enhancement can be attributed to an effect on monolayer integrity rather than to the potential to form ion pairs. We can conclude that the formation of ion pairs may not be very efficient as a strategy to enhance transepithelial transport of charged hydrophilic compounds, as competition by other ions may abolish the beneficial effect of counter ions.

Fortyeight acyclic nucleoside phosphonates (putative prodrugs of acyclic nucleoside triphosphate inhibitors of DNA replication) have been evaluated for in vitro antiplasmodial activity. Only certain purine derivatives with a hydroxyl group attached to the acyclic sugar moiety displayed antiplasmodial activity. The two most active analogs were ( S )-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine (( S )-HPMPA, IC 50 =0.18±0.07 μM) and ( S )-3-deaza-HPMPA (IC 50 =0.29±0.08 μM). Their cyclic derivatives, containing an ester bond between the phosphonate and the hydroxyl group, were slightly less active. All tested compounds that lacked the hydroxyl group, including potent antiretrovirus analogs such as 9-(2-phosphonylmethoxyethyl)adenine (PMEA) and the ( S )-HPMPA derivatives ( R )-PMPA and ( S )-FPMPA, did not show any activity, even at very high concentrations (>250 μM). Similarly, pyrimidine analogs of ( S )-HPMPA, such as ( S )-HPMPT, ( S )-HPMPU and the anti-herpesvirus analog ( S )-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine (( S )-HPMPC), were devoid of any antiplasmodial activity. In addition, 11 acyclic nucleoside (non-phosphorylated) analogs—which in contrast to the acyclic nucleoside phosphonates require the presence of a monophosphorylating enzyme for the first activation step—were tested. None of them inhibited the growth of the parasite. In short three chemical entities seem to be imperative for antiplasmodial activity: a purine base, a hydroxyl group in the acyclic side chain and a phosphonate group terminating this chain.

Spathodea campanulata stem bark decoction (SCD) has shown hypoglycemic activity in mice. It was separated by column chromatography into different fractions, which were evaluated for their hypoglycemic, anticomplement and anti-HIV activities. The most polar fraction exerted by far the most prominent effect in different biological models.

Orf virus, a member of the Parapoxvirus genus, causes a contagious pustular dermatitis in sheep, goats, and humans. Previous studies have demonstrated the activity of ( S )-1-[3-hydroxy-2-(phosphonomethoxy)propyl]cytosine (HPMPC; cidofovir; Vistide) against orf virus in cell culture and humans. We have evaluated a broad range of acyclic nucleoside phosphonates (ANPs) against several orf virus strains in primary lamb keratinocytes (PLKs) and human embryonic lung (HEL) monolayers. HPMPC, ( S )-9-[3-hydroxy-2-(phosphonomethoxy)propyl]-2,6- diaminopurine (HPMPDAP), and ( R )-9-[3-hydroxy-2-(phosphonomethoxy)propoxy]-2,4-diaminopyrimidine (HPMPO-DAPy) were three of the most active compounds that were subsequently tested in a virus yield assay with PLK and HEL cells by virus titration and DNA quantification. HPMPC, HPMPDAP, and HPMPO-DAPy were evaluated for their activities against orf virus replication in organotypic epithelial raft cultures from differentiated PLK cells. At the highest concentrations (50 and 20 μg/ml), full protection was provided by the three drugs, while at 5 μg/ml, only HPMPDAP and HPMPC offered partial protection. The activities of the three compounds in the raft culture system were confirmed by quantification of infectious virus and viral DNA. These findings provide a rationale for the use of HPMPC and other ANPs in the treatment of orf (contagious ecthyma) in humans and animals.

One, two-disubstituted carbocyclic nucleoside analogues bearing a 2-amino-6-substituted (chloro, hydroxy or amino) purine or 8-azapurine base were prepared by constructing the base about (±)-2-aminocyclopentane methanol, and their activities against a selection of viruses and tumor cells were determined in vitro .

Nucleoside and nucleotide analogues, which are inhibitors of human immunodeficiency virus reverse transcriptase, are highly active inhibitors of visna virus replication in cell cultures. One such analogue, the acyclic nucleoside phosphonate PMEA, has also been found to have a prophylactic effect on visna virus infection in lambs. In the present study, lambs were injected subcutaneously with 10 mg/kg PMEA three times a week starting 4 weeks after inoculation with visna virus, when brain infection had been established. After 3 weeks of treatment there was a reduction in the amount of virus isolated from blood cells of PMEA-treated lambs compared to controls and during the remaining 7 months of drug treatmentthere was significantly less virus isolated from the blood cells of treated lambs than of controls. Antibody response against visna virus was also slower in the treated than in the untreated control group. On the other hand, there was no difference in the amount of virus isolated from various organs of the two groups and the severity of CNS lesions in sheep treated with PMEA for 8 months was comparable to that found in untreated controls, even though PMEA reached concentrations in the cerebrospinal fluid which were well in excess of the EC50 value of the drug for visna virus.

