[Antiviral properties of synthetic histidine derivatives containing membranotropic volumetrical carbocycles in their molecule against SARS-CoV-2 virus in vitro]

INTRODUCTION

Currently, low molecular-weight compounds are being developed as potential inhibitors of CoVs replication, targeting various stages of the replication cycle, such as major protease inhibitors and nucleoside analogs. Viroporins can be alternative protein targets. The aim of this study is to identify antiviral properties of histidine derivatives with cage substituents in relation to pandemic strain SARS-CoV-2 in vitro.

MATERIALS AND METHODS

Combination of histidine with aminoadamantane and boron cluster anion [B10H10]2 (compounds IIV) was carried out by classical peptide synthesis. Compound were identified by modern physicochemical methods. Antiviral properties were studied in vitro on a monolayer of Vero E6 cells infected with SARS-CoV-2 (alpha strain) with simultaneous administration of compounds and virus.

RESULTS

Derivatives of amino acid histidine with carbocycles and boron cluster were synthesized and their antiviral activity against SARS-CoV-2 was studied in vitro. Histidine derivatives with carbocycles and [B10H10]2 have the ability to suppress virus replication. The solubility of substances in aqueous media can be increased due to formation of hydrochloride or sodium salt.

DISCUSSION

2HCl*H-His-Rim (I) showed some effect of suppressing replication of SARS-CoV-2 at a viral load of 100 doses and concentration 31.2 g/ml. This is explained by the weakly basic properties of compound I.

CONCLUSION

The presented synthetic compounds showed moderate antiviral activity against SARS-CoV-2. The obtained compounds can be used as model structures for creating new direct-acting drugs against modern strains of coronaviruses.

[Molecular epidemiological analysis of SARS-CoV-2 genovariants in Moscow and Moscow region]

INTRODUCTION

SARS-CoV-2, a severe acute respiratory illness virus that emerged in China in late 2019, continues to spread rapidly around the world, accumulating mutations and thus causing serious concern. Five virus variants of concern are currently known: Alpha (lineage B.1.1.7), Beta (lineage B.1.351), Gamma (lineage P.1), Delta (lineage B.1.617.2), and Omicron (lineage B.1.1.529). In this study, we conducted a molecular epidemiological analysis of the most prevalent genovariants in Moscow and the region. The aim of the study is to estimate the distribution of various variants of SARS-CoV-2 in Moscow city and the Moscow Region.

MATERIALS AND METHODS

227 SARS-CoV-2 sequences were used for analysis. Isolation of the SARS-CoV-2 virus was performed on Vero E6 cell culture. Sequencing was performed by the Sanger method. Bioinformatic analysis was carried out using software packages: MAFFT, IQ-TREE v1.6.12, jModelTest 2.1.7, Nextstrain, Auspice v2.34.

RESULTS

As a result of phylogenetic analysis, we have identified the main variants of the virus circulating in Russia that have been of concern throughout the existence of the pandemic, namely: variant B.1.1.7, which accounted for 30% (9/30), AY.122, which accounted for 16.7% (5/30), BA.1.1 with 20% (6/30) and B.1.1 with 33.3% (10/30). When examining Moscow samples for the presence of mutations in SARS-CoV-2 structural proteins of different genovariants, a significant percentage of the most common substitutions was recorded: S protein D614G (86.7%), P681H/R (63.3%), E protein T9I (20.0%); M protein I82T (30.0%), D3G (20.0%), Q19E (20.0%) and finally N protein R203K/M (90.0%), G204R/P (73.3 %).

CONCLUSION

The study of the frequency and impact of mutations, as well as the analysis of the predominant variants of the virus are important for the development and improvement of vaccines for the prevention of COVID-19. Therefore, ongoing molecular epidemiological studies are needed, as these data provide important information about changes in the genome of circulating SARS-CoV-2 variants.

