Synthesis of esters and amides of 2-aryl-1-hydroxy-4-methyl-1H-imidazole-5-carboxylic acids and study of their antiviral activity against orthopoxviruses.

Smallpox was eradicated >40 years ago but it is not a reason to forget forever about orthopoxviruses pathogenic to humans. Though in 1980 the decision of WHO to cease vaccination against smallpox had seemed logical, it led to the decrease of cross immunity against other infections caused by orthopoxviruses. As a result, in 2022 the multi-country monkeypox outbreak becomes a topic of great concern. In spite of existing FDA-approved drugs for the treatment of such diseases, the search for new small-molecule orthopoxvirus inhibitors continues. In the course of this search a series of novel 2-aryl-1-hydroxyimidazole derivatives containing ester or carboxamide moieties in position 5 of heterocycle has been synthesized and tested for activity against Vaccinia virus in Vero cell culture. Some of the compounds under consideration revealed a selectivity index higher than that of the reference drug Cidofovir. The highest selectivity index SI = 919 was exhibited by ethyl 1-hydroxy-4-methyl-2-[4-(trifluoromethyl)phenyl]-1H-imidazole-5-carboxylate 1f. The most active compound also demonstrated inhibitory activity against the cowpox virus (SI = 20) and the ectromelia virus (SI = 46).

Estimation of Absolute Bioavailability of the Chemical Substance of the Anti-Smallpox Preparation NIOCH-14 in Mice.

We compared absolute bioavailability of the chemical substance of the anti-smallpox preparation NIOCH-14 and chemical compound ST-246 active against orthopoxviruses after oral administration to mice in doses of 10 and 50 µg/g and intravenous administration to mice in a dose of 2 µg/g body weight. The absolute bioavailability of NIOCH-14 is comparable with the absolute bioavailability of ST-246.

[Evaluation of therapeutic-prophylactic effectiveness of chemical compound NIOC-14 against ectromelia virus in vivo].

AIM: Study pharmacodynamic parameters of anti-viral effectiveness of a chemical compound NIOC-14 in experiments in mice infected with ectromelia virus (EV). MATERIALS AND METHODS: EV (K-1 strain) was obtained from the State Collection of Viral Infections and Rickettsioses Causative Agents of the State Scientific Centre of Virology and Biotechnology "Vector". Outbred ICR mice were intranasally infected with EV at a dose of 10 LD50 per animal (10 x 50% lethal doses/animal) and per orally received NIOC-14 or ST-246 as a positive control. Chemical compound NIOC-14 (7-[N'-(4-trifluoromethylbenzoyl)-hidrazincarbonyl]-tricyclo[3.2.2.0(2,4)]non-8-en-6-carbonic acid) was synthesized in Novosibirsk Institute of Organic Chemistry (NIOC). Anti-pox preparation ST-246, developed by SIGA Technologies Inc. (USA), was synthesized in NIOC using the technique described by the authors. RESULTS: 50% effective doses against EV in vivo were shown not to differ significantly between the preparations NIOC-14 (3.59 µg/g mouse mass) and ST-246 (5.08 µg/g mouse mass). During determination of therapeutic window, administration of NIOC-14 to mice 1 day or 1 hour before EV infection, as well as 1, 2 and 4 days after EV infection and then for 9 days was found to ensure 100% animal survival. Administration of NIOC-14 as well as ST-246 resulted in the decrease relative to control of EV titers in lungs, nasal cavity, brains, liver, spleen, kidneys and pancreas. CONCLUSION: Anti-viral effectiveness of NIOC-14 against EV in vivo was thus comparable by all the studied pharmacodynamic parameters with anti-viral activity of anti-pox-virus preparation ST-246.

[A comparative study of the antiviral activity of chemical compounds concerning the orthopoxviruses experiments in vivo].