The acyclic nucleoside phosphonate 9-(2-phosphonyl-methoxyethyl)adenine (PMEA) is a potent and selective antiretroviral agent which is currently evaluated in its oral prodrug form, bis(POM)PMEA (adefovir dipivoxil), in phase II and III clinical trials in human hepatitis B virus (HBV)- and human immunodeficiency virus (HIV)-infected individuals, respectively. We have now found that PMEA is also a potent inhibitor of growth of the highly aggressive choriocarcinoma tumor arising from rat choriocarcinoma RCHO cells grafted under the kidney capsule of syngeneic WKA/H rats. In untreated rats, massive invasive RCHO tumors, covering the whole surface of the kidney and resulting in a marked enlargement of the kidney, were observed at day 10 after tumor cell grafting. Daily treatment with PMEA at 25 mg/kg/ day afforded a marked reduction in tumor size (i.e., smaller tumors and slight, if any, enlargement of the kidney). Increasing the PMEA dose to 50, 100 or 250 mglkglday resulted in a gradual increase of the antitumor effect of the compound. At the highest dose tested, i.e., 250 mg/kg/day, PMEA completely suppressed tumor growth. The antitumor activity of PMEA persisted for at least 10 days after termination of drug treatment. In addition, delayed treatment with PMEA at a dose of 200 mg/kg/day, started at a time point where choriocarcinoma tumors had already developed, stopped further growth and even induced regression of the tumors. PMPA, a closely related structural analogue of PMEA, failed to inhibit choriocarcinoma tumor growth. This observation points to the specificity of PMEA as an antitumor agent. In view of our findings, the therapeutic potential of PMEA for the treatment of neoplastic diseases appears to merit further investigation.

The synthesis, hydrolysis, and antiviral evaluation of novel, lipophilic cycloSal-d4TMP derivatives 3a-h of the anti-HIV dideoxynucleoside 2',3'-dideoxy-2',3'-didehydrothymidine (d4T, 1) are reported. This pro-nucleotide concept has been designed to deliver d4TMP (2) by selective chemical hydrolysis. All compounds 3a-h were synthesized using phosphorus(III) chemistry in good yields and in somewhat lower yields using phosphorus(V) chemistry starting from substituted salicyl alcohols 6a-h. The phosphotriesters 3 were obtained without stereochemical preference with respect to the configuration at the phosphorus center as 1:1 diastereomeric mixtures. However, a few of the triesters 3 could be separated into the diastereomers by means of semipreparative HPLC. In a 1-octanol/phosphate buffer mixture, all compounds 3 exhibited 9-100-fold higher lipophilicity as judged from their Pa values as compared to d4T (1). Furthermore, in hydrolysis studies 3 decomposed under mild aqueous basic conditions releasing solely d4TMP (2) and the diols 6 following the designed tandem reaction sequence. A correlation of the electronic properties introduced by the substituents and the half-lives of triesters 3 was observed. Thus, by varying the substituent, the half-lives of 3 could be adjusted over a wide range of compounds still delivering d4TMP (2) selectively. Phosphotriesters 3 exhibited considerable activity against HIV-1 and HIV-2 in wild-type human T-lymphocyte (CEM/O) cells as well as mutant thymidine kinase-deficient (CEM/TK-) cells. Surprisingly, we observed a 3-80-fold difference in antiviral activity between the two diastereomers. Our data clearly prove that the cycloSal-d4TMPs deliver exclusively the nucleotide d4TMP not only under simulated hydrolysis conditions but also under cellular conditions and thus fulfill the thymidine kinase-bypass premise. Therefore, the cycloSal-nucleotide concept is the first reported pro-nucleotide system that delivers the dideoxynucleotide by a pH-driven, chemically activated, tandem reaction without the requirement of an enzymatic contribution.

Novel chain-extended nucleoside phosphoramidates of the anti-human immunodeficiency virus (HIV) drug d4T (stavudine) have been prepared as possible membrane-permeable prodrugs of the bio-active free 5′-monophosphates. Phosphorochloridate chemistry gave the target compounds in moderate to high yields, and all materials were fully characterized by spectroscopic and analytical methods. The compounds are related to the previously reported phenyl methoxyalaninyl derivative of d4T, which was shown to be a potent and selective inhibitor of HIV. In this study theamino acid nitrogen and ester moieties were separated by methylene spacers of between two and six carbon atoms. In vitro evaluation of these compounds indicated an almost complete lack of anti-HIV activity, the compounds being several orders of magnitude less potent than the corresponding α-amino acid derivatives. The reasons for the virtual lack of anti-HIV activity appear to involve poor enzyme-mediated hydrolysis.