[High Heterogeneity of Virus-Neutralizing and RBD-Binding Activities of COVID-19 Convalescent Sera]

The parameters of the humoral response are an important immunological characteristic of donors who recovered from COVID-19 and vaccinated individuals. Analysis of the level of virus-binding antibodies has become widespread. The most accurate predictor of effective immune protection against symptomatic SARS-CoV-2 infection is the activity of virus-neutralizing antibodies. We determined virus-neutralizing activities in plasma samples of individuals (n = 111) who had COVID-19 from April to September 2020. Three independent methods were used: conventional with live virus, with virus-like particles pseudotyped with spike protein, and a surrogate virus-neutralization test (cVNT, pVNT and sVNT, respectively). For comparison, the levels of IgG, IgA and IgM antibodies against the receptor-binding domain of the SARS-CoV-2 spike protein were also evaluated. The levels of virus-binding as well as virus-neutralizing antibodies in cVNT and pVNT showed high heterogeneity. A comparison of cVNT and pVNT results showed a high correlation, sVNT results also correlated well with both cVNt and pVNT. To the greatest extent, the level of IgG antibodies correlated with the results of cVNT, pVNT and sVNT. These results can be used in the selection of plasmas that are best suited for transfusion and treatment of acute COVID-19. In addition, data on the virus-neutralizing activity of plasma are important for the selection of potential donors, for the isolation of SARS-CoV-2-specific B-lymphocytes, in order to further generate monoclonal virus-neutralizing antibodies.

[Characteristics of imported cases of Dengue fever and hemorrhagic Dengue fever in 2009-2019]

INTRODUCTION

In Russia, the approved morbidity statistics system is represented by the International Classification of Diseases of the 10th revision (ICD-10). This classification provides two forms of dengue fever (DF): dengue fever (A90) and hemorrhagic dengue (A91). Official statistics on the ratio of forms of DF is not published in open sources and this lack of information about the real ratio of the forms of DF makes it difficult to objectively assess the factors that determine the severity of this disease.

THE AIM

compare the clinical and epidemiological features of dengue fever and hemorrhagic dengue fever in patients hospitalized in 2009-2019 to the City Infectious Clinical Hospital No. 1, Moscow.

MATERIALS AND METHODS

A retrospective cohort study. We analyzed the patient database and reviewed 391 medical records of patients with diagnosed dengue fever. We compared gender, age characteristics, travel geography including information about previous visits of patients to endemic regions and dengue virus serotype. To determine the primary and re-infection rate, an analysis of IgG for the dengue virus was carried out on days 1-5 of the disease. To compare indicators, 95% confidence intervals for proportions, medians, and interquartile ranges were calculated. The significance of differences between independent samples for assessing qualitative characteristics was carried out using the criteria χ2, the odds ratio. To assess the quantitative characteristics, the Mann-Whitney test was used. Differences were considered statistically significant at p ≤ 0.05.

RESULTS

The proportion of patients with dengue fever was 14.9% of all hospitalized with febrile illnesses that developed after international travel. Hemorrhagic dengue fever (DHF) was diagnosed in 15.7% of patients with dengue fever. DHF developed significantly more often in women, as well as in those who had history of repeated visits to endemic regions. However, DHF was also diagnosed in 10.9% of first-time travelers to tropical countries. We did not find significant differences in the rates of DHF development depending on age and dengue virus serotype. In a number of patients who had not previously traveled to endemic regions, IgG to the dengue virus were detected, which may indicate a previous infection with related flaviviruses.

CONCLUSION

It has been established that in the regions most visited by Russians, there is a circulation of all serotypes of the dengue virus with an annual change in the predominant serotype.

