[Interaction of HIV-1 reverse transcriptase with new minor groove ligands and their conjugates with oligonucleotides].

The influence of new non-natural regular minor groove binders (MGB), containing 2-4 imidazole, pyrrole or thiazole residues, and their conjugates with oligonucleotides, on the polymerization reaction catalyzed by HIV-1 reverse transcriptase was analyzed. Various model template-primer complexes: poly(A)-oligo(U), poly(A)-oligo(dT), poly(dA)-oligo(U), poly(dA)-oligo(dT) and activated DNA were used. The concentration of oligopeptides, giving 50% inhibition (I50) of the RT-dependent polymerization reaction, was shown to depend strongly on the structure of template-primer complexes, number and type of the heterocycle rings in the MGBs analyzed. The range of I50 for the most of the compounds studied is 7.7 x 10(-3)-1.0 x 10(-5) M. The affinity of MGB is minimal for poly(A)-oligo(U). However, some of imidazole and pyrrole-containing MGBs demonstrated unusually high affinity (I50 = 3 x 10(-9)-4 x 10(-8) M) to the above template-primer in complex with RT. The affinity of conjugates of thiazolecarboxamides with oligonucleotides complementary or partially complementary to the template, is 1-4 orders higher compared to free thiazolecarboxamides. The possible reasons of the dependence of I50 values upon the structure of the template-primer complexes, the structure of MGB, and their conjugates with oligonucleotides are discussed.

Biochemical and random mutagenesis analysis of the region carrying the catalytic E152 amino acid of HIV-1 integrase.

HIV-1 integrase (IN) catalyzes the integration of the proviral DNA into the cellular genome. The catalytic triad D64, D116 and E152 of HIV-1 IN is involved in the reaction mechanism and the DNA binding. Since the integration and substrate binding processes are not yet exactly known, we studied the role of amino acids localized in the catalytic site. We focused our interest on the V151E152S153 region. We generated random mutations inside this domain and selected mutated active INs by using the IN-induced yeast lethality assay. In vitro analysis of the selected enzymes showed that the IN nuclease activities (specific 3'-processing and non-sequence-specific endonuclease), the integration and disintegration reactions and the binding of the various DNA substrates were affected differently. Our results support the hypothesis that the three reactions may involve different DNA binding sites, enzyme conformations or mechanisms. We also show that the V151E152S153 region involvement in the integration reaction is more important than for the 3'-processing activity and can be involved in the recognition of DNA. The IN mutants may lead to the development of new tools for studying the integration reaction, and could serve as the basis for the discovery of integration-specific inhibitors.

Peptides as new inhibitors of HIV-1 reverse transcriptase and integrase.

Current treatments of human immunodeficiency virus type 1 (HIV-1) infection consist in the combination of drugs targeting reverse transcriptase (RT) and protease (PR). Despite the multiple clinical benefits of this combination therapy, the emergence of resistance highlights the need for new anti-HIV agents. Agents able to interfere with additional steps of viral replication, such as integration of viral DNA in the host genome, would improve the antiviral potency of the treatment. In this regard, we have focused our interest on peptide-based compounds that have been shown to exhibit potential inhibition of RT and integrase (IN) activities in vitro and in vivo. Recently, the expansion of powerful technologies which allow the selection of peptides exhibiting high affinity for a target protein have provided a new approach to selecting potential anti-HIV drugs. Furthermore, efforts to characterize the protein-protein interactions involved in efficient reverse transcription and integration, as well as the determination of the enzyme structure, have generated a very useful source of data for the development of peptide inhibitors. Finally, while this class of compounds has long been considered as poor drug candidates, current knowledge on improving the stability and bioavailability of these agents would lead to the effective use of peptides in therapy.

DNA aptamers derived from HIV-1 RNase H inhibitors are strong anti-integrase agents.