Ganciclovir (GCV) and its lipophilic elaidic acid ester prodrug E-GCV were evaluated for their antiherpetic, cytostatic and metabolic properties, E-GCV proved exquisitely inhibitory to the replication of herpes simplex virus type 1 (HSV-1) and HSV-2 in cell cultures (50% effective concentration (EC50): 0.002 microM). It was five- to 10-fold more effective than its parent drug GCV. E-GCV was at least 2000-fold more cytostatic to HSV-1 or HSV-2 thymidine kinase (tk) gene-transfected mammary carcinoma FM3A tk-/HSVtk+ tumor cells than to the corresponding nontransfected tumor cells. The cytostatic activity of E-GCV to the HSVtk gene-transfected tumor cells was far superior to that of GCV. Metabolic studies revealed that both GCV and E-GCV were converted to the mono-, di- and tri-phosphate derivatives of GCV to a markedly higher extent in FM3Atk-/HSV-1 tk+ cells than in wild-type FM3A/0 cells. Strikingly, mono-, di- and tri-phosphate metabolites of GCV were retained for a substantially longer time in E-GCV-treated cells (half-life approximately 50 h) than in GCV-treated cells (half-life approximately 20 h). The longer retention time of the GCV metabolites most likely explains why E-GCV is superior to GCV against herpes simplex virus replication and HSVtk gene-transfected tumor cell proliferation. Taking into account the marked stability of E-GCV in human plasma and its much higher lipophilicity than GCV, E-GCV should be considered as an effective lipophilic prodrug of GCV with a markedly enhanced cytostatic activity in HSVtk gene-transfected tumor cells compared with parental ganciclovir. Its usefulness in the combined gene/chemotherapy of HSVtk gene-transfected tumors should be further pursued.

African buffaloes (Syncerus caffer) are reservoir hosts of Southern African Territories (SAT) foot-and-mouth disease (FMD) virus strains. In South Africa, infected buffaloes are found in the FMD-infected zone comprising the Kruger National Park (KNP) and its adjoining reserves. When these buffaloes stray into livestock areas, they pose a risk of FMD transmission to livestock. We assessed 645 records of stray buffalo events (3124 animals) from the FMD infected zone during 1998-2008 for (i) their temporal distribution, (ii) group size, (iii) age and gender composition, (iv) distance from the infected zone fence and (v) outcome reported for each event. A maximum entropy model was developed to evaluate spatial predictors of stray buffalo events and assess current disease control zones. Out of all buffaloes recorded straying, 38.5% escaped from the FMD infected zone during 2000/2001, following floods that caused extensive damage to wildlife fences. Escape patterns were not apparently influenced by season. The median size of stray groups was a single animal (IQR [1-2]). Adult animals predominated, comprising 90.4% (620/686) of the animals for which age was recorded. Of the 315 events with accurate spatial information, 204 (64.8%) were recorded within 1 km from the FMD infected zone. During late winter/spring (June-October), stray buffaloes were found significantly closer to the FMD infected zone (median = 0.3 km, IQR [0.1-0.6]). Less than 13% (40/315) of stray groups reached the FMD protection zone without vaccination, posing a higher risk of spreading FMD to these more susceptible livestock. Model outputs suggest that distance from the FMD infected zone, urban areas and permanent water sources contributed almost 85% to the spatial probability of stray buffalo events. Areas with a high probability for stray buffalo events were well covered by current disease control zones, although FMD risk mitigation could be improved by expanding the vaccination zone in certain areas.

The inhibitory effects of polyanionic substances on the replication of herpes simplex virus (HSV) and other viruses were reported almost four decades ago. However, these observations did not generate much interest, because the antiviral action of the compounds was considered to be largely nonspecific. Shortly after the identification of human immunodeficiency virus (HIV) as the causative agent of the acquired immune deficiency syndrome (AIDS) in 1984, heparin and other sulfated polysaccharides were found to be potent and selective inhibitors of HIV 1 replication in cell culture. Since 1988, the activity spectrum of the sulfated polysaccharides has been shown to extend to various enveloped viruses, including viruses that emerge as opportunistic pathogens (e.g., herpes simplex virus [HSV] and cytomegalovirus [CMV]) in immunosuppressed (e.g., AIDS) patients. As potential anti-HIV drug candidates, sulfated polysaccharides offer a number of promising features. They are able to block HIV replication in cell culture at concentrations as low as 0.1 to 0.01 mu g ml(-1) without toxicity to the host cells at concentrations up to 2.5 mg ml(-1). We noted that some polysulfates show a differential inhibitory activity against different HIV strains, suggesting that marked differences exist in the tar get molecules with which polysulfates interact, They not only inhibit the cytopathic effect of HIV, but also prevent HIV induced syncytium (giant cell) formation. Furthermore, experiments carried out with dextran sulfate samples of increasing molecular weight and with sulfated cyclodextrins of different degrees of sulfation have shown that antiviral activity increases with increasing molecular weight and degree of sulfation. A sugar backbone is not strictly needed for the anti-HIV activity of polysulfates because sulfated polymers composed of a carbon-carbon backbone have also proved to be highly efficient anti-HIV agents in vitro. Other, yet to be defined, structural features may also play an important role. Sulfated polysaccharides may act synergistically with other anti-HIV drugs (e.g., azidothymidine [AZT]). They are known to lead very slowly to virus drug resistance development and they show activity against HIV mutants that have become resistant to reverse transcriptase inhibitors, such as AZT, tetrahydro-imidazo [4,5,1-jk] [1,4] benzodiazepin 2 (1H) thione (TIBO) and others. From studies on their mechanism of action we concluded that polysulfates exert their anti-HIV activity by shielding off the positively charged sites in the V3 loop of the viral envelope glycoprotein (gp120). The V3 loop is necessary for virus attachment to cell surface heparan sulfate, a primary binding site, before more specific binding occurs to the CD4 receptor of CD4(+) cells. This general mechanism also explains the broad antiviral activity of polysulfates against enveloped viruses. Variations in the viral envelope glycoprotein region may result in differences in the susceptibility of different enveloped viruses to compounds that interact with their envelope glycoproteins. The efficacy of polysulfates in the therapy and/or prophylaxis of retroviral infections and opportunistic infections remains to be demonstrated both in animal models and humans. It is important to consider not only treatment of patients who are already infected with HIV, but also prophylaxis and protection from HIV and/or other virus infections. Because (i) sexual transmission is responsible for the large majority of HIV infections worldwide; (ii) this transmission is mostly mediated via mononuclear cells that infect epithelial cells of the genital tract; and because (iii) polysulfates effectively inhibit cell-cell adhesion, polysulfates may be considered as potentially effective in a vaginal formulation to protect against HIV infection. (C) 1997 Elsevier Science Inc.