In the experiments using intranasal (i/n) infection of mice with the ectromelia virus (EV) in a dose 10 LD50/head (10 x 50% lethal doselhead) or with the monkaypox virus (MPXV) in a dose 10 ID50/head (10 x 50% infective dose/ head) it was demonstrated that the antiviral efficiency of chemical compounds - the condensed derivatives of pyrrolidin-2,5-dion, as well as their predecessors and the nearest analogues, synthesized in Novosibirsk Institute of Organic Chemistry of the Siberian Branch of the Russian Academy of Sciences (NIOCH SB RAS) was observed. As a positive control we used the antipoxvirus chemical preparation ST-246 available from SIGA Technologies Inc. (USA), synthesized in NIOCH SB RAS by the technique suggested by the authors. It was demonstrated that the compound NIOCH-14 (7-[N'-(4-Trifluoromethylbenzoil)-hydrazidecarbonil]-tricyclo[3.2.2.02,4]non-8-en-6-carbonic acid) possessed comparable with ST-246 antiviral activity concerning EV and MPXV on all indicators used. Therefore, at infection of mice with EV (strain K-1) and peroral administration of NIOCH-14 and ST-246 in a dose 50 mkg/g of mouse weight (12-14 g) within 10 days the survival rate and average life expectancy of mice authentically exceeded the control levels. EV titers in lungs through 6 days after infection in the same groups were lower than in the control. In addition to that, after 7 days of infection of mice with MPXV (strain V79-1-005) and daily peroral administration of NIOCH-14 and ST-246 in a dose 60 mkg/g of mouse weight (9-11 g) authentic decrease in a part of infected animals and MPXV titers in lungs was observed.

[Construction of combinatorial immune library of single chain human antibodies to orthopoxviruses and selection from this library antibodies to recombinant protein prA30L of variola virus].

A combinatorial immune library of human single-chain antibody fragments (scFv) was constructed on the base of genes encoding variable domains of heavy and light chains of immunoglobulins cloned from the lymphocytes of four vaccinia virus (VACV) vaccinated donors. The size of the library was 3 x 10(7) independent clones. After the library was enriched with the clones producing scFv against recombinant analogue of variola virus surface protein prA30L, a panel of unique antibodies specific to both prA30L and VACV was selected from the library. A plaque reduction neutralization test was performed for all selected antibodies and two antibodies were shown to be able to neutralize plaque formation of VACV in Vero E6 cells monolayer. Binding specificities of these antibodies were confirmed using ELISA and Western blot analysis. To determine the amino acid sequences of neutralizing antibodies their genes were sequenced.

Phage antibodies from combinatorial library neutralize vaccinia virus.

The library of human scFv antibodies displayed on the surface of bacteriophages was panned against Vaccinia virus (VACV), strain Elstree. 75% binding with Vaccinia virus. 5 clones were characterized for their binding with VACV and their ability to neutralize VACV in plaque reduction neutralization test (PRNT). Antibodies from the clones were obtained as soluble individual molecules and their binding activities were confirmed in ELISA.

[Production and characterization of a panel of monoclonal antibodies to Toxoplasma gondii antigens]. / Poluchenie i kharakteristika paneli monoklonal'nykh antitel k antigenam Toxoplasma gondii.

A representative collection was obtained containing 68 monoclonal antibodies (MAB) to Toxoplasma gondii antigens, which was characterized by the binding with the below fractions of tochizoites in the immune-enzyme assay (IEA) and immunoblotting (IB): membrane (MEM), somatic (water-soluble, SOM) and excretory-secretory (ES). Most of MABs were produced to MEM antigens (43), 6 MABs reacted with the somatic fraction, and 3 MABs reacted with both fractions. Two MABs to ES antigen were detected in the latter group. An analysis of MABs in concurrent IEA and IB revealed the immune-dominant proteins of the MEM and SOM fractions of antibodies to T. gondii tochizoites (p30 and p27, respectively). The presence of 2 non-overlapping antigenic determinants was shown for p30. Further research would detect MABs that could be used in the diagnosis of toxoplasmosis.

[A study of neutralizing activity and cross-reactivity of monoclonal antibodies to ectromelia virus with orthopoxviruses pathogenic for man]. / Neitralizuiushchaia aktivnost' i perekrestnoe reagirovanie monoklonal'nykh antitel k virusu éktromelii s patogennymi dlia cheloveka ortopoksvirusami.