Isolation of a panel of ultra-potent human antibodies neutralizing SARS-CoV-2 and viral variants of concern

In the absence of virus-targeting small-molecule drugs approved for the treatment and prevention of COVID-19, broadening the repertoire of potent SARS-CoV-2-neutralizing antibodies represents an important area of research in response to the ongoing pandemic. Systematic analysis of such antibodies and their combinations can be particularly instrumental for identification of candidates that may prove resistant to the emerging viral escape variants. Here, we isolated a panel of 23 RBD-specific human monoclonal antibodies from the B cells of convalescent patients. A surprisingly large proportion of such antibodies displayed potent virus-neutralizing activity both in vitro and in vivo. Four of the isolated nAbs can be categorized as ultrapotent with an apparent IC100 below 16 ng/mL. We show that individual nAbs as well as dual combinations thereof retain activity against currently circulating SARS-CoV-2 variants of concern (such as B.1.1.7, B.1.351, B.1.617, and C.37), as well as against other viral variants. When used as a prophylactics or therapeutics, these nAbs could potently suppress viral replication and prevent lung pathology in SARS-CoV-2-infected hamsters. Our data contribute to the rational development of oligoclonal therapeutic nAb cocktails mitigating the risk of SARS-CoV-2 escape.

Development of pan-phlebovirus RT-PCR assay

This study reports the pan-phlebovirus assay capable of detecting both sandfly/mosquito- and tick-borne phleboviruses. Sensitivity and specificity of the assay was verified using a panel of arboviruses. The RT-PCR assay is simple and sensitive, and thus well suited for screening of field samples.

[L-Lysine-α-Oxidase in vitro Activity in Experiments on Models of Viruses Sindbis, Forest-Spring Encephalitis, Western Nile, Tyaginya and Dhori]

The antitumor effect of L-lysine-α-oxidase from the culture fluid of Trichoderma harzianum Rifai F-180 was investigated for the first time. The in vitro studies revealed its high activity on a model of the forest-spring encephalitis virus and no activity against the Sindbis, Western Nile, Tyaginya and Dhori viruses.

[Detection of rubella virus RNA in clinical material by real time polymerase chain reaction method]

AIM

Development of a reagent kit for detection of rubella virus RNA in clinical material by PCR-RT.

MATERIALS AND METHODS

During development and determination of analytical specificity and sensitivity DNA and RNA of 33 different microorganisms including 4 rubella strains were used. Comparison of analytical sensitivity of virological and molecular-biological methods was performed by using rubella virus strains Wistar RA 27/3, M-33, "Orlov", Judith. Evaluation of diagnostic informativity of rubella virus RNAisolation in various clinical material by PCR-RT method was performed in comparison with determination of virus specific serum antibodies by enzyme immunoassay.

RESULTS

A reagent kit for the detection of rubella virus RNA in clinical material by PCR-RT was developed. Analytical specificity was 100%, analytical sensitivity - 400 virus RNA copies per ml. Analytical sensitivity of the developed technique exceeds analytical sensitivity of the Vero E6 cell culture infection method in studies of rubella virus strains Wistar RA 27/3 and "Orlov" by 11g and 31g, and for M-33 and Judith strains is analogous. Diagnostic specificity is 100%. Diagnostic specificity for testing samples obtained within 5 days of rash onset: for peripheral blood sera - 20.9%, saliva - 92.5%, nasopharyngeal swabs - 70.1%, saliva and nasopharyngeal swabs - 97%. Positive and negative predictive values of the results were shown depending on the type of clinical material tested.

CONCLUSION

Application of reagent kit will allow to increase rubella diagnostics effectiveness at the early stages of infectious process development, timely and qualitatively perform differential diagnostics of exanthema diseases, support tactics of anti-epidemic regime.