From a side-by-side comparative study, the acyclic nucleoside phosphonates (R)-9-(2-phosphonylmethoxypropyl)adenine [(R)-PMPA] and 9-(2-methylidene-3-phosphonomethoxypropyl)guanine (MDL 74,968) proved more selective in their inhibitory effect on human immunodeficiency virus types 1 and 2, feline immunodeficiency virus, and Moloney murine sarcoma virus (MSV) in cell cultures than the 9-(2-phosphonylmethoxyethyl) derivatives of adenine (PMEA) and guanine (PMEG). In particular, PMEG proved quite toxic. PMEA, (R)-PMPA, and MDL 74,968 afforded a marked delay in MSV-induced tumor initiation in MSV-infected newborn NMRI mice and substantially delayed associated animal death at doses as low as 4 to 10 mg/kg of body weight. Treatment of the NMRI mice with PMEA, (R)-PMPA, and MDL 74,968 at 25 or 50 mg/kg resulted in a high percentage of long-term survivors.

Polyomavirus infections in humans are due to BK virus (BKV) and JC virus (JCV). Diseases associated with human polyomaviruses occur mostly in immunocompromised adults, e.g., progressive multifocal leukoencephalopathy (PML), caused by JCV, in AIDS patients and hemorrhagic cystitis and uretral stenosis, caused by BKV, in transplant recipients. No therapy is available for these diseases, which necessitates the development of chemical entities that are active against polyomaviruses. Several antiviral compounds were evaluated to determine their effects on the in vitro replication of mouse polyomavirus and the primate viruses simian virus 40 (SV40), SV40 PML-1, and SV40 PML-2. The activity of the different compounds was assessed by a cytopathic effect reduction assay and confirmed in a virus yield assay. Cidofovir [HPMPC; (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine] and its cyclic counterpart emerged as the most selective antipolyomavirus agents. The 50% inhibitory concentrations for HPMPC were in the range of 4 to 7 micrograms/ml, and its selectivity index varied from 11 to 20 for mouse polyomavirus and from 23 to 33 for SV40 strains in confluent cell monolayers. Cell cytotoxicity was up to 15-fold greater in growing cells. Other acyclic nucleoside phosphonates (i.e., HPMPA; [(S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine] and PMEG [9-(2-phosphonylmethoxyethyl)-guanine]) also showed some activity but had low selectivity. None of the other drugs tested against these animal viruses (i.e., acyclovir, ganciclovir, brivudine, ribavirin, foscarnet, and cytarabine) showed significant activity. Thus, HPMPC deserves further evaluation as a candidate drug for polyomavirus infections in the immunocompromised host.

The cattle tick Rhipicephalus (Boophilus) microplus is known for its invasive character and fast displacement of other species of the same subgenus. The most striking invasions were the ones observed in Ivory Coast (Madder et al. 2007, 2011) and Benin (Madder et al. 2012; De Clercq et al. 2012). Several years after being introduced through importation of exotic Brazilian cattle, R. microplus replaced local blue ticks and most importantly did not respond to the acaricide treatment becoming thus for farmers and veterinary services an uncontrollable ectoparasite affecting animal production in general, apart from being an efficient vector of Babesia bovis. Soon after its discovery in West Africa, several projects were initiated to address the issue. The TickRisk project (assessing ecological suitability for the spread of R. microplus in West Africa) (2011–2013) was implemented in Benin to determine the current spread of this species and develop habitat suitability maps of the region while the WECATiC project (assessment of emerging livestock ticks and tickborne disease threats and integrated control strategies in West and Central Africa) (2011–2014) encompasses Benin, Burkina