An extensive collection of 125 rat hybridomas secreting monoclonal antibodies (Mabs) to ectromelia virus (EV) polypeptide (Poxviridae family, Orhtopoxvirus genus) was set up. A significant portion of Mabs (37 types) recognized epitopes of the 14 kDa polypeptide as well as the 37 and 35 kDa polypeptides. However, a majority of Mabs interacted with conformation-dependent epitopes, which were destroyed in immunoprecipitation. One hundred and thirteen of Mabs cross-interacted with antigenic determinants of vaccinia viruses (VV), cowpox virus (CPV) and smallpox virus (SPV); only 12 of them were found to be specific to EV. The Mabs antigenic activity was tested for 46 types of cross-reactivity Mabs in VV neutralization on Vero cells. Only the 112H12, 113D5, 113F8, 122H9 and 125G9 Mabs, which were specific to the kDa 14 polypeptide (gene A30L EV), had the neutralizing activity. The 122H9 and 125G9 Mabs were able to neutralize SPV. Therefore, it can be assumed that the 14 kDa polypeptide carries, on its surface, cross-reactivity neutralizing epitopes typical of orthopoxviruses.

[Detection of antiviral activity of monoclonal antibodies, specific to Marburg virus proteins]. / Vyiavlenie protivovirusnoi aktivnosti monoklonal'nykh antitel, spetsifichnykh k belkam virusa Marburg.

Monoclonal antibodies (MAbs) specific to Marburg virus (MBG), Popp strain, have been previously produced and characterized by indirect ELISA. Protein specificity of MAbs was determined by immunoblotting with SDS-PAGE proteins of MBG: one to NP, four to VP40, and protein specificity of one antibody was not detected. The effect of MAb binding to protein epitopes on viral functions was investigated in vitro and in vivo. None of antibodies neutralized the virus in the neutralization test in vitro, but MAb 5G9.G11 and 5G8.H5 specific to MBG VP40 protein were active in antibody-dependent complement mediated lysis of virus-infected cells. In vivo these antibodies (5G9.G11 and 5G8.H5) protected guinea pigs from lethal MBG infection after passive inoculation. Studies of biological activity and analysis of epitope specificity of MAb-antiVP40 by competitive ELISA showed that 2 of 7 epitopes of VP40 protein of MBG induce the production of protective antibodies. Hence, MAbs 5G9.G11 and 5G8.H5 reacting with MBG VP40 protein caused lysis of virus infected cells in the presence of the complement in vitro and protected guinea pigs from MBG infection by passive inoculation.

[Survival of Marburg virus infectivity on contaminated surfaces and in aerosols]. / Sokhranenie infektsionnosti virusa Marburg na kontaminirovannykh poverkhnostiakh i v aérozole.

Marburg virus was shown to survive for up to 4-5 days on contaminated surfaces. In aerosol it was not stable, the specific rate of its inactivation being 0.05 min-1. This brought the authors to a conclusion that a relatively close contact is needed for virus transmission from man to man, although the possibility of aerosol transmission of the infection may be appreciably increased in case of the hemorrhagic syndrome with a high level of viremia.

[Investigation of the protein composition and immunochemical properties of Toxoplasma gondii excretory and secretory antigen]. / Izuchenie belkovogo sostava i immunokhimicheskikh svoistv ékskretorno-sekretornogo antigena Toxoplasma gondii.

The major proteins of T. gondii excretory and secretory antigens (ESA) obtained during cultivation of tachyzoites by using cultured Vero cells were shown to have molecular weights of 79, 70, 57, 48, 36, and 29 kD. ESA and somatic antigen immunoblotting demonstrated that there were noticeable differences in the immunoactive proteins of these antigens. The antibodies of the sera of patients with toxoplasmosis mainly interacted with ESA proteins having molecular weights of 79, 70, 57, 48, 36, and 29 kD, 57-kD ESA protein antibodies being present on the immunoblots of all the tested sera. When ESA was used as an antigen during enzyme immunoassay, it showed a high sensitivity in the detection of IgM antigens in congenital toxoplasmosis. At the same time, ESA identified the antibodies of this class in the sera of healthy donors much infrequently than somatic antigen (p < 0.05).

[Composition of circulating immune complexes in acute toxoplasmosis]. / Izuchenie sostava tsirkuliruiushchikh immunnykh kompleksov pri ostrom toksoplazmoze.