HIV-1 integrase, the retroviral-encoded enzyme involved in the integration of the retrotranscribed viral genome into the host nuclear DNA, is an attractive and still unexploited target. To date, very few inhibitors of this enzyme with a potential therapeutic value have been described. During the search for new HIV-1 targets, we recently described DNA oligodeoxynucleotide aptamers (ODN 93 and ODN 112) that are strong inhibitors of the RNase H activity associated with HIV-1 reverse transcriptase. The striking structural homology between RNase H and integrase led us to study the effect of the RNase H inhibitors on the integrase. Shorter DNA aptamers derived from ODNs 93 and 112 (ODNs 93del and 112del) were able to inhibit HIV-1 integrase in the nanomolar range. They had G-rich sequences able to form G-quartets stabilized by the presence of K(+). The presence of these ions increased the inhibitory efficiency of these agents dramatically. Inhibition of enzymatic activities by ODN 93del and ODN 112del was observed in a cell-free assay system using a recombinant integrase and HIV-1 replication was abolished in infected human cells. Moreover, cell fusion assays showed that these agents do not block viral cell entry at concentrations where viral replication is stopped.

DNA aptamers selected against the HIV-1 RNase H display in vitro antiviral activity.

The DNA polymerase of the human immunodeficiency virus type 1 reverse transcriptase (HIV-1 RT) is a target widely used to inhibit HIV-1 replication. In contrast, very few inhibitors of the RNase H activity associated with RT have been described, despite the crucial role played by this activity in viral proliferation. DNA ligands with a high affinity for the RNase H domain of HIV-1 RT were isolated by systematic evolution of ligands by an exponential enrichment strategy (SELEX), using recombinant RTs with or without the RNase H domain. The selected oligonucleotides (ODNs) were able to inhibit in vitro the HIV-1 RNase H activity, while no effect was observed on cellular RNase H. We focused our interest on two G-rich inhibitory oligonucleotides. Model studies of the secondary structure of these ODNs strongly suggested that they were able to form G-quartets. In addition to the inhibition of HIV-1 RNase H observed in a cell free system, these ODNs were able to strongly diminish the infectivity of HIV-1 in human infected cells. Oligonucleotides described here may serve as leading compounds for the development of specific inhibitors of this key retroviral enzyme activity.

Initiation of HIV-2 reverse transcription: a secondary structure model of the RNA-tRNA(Lys3) duplex.

Human immunodeficiency virus type 2 (HIV-2) reverse transcription is initiated from cellular tRNA(Lys3) partially annealed to the RNA viral genome at the primer binding site (PBS). This annealing involves interactions between two highly structured RNA molecules. In contrast to HIV-1, in which the reverse transcription initiation complex has been thoroughly studied, there is still little information regarding a possible model to describe the secondary structure of the template-primer complex in HIV-2. To determine whether HIV-2 RNA sequences flanking the PBS may specifically interact with the natural primer tRNA, we performed site-directed mutagenesis and enzymatic footprinting. An RNA fragment corresponding to the HIV-2 U5 RNA domain and tRNA(Lys3) were probed either in their free form or in the binary complex. Important reactivity changes to nucleases were obtained upon complex formation. In addition to the canonical contacts between the viral PBS and the 3' end acceptor stem of tRNA(Lys3), we identified two additional interacting domains: (i) the U-rich region of the anticodon loop with the A-rich sequence of the internal loop within the U5-prePBS region; (ii) nucleotides 48-54 from the TPsiC domain of tRNA(Lys3) and the 240-247 region of viral U5-RNA. In view of these experimental data and sequence comparison between different HIV-2 isolates, we propose a model for the secondary structure of the HIV-2 template-primer initiation complex.

Antiviral activity of 4-benzyl pyridinone derivatives as HIV-1 reverse transcriptase inhibitors.

In this overview, the antiviral properties of the Curie-pyridinone compounds, a new class of non-nucleoside reverse transcriptase inhibitors (NNRTIs) developed as anti-HIV agents, are described. These compounds are hybrids between hydroxyethoxymethyl-phenylthiothymine (HEPT) and Merck pyridinones. Several structure-activity relationships (SAR) studies between HIV-1 reverse transcriptase (RT) and the Curie-pyridinones are described. The Curie-pyridinones are potent inhibitors of both HIV-1 replication in cell culture and of HIV-1 RT activity in vitro. They are specific to HIV-1 and do not inhibit the replication of HIV-2. The mechanism of inhibition is non-competitive with respect to the natural substrate dGTP. For these reasons, the Curie-pyridinones can be considered as non-nucleoside inhibitors of HIV-1 RT. Moreover, they have the unusual ability to reach the reverse transcription complex inside the extracellular virions and may therefore be useful as retrovirucides. This might lead to the design and synthesis of new drugs able to interact with the retroviral enzyme inside the viral core.