The new palladium(II) halide complexes with diethyl and dibutyl esters of (α-anilino-N-benzyl)phosphonic acid and diethyl and dibutyl esters of [α-(4-benzeneazoanilino)-N-benzyl]phosphonic acid have been prepared and studied. All organophosphorus ligands form dihalide complexes, trans -Pd(L) 2 X 2 (X = Cl or Br), with monodentate N-bonded ligand through the anilinobenzyl nitrogen in (α-anilino-N-benzyl)phosphonate complexes and through the azo nitrogen in [α-(4-benzeneazoanilino)-N-benzyl]phosphonate complexes, respectively, without participation of the phosphoryl group. Azobenzene containing ligands by Ortho -metallation also form binuclear organo-palladium complexes, [Pd(LH)Cl] 2 , with the metal-metal chloro bridge. The complexes have been identified and characterized by elemental analysis, infrared and 1 H NMR, as well as by magnetic and conductometric measurements. All were tested in vitro for their cytostatic activity against KB and L1210 tumor cell lines. The results show that these complexes inhibit the multiplication of these tumor cells, but only the dichloro adduct of diethyl [α-(4-benzeneazo-anilino)-N-benzyl]phosphonate was found to have activity comparable to that of the antitumor drug cisplatin.

A number of native and modified milk proteins from bovine or human sources were analyzed for their inhibitory effects on human immunodeficiency virus type 1 (HIV-1) and HIV-2 in vitro in an MT4 cell test system, The proteins investigated were lactoferrin, alpha-lactalbumin, beta-lactoglobulin A, and beta-lactoglobulin B.By acylation of the amino function of the lysine residues in the proteins, using anhydrides of succinic acid or cis-aconitic acid, protein derivatives were obtained that all showed a strong antiviral activity against human immunodeficiency virus type 1 and/or 2. The in vitro IC50 values of the aconitylated proteins were in the concentration range of 0.3 to 3 nM. Succinylation or aconitylation of alpha-lactalbumin and beta-lactoglobulin A/B also produced strong anti-HIV-2 activity with IC50 values on the order 500 to 3000 nM. All compounds showed virtually no cytotoxicity at the concentration used.Peptide-scanning studies indicated that the native lactoferrin as well as the charged modified proteins strongly bind to the V3 loop of the gp120 envelope protein, with K-d values in the same concentration range as the above-mentioned IC50. Therefore, shielding of this domain, resulting in inhibition of virus-cell fusion and entry of the virus into MT4 cells, may be the likely underlying mechanism of antiviral action.

We have employed the attenuated vaccine strain 17D of yellow fever virus (YFV) to evaluate the inhibitory effect of a selected series of compounds on YFV in Vero cells. Use of the vaccine strain does not require high-level microbiological containment facilities and should allow extensive screening. In addition, YFV may serve as a model for other flaviviruses including hepatitis C virus (HCV), and thus strategies for the treatment of YFV infections may apply to flavivirus infections in general. In the present study, several compounds belonging to different classes of nucleoside analogues and polyanions were evaluated for their inhibitory effect on the replication of YFV. Compounds that are targeted at: (i) IMP dehydrogenase (ribavirin, EICAR, tiazofurin, selenazofurin and mycophenolic acid), (ii) OMP decarboxylase (pyrazofurin and 6-azauridine), (iii) CTP synthetase (carbodine and cyclopentenyl cytosine), (iv) dihydrofolate reductase (methotrexate) and the (v) sulfated polymers (dextran sulfate and PAVAS) proved inhibitory to the replication of YFV. Mycophenolic acid (EC50: 0.08 microgram/ml). EICAR (EC50: 0.8 microgram/ml) and methotrexate (EC50: 0.07 microgram/ml) were the most effective. The findings that EICAR and mycophenolic acid, despite their potent anti-YFV activity, had little or no effect on the replication of the bunyavirus Punta Toro or herpes simplex virus in Vero cells, indicates that their anti-YFV activity is rather specific and does not merely result from cytotoxicity. Inhibitors of S-adenosylhomocysteine hydrolase (SAH hydrolase) and thymidylate synthase were found to be devoid of anti-YFV activity.