The circulating immune complexes (CIC) that form in the hot just in early Toxoplasma gondii invasion can be present in the blood bed for a while. At the same time, the data on the antigenic composition of CIC in toxoplasmosis are fragmentary and rather contradictory. The investigation used enzyme immunoassay (EIA) to detect specific CIC that contain antigens to T. gondii tachyzoites in the sera of different populations and studied their antigenic composition by immunoblotting after 2-6% polyethylene glycol 6000-induced deposition. Examining 464 sera from groups of individuals with varying-stage T. gondii invasion indicated CIC in each, but showing their different frequency. CIC were virtually present in all sera from children who had been diagnosed as having congenital toxoplasmosis. In groups of seropositive pregnant women, CIC detection rates were noticeably higher in the samples showing both IgG and IgM antibodies (40.2 and 66.4%, respectively). CIC were also revealed in 9.8% of the seronegative blood donors; however, immunoblotting failed to confirm that they had no components that specifically reacted with T. gondii tachyzoite antigen antibodies. There were some differences in the composition of CIC in the serum yielding positive results in both EIA and immunoblotting. The serum CIC from pregnant women that exhibited only IgG antibodies contained mainly T. gondii antigens having molecular weights of 67 and 30 kD. The serum CIC from children with congenital toxoplasmosis and from pregnant women with serologically detected IgM antibodies to Toxoplasma antigens were found to contain 55-58-, 48-, 44-, 38-, 30-, and 26-kD components. The same molecular weight proteins were detected by electrophoretic studies of Toxoplasma excretory-secretory antigen (ESA). Comparing the findings suggests that in acute toxoplasmosis, the circulating complexes mainly contain ESA of the tachyzoites which appear in human blood just at the onset of invasion. Thus, this study demonstrates that specifically CIC are detectable in the sera of individuals infected with T. gondii and their antigenic composition varies with the stage of disease. In the authors' opinion, the detection of specific CIC and the determination of their antigenic composition may be serve an additional test in diagnosing acute toxoplasmosis.

[The seroepidemiology of toxocariasis in an opisthorchiasis focus in the western Siberian region]. / Seroepidemiologiia toksokaroza v ochage opistorkhoza zapadno-sibirskogo regiona.

Seroprevalence to Toxocara antigens was studied among Novosibirsk inhabitants and a focus of toxocariasis was found in the southern regions of west Siberia. Analyzing the sera of opisthorchiasis patients revealed antibodies to Toxocara antigens, with high titers (1:800 or more) in 1.80% of cases. Immunoblotting of these sera and those from patients with toxocariasis and opisthorchiasis, which were seropositive in one of the above helminths showed that there were mixed human infections with Toxocara and Opisthorchis in this area.

[The detection of antibodies to the trophozoite antigens of Lamblia by an immunoenzyme method]. / Vyiavlenie antitel k antigenam trofozoitov liamblii immunofermentnym metodom.

Whether purified antigens of Lamblia intestinalis trophozoites can be used to detect these antibodies by immunoassay. The drugs of immunodominant Lamblia antigens were prepared by anion-exchange chromatography of solubilized trophozoite components and they are mainly presented by proteins having molecular weights of 70, 56, and 49 kD. Immunoassay using these antigens revealed antibodies to Lamblia trophozoite antigens in sera of 87.6% of patients with lambliasis (its diagnosis was established on the basis of microscopic data on the duodenal content) and only in 16.2% of clinically healthy blood donors. Twenty six sera from patients with trichomoniasis having high levels of antibodies to trichomonad antigens were studied to evaluate the specificity of this method for detection of antibodies. It has been found that the proportion of subjects in this group who have also antibodies to Lamblia antigens does not greatly differ from that of healthy blood donors (19.2 and 16.2, respectively).

[An immunochemical study of the antigens from Toxoplasma gondii tachyzoites obtained in different cultivation systems]. / Immunokhimicheskoe izuchenie antigenov takhizoitov Toxoplasma gondii, poluchennykh v razlichnykh sistemakh kul'tivirovaniia.

The protein composition and immunochemical properties of Toxoplasma gondii tachyzoites cultured on Vero cells and on mice were studied. Despite the fact that the main components of both preparations were shown to be proteins with molecular weights of 47, 34, 24, and 22 kDa, Toxoplasma-infected human sera antibodies interact mainly with the antigens of 66, 62, 57, 42, 38, 37, 36, 31, and 24 kDa. Comparing efficiency of enzyme immunoassay using the antigens of the tachyzoites obtained in different culture systems showed that the preparation of cultured Vero cells is similar to those of peritoneal exudates from infected mice and may be successfully used for the detection of antitoxoplasma antibodies in the sera of infected subjects.

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.