[Use of RT-PCR and enzyme immunoassays for the specific diagnosis of Crimean hemorrhagic fever]

The objective of the investigation was to evaluate the efficiency of the RT-PCR kit "AmplySens CHF" produced by InterlabService of the Central Research Institute of Epidemiology and that of the ELISA kits made by the D. I. Ivanovsky Research Institute of Virology for the specific diagnosis of Crimean hemorrhagic fever (CHF). Examination of sera from CHF patients from the Astrakhan Region showed that positive RT-PCR results were observed in 95.2 and 37.5% on days 4-8 and 9-13 after disease onset, respectively; but they were absent on days 13-17. Positive ELISA-IgM results were found in 93% on disease days 6 to 16. A high percentage (78.9%) of positive IgG samples was seen only on days 9-16. Thus, RT-PCR has a marked efficiency in diagnosing CHF until day 8 of illness while ELISA-IgM has it on day 8 or later. ELISA-IgG can be considered to be a confirming rather than compulsory test. The findings suggest that the RT-PCR kit "AmplySens CHF" produced by InterlabService of the Central Research Institute of Epidemiology and that of the ELISA kits made by the D. I. Ivanovsky Research Institute of Virology have a pronounced sensitivity and specificity and a high efficiency when concurrently used to verify CHF in patients.

[A case of Crimean-Congo hemorrhagic fever in the Anapa District, Krasnodar Territory]

The paper gives information on the first case of Crimean-Congo hemorrhagic fever detected in a female resident of the Anapa District, Krasnodar Territory, in 2005 in the past 57 years.

[PHOSPHAN microplate technology-based microarray for the determination of IgG antibodies against West Nile and Crimean-Congo hemorrhagic fever viruses]

The paper demonstrates it possible to work out a phosphorescence analysis (PHOSPHAN) microplate technology-based microarray for concurrently examining human sera and detection of their specific IgG antibodies against two heterological West Nile and Crimean-Congo hemorrhagic fever viruses. The sensitivity and specificity of the microarray were comparable with those of enzyme immunoassay with separate sample testing. The advantages of PHOSPHAN were associated with the microplate format of an immunoassay and its enhanced multiplexity, which may contribute to the lower cost of clinical sample testing.

[Results of examination of healthy residents in the southern region of Russia and patients feverish to pappataci fever virus antibodies]

Sera from patients with acute seasonal fevers and apparently healthy individuals living in the Astrakhan Region, Krasnodar Territory, or Rostov Region were examined in two modifications of enzyme immunoassay for detection of IgM and IgG antibodies to Neapolitan and Sicilian pappataci fever viruses. IgM antibodies to Sicilian pappataci fever virus were detected in a patient from the Volodarsky District, Astrakhan Region, who had been admitted for the unverified diagnosis of Q fever. A donor residing in the Novorossiysk District, Krasnodar Territory, was found to have IgA antibodies to Neapolitan pappataci fever virus. The findings show it expedient to conduct further investigations of the serodiagnosis and seroepidemiology of pappataci fevers in the southern Russian region where mosquitoes of the genus Phlebotomus inhabit.

[In vitro activity of Russian ribavirin on the models of Crimean-Congo hemorrhagic fever virus, Rift Valley fever virus, and Tahyna and Dhori viruses]

The high activity of ribavirin made by effective biotechnology in Russia was established in in vitro experiments using the models Crimean-Congo hemorrhagic fever virus, Rift Valley fever virus, and Tahyna and Dhori viruses, which suggests that it is promising in using the drug in the treatment of infection with these viruses.

[ELISA and PCR test systems used to detect Crimean-Congo hemorrhagic fever virus]

Studying the sensitivity and specificity of enzyme-linked immunosorbent assay (ELISA) for the indication of Crimean-Congo hemorrhagic fever (CCHF) virus antigens and those of reverse transcription and polymerase chain reaction (RT-PCR) for the detection of CCHF virus RNA, and those of a intercerebral infection method in newborn albino mice systems for the determination of viral infectious activity established that the sensitivity of ELISA was 1-2 orders of magnitude less than that of RP-PCR. The latter proved to be better in studying the sera sampled from patients with CCHF. The results of studying the samples of H. marginatum ticks, the CCHF virus vectors by ELISA and RT-PCR were similar.