Synthesis and antiviral activity of 4-benzyl pyridinone derivatives as potent and selective non-nucleoside human immunodeficiency virus type 1 reverse transcriptase inhibitors.

Several 4-benzyl analogues of 5-ethyl-6-methyl-4-(phenylthio)pyridin-2(1H)-ones were synthesized and evaluated for their anti-HIV-l activities. Key transformations include metalation at the 4-C-position of 5-ethyl-2-methoxy-6-methyl-3-pivaloylaminopyridine (5) and its coupling with benzyl bromide or benzaldehyde derivatives. Biological studies revealed that some of the new 4-benzylpyridinones show potent HIV-1 specific reverse transcriptase inhibitory properties. Compounds 14, 19, and 27, which inhibit the replication of HIV-1 in CEM-SS cells, with IC(50) values ranging from 0.2 to 6 nM are the most active compounds in this series. Biochemical studies showed that compound 27 strongly inhibited the activity of a recombinant HIV-1 RT. Moreover, the infectivity of isolated HIV-1 particles was severely decreased after exposure to compound 27. Although cross resistance is frequently observed between non-nucleoside reverse transcriptase inhibitors, compound 27 was capable of inhibiting a virus resistant to nevirapine with an IC(50) of 40 nM.

Synthesis and evaluation of oligo-1,3-thiazolecarboxamide derivatives as HIV-1 reverse transcriptase inhibitors.

A set of oligo-1,3-thiazolecarboxamide derivatives able to interact with the minor groove of nucleic acids was synthesized. These oligopeptides contained different numbers of thiazole units presenting dimethylaminopropyl or EDTA moieties on the C-terminus, and aminohexanoyl or EDTA moieties on the N-terminus. The inhibition of such compounds on HIV-1 reverse transcriptase activity was evaluated using different model template primer duplexes: DNA x DNA, RNA x DNA, DNA x RNA and RNA x RNA. The biological properties of the thiazolecarboxamide derivatives were compared to those of distamycin, another minor groove binder which contains three pyrrole rings. Similar to distamycin, the thiazole containing oligopeptides were good inhibitors of the reverse transcription reaction in the presence of DNA x DNA. But in contrast to distamycin, the oligothiazolide derivatives were able to inhibit reverse transcription in the presence of RNA x DNA or DNA x RNA template primers. Both distamycin and oligothiazolecarboxamides had low affinity for RNA x RNA duplexes. The inhibition obtained with the newly synthesized thiazolecarboxamides showed that these compounds were more powerful and versatile inhibitors of the RT-dependent polymerization than the natural minor groove binder distamycin.

Study of HIV-2 primer-template initiation complex using antisense oligonucleotides.

HIV-2 reverse transcription is initiated by the retroviral DNA polymerase (reverse transcriptase) from a cellular tRNALys3 partially annealed to the primer binding site in the 5'-region of viral RNA. The HIV-2 genome has two A-rich regions upstream of the primer binding site. In contrast to HIV-1 RNA, no direct evidence of interactions with the U-rich anticodon loop of tRNALys3 has been described to date. Here we address the question of the potential role of the interactions between these highly structured regions in the initiation of viral DNA synthesis. To evaluate this we used an antisense approach, first validated in our in vitro HIV-1 reverse transcription system. Annealing of the antisense oligonucleotides to the pre-primer binding site (the upstream region contiguous to the HIV-2 primer binding site) was determined in the presence of native tRNALys3 or synthetic primers. Using natural and chemically modified antisense oligonucleotides we found that interactions between the anticodon of tRNALys3 and an A-rich loop of viral RNA led to an important destabilization of the pre-primer binding site; this region became accessible to anti-pre-primer binding site oligonucleotides in a cooperative manner. These studies allowed to identify an A-rich region in HIV-2ROD RNA capable of interacting with tRNALys3. Better knowledge of these interactions is very important for understanding the primer/template positioning in the early steps of HIV-2 reverse transcription.

Inhibition of HIV-1 integrase-catalysed reaction by new DNA minor groove ligands: the oligo-1,3-thiazolecarboxamide derivatives.