In attempts to detect inhibitors of infectious pancreatic necrosis virus (IPNV) replication, we have evaluated, by an IPNV plaque inhibition assay, a group of compounds that have broad spectrum antiviral activity for both single- and double-stranded RNA viruses. The inosine monophosphate dehydrogenase (IMP dehydrogenase) inhibitors 1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide (ribavirin) and 5-ethynyl-1-beta-D-ribofuranosylimidazole-4-carboxamide (EICAR), and the orotidine monophosphate decarboxylase (OMP decarboxylase) inhibitor 4-hydroxy-3-beta-D-ribofuranosylpyrazole-5-carboxamide (pyrazofurin), were found to inhibit IPNV replication. For EICAR and pyrazofurin the concentrations that inhibited the IPNV plaque formation by 50% (EC50) were 0.01 micrograms/ml and 0.5 micrograms/ml, respectively. The cytotoxic concentrations required to reduce cell viability by 50% (CC50) were 50 micrograms/ml and 100 micrograms/ml, respectively, and the concentrations that reduced [methyl-3H] thymidine incorporation by 50% (IC50) were 0.5-1 and 50 micrograms/ml. Thus, for both compounds the IPNV-inhibitory concentration was 50-100 times lower than the concentration that affected DNA synthesis in growing cells. EICAR and pyrazofurin seem to be good candidates for further evaluation in an in vivo model of IPNV infection.

The syntheses and the antiviral activities of 2-halo derivatives of neplanocin A (1b,c), (6'R)-6'-C-methylneplanocin A (2b), and dehydroxymethylneplanocin A (3b,c) are described. SN2 reaction of the known cyclopentenyl units 12 and 13 with 2-haloadenines under basic conditions gave the protected carbocyclic nucleosides 14b,c and 15b,c, respectively. Starting from the cyclopentenone derivative 5, the optically active tosyloxycyclopentene derivative 11 was prepared, which was similarly condensed with 2-fluoroadenine to give the protected (6'R)-6'-C-methyl derivative 16b. Deprotection of these compounds afforded the target 2-halo derivatives of neplanocin A. Of these new compounds, 2-fluoroneplanocin A (1b) showed an antiviral potency and a spectrum that was comparable to that of neplanocin A (1a). It was particularly active against vaccinia virus, vesicular stomatitis virus, parainfluenza virus, reovirus, arenaviruses (Junin, Tacaribe), and human cytomegalovirus, i.e., those viruses that fall within the purview of the S-adenosyl-L-homocysteine hydrolase inhibitors.

To advance our restricted knowledge on mosquito biodiversity and distribution in Belgium, a national inventory started in 2007 (MODIRISK) based on a random selection of 936 collection points in three main environmental types: urban, rural and natural areas. Additionally, 64 sites were selected because of the risk of importing a vector or pathogen in these sites. Each site was sampled once between May and October 2007 and once in 2008 using Mosquito Magnet Liberty Plus traps. Diversity in pre-defined habitat types was calculated using three indices. The association between species and environmental types was assessed using a correspondence analysis. Twenty-three mosquito species belonging to traditionally recognized genera were found, including 21 indigenous and two exotic species. Highest species diversity (Simpson 0.765) and species richness (20 species) was observed in natural areas, although urban sites scored also well (Simpson 0.476, 16 species). Four clusters could be distinguished based on the correspondence analysis. The first one is related to human modified landscapes (such as urban, rural and industrial sites). A second is composed of species not associated with a specific habitat type, including the now widely distributedAnopheles plumbeus. A third group includes species commonly found in restored natural or bird migration areas, and a fourth cluster is composed of forest species. Outcomes of this study demonstrate the effectiveness of the designed sampling scheme and support the choice of the trap type. Obtained results of this first country-wide inventory of the Culicidae in Belgium may serve as a basis for risk assessment of emerging mosquito-borne diseases.

9-(2-phosphonylmethoxyethyl)adenine (PMEA) is the prototype compound of a series of acyclic nucleoside phosphonate derivatives endowed with potent and selective anti-retroviral activity in vitro and in vivo. We have now found that PMEA is also a potent inducer of differentiation of a number of tumor cells, including human erythroleukemia K562 cells, rat choriocarcinoma RCHO cells and human acute promyelocytic leukemic HL-60 cells. At 10 μM PMEA, rat RCHO cell cultures could be almost fully differentiated, and at 50 μM PMEA, approximately 50% of the K562 cells could be triggered to produce hemoglobin. The differentiating activity of butyric acid was at least partially additive to that of PMEA when both drugs were combined in K562 cell cultures. PMEA needs to be present for at least 2 or 3 days in the K562 cell cultures to achieve optimal differentiating activity. This suggests that either a PMEA metabolite and/or its anti-metabolic effects may be responsible for differentiation of the tumor cells. © 1995 Wiley-Liss, Inc.