Human immunodeficiency virus type 1 (HIV-1) integrase (IN) is an essential enzyme in the life cycle of the retrovirus, responsible for catalysing the insertion of the viral genome into the host cell chromosome. For this reason it provides an attractive target for antiviral drug design. We synthesized a series of novel thiazole (Tz)-containing oligopeptides (TCOs; oligo-1,3-thiazolecarboxamides), specifically interacting within the minor groove of DNA. The oligocarboxamide derivatives contained 1-4 Tz rings and different N- and C-terminal groups. The effect of these oligocarboxamides on the HIV-1 IN-catalysed reaction was investigated. Some of the compounds were able to inhibit the reaction. The inhibitory effect of the TCOs increased with the number of Tz units. The structure of various additional positively and/or negatively charged groups attached to the N- and C-termini of TCOs had a pronounced effect on their interaction with the DNA substrate complexed to IN. Modified TCOs having a better affinity for this complex should provide a rationale for the design of drugs targeting the integration step.

Interaction of oligonucleotides conjugated to substituted chromones and coumarins with HIV-1 reverse transcriptase.

Ten different pyranone-related substituents (chromones or coumarins) were covalently linked to the 5' end of various oligonucleotides (ODN). The interaction of these compounds with human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) was analyzed. A different behavior was found to depend on the structure of the oligonucleotide derivatives. Some compounds activated the enzyme at relatively low concentrations (0.1-0.5 microM), followed by an inhibition of the activity at higher concentrations (5-20 microM), whereas others behave just as inhibitors. Because the presence of some coumarin or chromone derivatives conjugated to ODNs enhanced the interaction with the reverse transcriptase, we analyzed the capacity of such ODN derivatives to be used as primers. The introduction of substituent I, a chromone derivative, the 2-[(3-(aminopropyl)amino]-8-isopropyl-5-methyl-4-oxo-4H-1-benzopyran-3-c arbaldehyde], and II, a coumarin derivative, the 1-(3-aminopropoxy)-2-ethyl-3H-naphto[2,1-b]pyran-3-one, into the 5' end of a noncomplementary ODN allowed these compounds to be used as primers. In the case of complementary primers, the presence of conjugated derivatives enhanced the affinity with Km values that were two to three orders of magnitude lower than that of a complementary primer of the same length. After addition of a ddT-unit to the 3'-terminal end of the ODN, some of these primers became very effective inhibitors of RT with Ki values in the nanomolar range.

High affinity interaction of HIV-1 integrase with specific and non-specific single-stranded short oligonucleotides.

Retroviral integrase (IN) catalyzes the integration of double-stranded viral DNA into the host cell genome. The reaction can be divided in two steps: 3'-end processing and DNA strand transfer. Here we studied the effect of short oligonucleotides (ODNs) on human immunodeficiency virus type 1 (HIV-1) IN. ODNs were either specific, with sequences representing the extreme termini of the viral long terminal repeats, or nonspecific. All ODNs were found to competitively inhibit the processing reaction with Ki values in the nM range for the best inhibitors. Our studies on the interaction of IN with ODNs also showed that: (i) besides the 3'-terminal GT, the interaction of IN with the remaining nucleotides of the 21-mer specific sequence was also important for an effective interaction of the enzyme with the substrate; (ii) in the presence of specific ODNs the activity of the enzyme was enhanced, a result which suggests an ODN-induced conformational change of HIV-1 IN.

Effect of nucleoside analogs and non-nucleoside inhibitors of HIV-1 reverse transcriptase on cell-free virions.

Reverse transcription takes place in the cytoplasm of infected cells, although it has been demonstrated that retroviruses can also initiate reverse transcription prior to infection of target cells. In addition to partial reverse transcripts, full-length proviral molecules have been detected in the plasma and seminal fluid of HIV-1 seropositive patients. Intravirion endogenous reverse transcription appears to be directly correlated with an increased level of infectivity. Therefore, the ability of an inhibitor to reach and inhibit the replication complex in the core of the free-virion may constitute an important part of its capacity to suppress viral infection. In this work we tested the ability of some reverse transcriptase inhibitors to decrease viral infectivity in pretreated highly purified virions. Our results showed that Curie pyridinone [Dollé et al. (1995), J Med Chem 38: 4,679-4,686], a non nucleoside RT inhibitor, strongly inhibited the infectivity of extracellular HIV-1 particles. Other non nucleoside inhibitors (TIBO R82913, HEPT, nevirapine) tested in these conditions were unable to do so. Our data indicate that the effect of Curie pyridinone on intact virions may be related to its capacity to tightly bind the target RT. This approach may lead to the design and synthesis of new drugs able to interact with the retroviral enzyme inside the viral core.

Cross-linking localization of a HIV-1 reverse transcriptase peptide involved in the binding of primer tRNALys3.

Human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) initiates the synthesis of DNA from the 3' end of its specific primer, tRNALys3. The regions of tRNALys3 in close contact with RT are well known, while a precise knowledge of the RT regions interacting with tRNALys3 is not yet available. To address this question we cross-linked the heterodimeric p66/p51 RT to tRNALys3 using cis-aquahydroxydiammino-platinum. Ribonucleoprotein complexes of molecular masses higher than the p66 subunit were obtained. After RNase A digestion of the RT-tRNA complex, a labeled oligoribonucleotide (ORN) was mainly found associated to the p66 subunit. This labeled p66-ORN complex was then proteolyzed with Staphylococcus aureus V8 protease. A highly purified radioactive peptide was obtained after two chromatographic purification steps. Its N-terminal sequence corresponded with amino acid residues 241VQPI244. Using the crystallographic structure of HIV-1 RT, this peptide was localized at the beta14-sheet end, near to the hairpin formed by beta12 and beta13-sheets ("primer grip") and the alphaH-helix. The so called "VQPI peptide" is in the border of the thumb and the palm subdomains of the p66 subunit. This study palliates the absence of a three- dimensional structure of the RT-tRNA complex and led to a peptide in interaction with tRNALys3 present in all HIV-1 RT isolates.

HIV-1 reverse transcriptase is capable of elongating derivatives of sequence specific noncomplementary oligodeoxynucleotides.

We have carried out a comparison of KM and Vmax values for various primers in the polymerization reaction catalyzed by the HIV-1 RT. The affinity of RT for complementary d(pT)6 containing two different 5'-end pyranone derivatives was 2-3 orders of magnitude higher (KM = 3-15 nM) than that of d(pT)6 (KM = 12.6 mM). Oligodeoxynucleotides (ODNs) noncomplementary to poly(A) template were not elongated by RT. However, derivatives of d(CAGGTG) containing the 5'-terminal chromone and coumarin related groups were efficient primers showing KM (30-300 nM) and Vmax (75-93%) values comparable with that for d(pT)10 (800 nM; 100%). The [d(CAGGTG)]ddT ODN derivatives were effective inhibitors of RT. The primer function of derivatives of noncomplementary ODNs appears to be due to the additional interactions of their 5'-terminal groups with the enzyme tRNA-binding site.

Structural constraints in the HIV-1 reverse transcriptase-primer/template complex for the initiation of DNA synthesis from primer tRNALys3.

The topography and functional implications of the complex formed in vitro between human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) and its primer tRNALys3 were studied in this work. On the basis of previous results showing the high affinity both of the native primer, tRNALys3, as well as that of mismatched short oligonucleotide primers for HIV-1 RT, we synthesized chimeric primers containing tRNALys3 linked to U and T residues of different lengths. We found that the affinity of the oligonucleotide primers for HIV-1 RT is dramatically increased when linked to primer tRNA. Our results also show that in the tRNA.RT complex, before annealing tRNALys3 to the retroviral RNA genome, the 3'-terminal nucleotide of tRNALys3 is positioned at a distance of one nucleotide unit away from the template in the active polymerization site of the enzyme.

p66/p51 and p51/p51 recombinant forms of reverse transcriptase from human immunodeficiency virus type 1--interactions with primer tRNA(Lys3), initiation of cDNA synthesis, and effect of inhibitors.