The efficacy of 2-amino-7-[(1,3-dihydroxy-2-propoxy)methyl]purine (S2242) was evaluated in several animal models for herpesvirus infections. Compound S2242 was more effective than acyclovir (i) when administered subcutaneously in a model for herpes simplex virus type 1 (HSV-1)-induced mortality in immunocompetent mice and (ii) when applied topically to hairless (hr/hr) mice that had been infected intracutaneously with HSV-2. In SCID (severe combined immune deficient) mice that had been infected with a thymidine kinase-deficient HSV-1 strain, S2242 (administered subcutaneously at a dosage of 50 mg/kg/day) completely protected against virus-induced mortality whereas foscarnet was less effective and acyclovir had no or little protective effect. Compound S2242 was far more effective than ganciclovir in preventing or delaying murine cytomegalovirus-induced mortality in immunocompetent and SCID mice. The compound was more effective when a given dose was fractionated and administered on subsequent days than when this dose was administered in one single injection. A 5-day treatment course with S2242 (10 and 50 mg/kg/day) for newborn mice that had been infected with a lethal dose of murine cytomegalovirus suppressed virus-induced mortality. Compound S2242 had no inhibitory effect on the growth of weanling (at 50 mg/kg for 5 days) and 3- to 4-week-old mice (at doses of 50 to 200 mg/kg for 6 weeks). However, akin to ganciclovir, compound S2242 significantly reduced testicle weight, testicle morphology, and spermatogenesis.

Starting from (±)-cis-2-hydroxymethylcyclohexylamine, a series of cyclohexane-derived cis-1,2-disubstituted carbonucleoside analogues with a 6- or 2,6-purine or 8-azapurine base were synthesized. The antiviral and antitumoral in vitro effects of the new compounds were evaluated.

The cattle tick Rhipicephalus microplus is currently invading the West African region, and little information is available on the spread of this exotic tick in this region. We set out a country-wide field survey to determine its current distribution in Benin. Ticks were collected on cattle from 106 farms selected by random sampling covering all regions of the country. Rhipicephalus annulatus was found on 70 % of all farms, R. decoloratus on 42 %, R. geigyi on 58 %, and R. microplus on 49 %. There is a clear geographic separation between the indigenous Rhipicephalus species and R. microplus. Rhipicephalus annulatus occurs mainly in the northern departments, but it was also observed in lower numbers in locations in the south. The presence of R. decoloratus is limited to the northern region, and in most locations, this tick makes up a small proportion of the collected ticks. The tick R. geigyi tends to be dominant, but occurs only in the four northern departments. The observations concerning R. microplus are entirely different, this species occurs in the southern and central region. The results of this survey confirm the invasive character and displacement properties of R. microplus, since in less than a decade it has colonized more than half of the country and has displaced indigenous ticks of the same genus in many of the sampled locations.

SUMMARYIn the last decade, mobile technology offered new opportunities and challenges in animal health surveillance. It began with the use of basic mobile phones and short message service (SMS) for disease reporting, and the development of smartphones and other mobile tools has expanded the possibilities for data collection. These tools assist in the collection of data as well as geo-referenced mapping of diseases, and mapping, visualization and identification of vectors such as ticks. In this article we share our findings about new technologies in the domain of animal health surveillance, based on several projects using a wide range of mobile tools, each with their specific applicability and limitations. For each of the tools used, a comprehensive overview is given about its applicability, limitations, technical requirements, cost and also the perception of the users.The evaluation of the tools clearly shows the importance of selecting the appropriate tool depending on the envisaged data to be collected. Accessibility, visualization and cost related to data collection differ significantly among the tools tested. This paper can thus be seen as a practical guide to the currently available tools.

2-Amino-7-[(1,3-dihydroxy-2-propoxy)methyl]purine (compound S2242) represents the first antivirally active nucleoside analog with the side chain attached to the N-7 position of the purine ring. Compound S2242 strongly inhibits the in vitro replication of both herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) (50% effective concentration [EC50], 0.1 to 0.2 microgram/ml), varicella-zoster virus (EC50, 0.01 to 0.02 microgram/ml) and thymidine kinase (TK)-deficient strains of HSV (EC50, 0.4 microgram/ml) and varicella-zoster virus (EC50, 0.2 to 0.5 microgram/ml). Potent activity was also observed against murine cytomegalovirus (EC50, 1 microgram/ml), human cytomegalovirus (HCMV) (EC50, 0.04 to 0.1 microgram/ml), and human herpesvirus 6 (EC50, 0.0005 microgram/ml). Compound S2242 (i) was not cytotoxic to confluent Vero, HeLa, or human fibroblast cells at concentrations of > 100 micrograms/ml, (ii) proved somewhat more cytostatic to Vero, HEL, HeLa, and C127I cells than ganciclovir, and (iii) was markedly more cytostatic than ganciclovir to the growth of the human lymphocytic cell lines HSB-2 and CEM degrees. In contrast to ganciclovir, (i) compound S2242 proved not to be cytocidal to murine mammary carcinoma (FM3A) cells transfected with the HSV-1 or HSV-2 TK gene, (ii) exogenously added thymidine had only a limited effect on its anti-HSV-1 activity, and (iii) the compound was not phosphorylated by HSV-1-encoded TK derived from HSV-1 TK-transfected FM3A cells, indicating that the compound is not activated by a virally encoded TK. Compound S2242 inhibited (i) the expression of late HCHV antigens at an EC50 of 0.07 microgram/ml (0.6 microgram/ml for ganciclovir) and (ii) HCMV DNA synthesis at an EC50 of 0.1 microgram/ml (0.32 microgram/ml for ganciclovir), i.e., values that are close to the EC50S for inhibition of HCMV-induced cytopathogenicity. Neither ganciclovir nor S2242 had any effect on the expression of immediate-early HCMV antigens, which occurs before viral DNA synthesis. In time-of-addition experiments, S2242 behaved like ganciclovir and acyclovir; i.e., the addition of the drugs could be delayed until the onset of viral DNA synthesis.