Human immunodeficiency virus type-1 (HIV-1) reverse transcriptase (RT) initiates reverse transcription from tRNA(Lys3). HIV-1 RT is a heterodimer consisting of two polypeptides, p66 and p51. In this work, the possible role of each subunit of RT in the interaction with its natural primer tRNA(Lys3) was studied. Two recombinant forms of HIV-1 RT, heterodimer p66/p51 and homodimer p51/p51, were used. Previously we have expressed and purified recombinant RT p51/p51 which possesses DNA polymerase activity [El Dirani-Diab, R., Andreola, M. L., Nevinsky, G., Tharaud, D., Barr, P. J., Litvak, S. & Tarrago-Litvak, L. (1992) FEBS Lett. 301, 23-28]. Here we show that HIV-1 RT p51/p51 displays certain properties very similar to the p66/p51 recombinant enzyme. The homodimer was able to anneal tRNA(Lys3) to the primer-binding site of the HIV-1 RNA template leading to a functional complex capable of synthesizing cDNA. Further, the p51/p51 enzyme behaved like RT p66/p51 concerning the strong inhibition produced by a non-nucleoside RT inhibitor. These data show that for RT p51/p51, one of the subunits of the homodimer adopts a conformation similar to the catalytic subunit (p66) present in the heterodimeric form. Part of this work was devoted to the study of the complex between the recombinant forms of HIV-1 RT and its primer tRNA. Each enzymatic form was cross-linked to tRNA(Lys3) in the presence of a platinum derivative, giving different ribonucleoprotein complexes of molecular masses higher than 100 kDa, suggesting that primer tRNA may interact with both subunits in the heterodimeric enzyme. After RNase A treatment of the complex RT p66/p51 x tRNA, the label was mainly found to migrate with the p66 subunit, although some cross-linking was also found associated to the p51 subunit. These results show that the p66 and p51 subunits of RT interact with tRNA(Lys3). Moreover, cross-linking of tRNA(Lys3) with HIV-1 RT p66/p51 in the presence of a DNA template containing the primer-binding-site sequence yielded an enzymatically active complex.

Interaction of tRNA-derivatives and oligonucleotide primers with AZT-resistant mutants of HIV-1 reverse transcriptase.

While the molecular basis of HIV-1 AZT resistance has been widely studied, a biochemical explanation of this process is not well known. No significant changes in the binding affinity of reverse transcriptase (RT) mutants for AZT-triphosphate has been found. Here we analyzed the interaction of wild type and AZT-resistant mutant forms of HIV-1 RT with different primers. Site-directed mutagenesis was used to introduce point mutations on the retroviral enzyme. Primers were either synthetic oligonucleotides or tRNA(Lys3) derivatives containing d(pT)n or r(pU)n at the 3' end. In all cases, determination of kinetic parameters was done in the presence or absence of compounds known to modify protein conformation, such as dimethyl sulfoxide (DMSO), urea, and Triton X-100. Although we found similar K(m) values for all RTs, there was generally an increase in the affinity when enzymes were tested in the presence of DMSO, urea, and Triton X-100. Then, we analyzed the nucleation and elongation steps of the polymerization process. The efficiency of formation of the first base pair was determined by measuring K(m1), the affinity between RT and the 3' terminal nucleotide of the primer. An important difference was found: in the presence of DMSO, urea, and Triton X-100, the K(m1) values for mutated enzymes were higher than those of wild type RTs. Thus, the presence of compounds able to change protein conformation led to a marked destabilization of the interaction of mutated RTs with the 3' terminal nucleotide of the primer. From these results, it can be hypothesized that resistance to AZT is not due to the direct influence of mutations on RT, but rather to conformational changes of the mutated RT in complex with the template-primer altering the ability of the enzyme to select or reject an incoming dNTP.

A second DNA polymerase activity in yeast mitochondria.

In eukaryotic cells, there is much evidence to indicate that the replication of the mitochondrial genome is carried out by a specific DNA polymerase named DNA polymerase gamma. In the yeast S. cerevisiae, a DNA polymerase gamma has been partially purified and the gene encoding the catalytic subunit identified. The characteristics of this enzyme are the same as those found in higher eukaryotes, except for the requirement for a higher magnesium concentration. During a purification procedure of yeast mitochondrial DNA polymerase, we have isolated a second DNA polymerase activity. Using different approaches ive have ruled out the possibility of nuclear contamination or a product of proteolysis. From its properties, this new DNA polymerase activity seems to be different from any yeast DNA polymerase. This new mitochondrial DNA polymerase activity provides evidence that the animal model of mitochondrial DNA replication cannot be generalized. The presence of two DNA polymerases in yeast mitochondria could reflect a different replication or repair mechanism.