A number of 3,5-diarylidene-4-piperidones (1) and some related quaternary ammonium salts (5) as well as closely related analogs were prepared principally as candidate cytotoxic agents in two screens. The first test system used an average of 54 human tumor cell lines from eight neoplastic diseases, namely leukemia, melanoma, colon, non-small-cell lung, small-cell lung, central nervous system, ovarian, and renal cancers. Selective toxicity was demonstrated by some of the compounds, especially toward leukemia. The second screen used L 1210 lymphoid leukemia cells. In general, the compounds were less cytotoxic than the reference drug melphalan in both screens. Linear plots were made between the Hammett (σ), fragment (f), and molar refractivity (MR) constants of the nuclear substituents in series 1 and 5with the IC50 figures of both the human tumor cell lines and L 1210 cells. Evaluation against the human tumor cell lines revealed that increases in the f values were correlated with elevation of cytotoxicity in both series 1 and 5; MR constants were also important in series 5. In the L 1210 screen, σ and MR constants were positively correlated with cytotoxicity. X-ray crystallography was undertaken on 3,5-bis-[[4′-(methylthio)phenyl]methylene]-1-methyl-4-piperidone methiodide (5d), which had significant cytotoxicity, and 3,5-bis(4-pyridylmethylene)-1-methyl-4-piperidone methiodide (6), which was virtually inactive in both screens. A number of structural features were noted, and in particular a smaller interplanar angle made by one of the arylidene groups with the central piperidine ring in the case of 5d than either of the 4-pyridylmethylene moieties in 6 may contribute to the variation in cytotoxicity between these two compounds. Eleven compounds which were examined for activity against a panel of 12 viruses were shown to display only marginal potencies or to be inactive at the highest concentrations utilized. Two compounds with slight activity both had the hydrophilic carboxylate ion in the aryl rings. From this study, various conclusions pertaining to future molecular modification with a view to increasing cytotoxic potency were made.

For the majority of native species, human-created habitats provide a hostile environment that prevents their colonization. However, if the conditions encountered in this novel environment are part of the fundamental niche of a particular species, these low competitive environments may allow strong population expansion of even rare and stenotopic species. If these species are potentially harmful to humans, such anthropogenic habitat alterations may impose strong risks for human health. Here, we report on a recent and severe outbreak of the viciously biting and day-active mosquito Anopheles plumbeus Stephens, 1828, that is caused by a habitat shift toward human-created habitats. Although historic data indicate that the species was previously reported to be rare in Belgium and confined to natural forest habitats, more recent data indicate a strong population expansion all over Belgium and severe nuisance at a local scale. We show that these outbreaks can be explained by a recent larval habitat shift of this species from tree-holes in forests to large manure collecting pits of abandoned and uncleaned pig stables. Further surveys of the colonization and detection of other potential larval breeding places of this mosquito in this artificial environment are of particular importance for human health because the species is known as a experimental vector of West Nile virus and a potential vector of human malaria.

9-(2-phosphonylmethoxyethyl)-2,6-diaminopurine (PMEDAP), a potent inhibitor of human immunodeficiency virus (HIV) replication, was evaluated for its activity against human cytomegalovirus (HCMV) in vitro, and murine cytomegalovirus (MCMV) and rat CMV (RCMV) in vivo. PMEDAP strongly inhibited HCMV-induced cytopathicity in human embryonic lung (HEL) cell cultures (EC50 11 microM) and caused a concentration-dependent suppression of viral DNA synthesis (IC50 20 microM) [corrected]. PMEDAP had no effect on the expression of HCMV-specific immediate early antigens (IEA) as measured on day 1 post-infection, but inhibited the expression of HCMV late antigens as measured on day 6 post-infection (EC50 20 microM) [corrected]. The diphosphate derivative of PMEDAP (PMEDAPpp) selectively inhibited HCMV-induced DNA polymerase (IC50 0.1 microM). PMEDAP proved markedly effective in reducing the mortality rate of NMRI mice that had been infected intraperitoneally or intracerebrally with a lethal dose of MCMV. PMEDAP exhibited greater anti-MCMV activity when administered as a single dose immediately after infection than when this dose was divided over repeated administrations. 9-(2-phosphonylmethoxyethyl)-adenine (PMEA) also prevented MCMV-induced mortality, but only at a dose ten-fold higher than that of PMEDAP. PMEDAP also delayed death in severe combined immune deficiency (SCID) mice that had been infected with MCMV. The effect of PMEDAP on RCMV infections in rats was less pronounced.