[Morphological and immunohistochemical changes in tissues of the lung, myocardium and kidney in experimental West Nile fever]

An experimental infection of mice with West Nile virus (WNV) showed pronounced dystrophic changes in tissues of the kidneys and myocardium as well as expression of WNV antigens in cells of the lungs, kidneys and myocardium, which can denote tropism of WNV to tissues of the lungs, kidneys and myocardium.

[Hepatotropic action of the virus of West Nile fever]

An experimental infection of mice with West Nile Virus (WNFV) showed pronounced dystrophic changes in the hepatic parenchyma and expression of WNV antigens in the endothelium of hepatic capillaries and in hepatocyte cytoplasm, which testifies to the tropic action of WNFV to hepatic tissue.

[ West Nile fever among residents of the Astrakhan region in 2002]

Thirty-three persons infected with West Nile fever were detected in 2002 in the Astrakhan Region; the diagnosis was confirmed serologically and the maximal number of the infected was registered in August, same year. The indices of the specific humoral immunity varied from 3.3% to 27.1%. A monitoring determined the highest infection risk among the residents of the Volga middle delta.

Morphofunctional characteristics of antigen-presenting cells in lymph node in mice with experimental West Nile fever

Pronounced transformation of cells in mesenteric lymph nodes, mainly in the thymus-independent zone and sinuses, was detected in albino mice experimentally infected with West Nile fever (strain 986). Maximum antigen-presenting activity was exhibited by activated macrophages, minimum activity--by dendritic cells of lymphoid follicles.

[Specific antibodies in convalescents after West Nile fever]

Blood serum samples were obtained from patients with West Nile fever (WNF) from the city of Volgograd and its region within the disease weeks 1-3 (July-October 1999), month 6-7 (May_June 2000) and month 12-18 (May-June 2001) after the disease onset. In the sera of 40 patients examined 6-7 months after the disease onset IgM-antibodies to WNF virus were absent (dilution 1:50), IgG ones were detected in 35 patients (87.5%). 18 months after the disease IgG-antibodies were identified in 23 of 26 convalescents (88.5%). The serum samples obtained in autumn 1999 and May-June 2000 contained antihemagglutinins to WNF virus for 6-7 months in all 18 patients. In May-June 2000 the sera were positive in 38 convalescents who had WNF in 1999.

[The study of immune structure of Astrakhan region population to West Nile virus in 1998 and 1999]

Immunostructure of the Astrakhan Region population to West Nile fever (WNF) was studied in the preepidemic period (1998) and after the outbreak (1999). Among the sera obtained in 1998, 63 (26.3%) were positive in neutralization reaction, 84 (27.1%) in enzyme immunoassay IgG and 20 (7.8%) in HAIR. IgM-antibodies were found in none of 142 samples. Overall number of donors having antibodies to WNF virus by three reactions reached 97 (31.6%). In the sera obtained in 1999, virus neutralizing antibodies were detected in 72(44.4%) cases, specific IgM antibodies detected by EIA_in 5(3.1%), IgG_in 44(27.1%), antihemagglutinins_in 11 (6.9%). The number of positive findings in 4 reactions in 1999 was 81(50.0%). The results of examination of the sera collected for two years (1998 and 1999) were the following: of 402 samples examined in NR positive were 135(33.6%), of 304 five (1.6%) were IgM positive, 128(27.1%) of 472 were IgG positive, and 31(7.4%) of 417 responded in HAIR. Overall index of humoral immunity for 2 years was 37.9% (in males and females 39.8 and 32.8%, respectively. In persons aged 20-29 years_36.9%, 50-59 years_42.9%. Thus, by 2-year results, antibodies to WNF virus occurred in 51.9% rural citizens and 35.0% city population.

[The isolation of Dhori viruses (Orthomyxoviridae, Thogotovirus) and Crimean-Congo hemorrhagic fever virus (Bunyaviridae, Nairovirus) from the hare (Lepus europaeus) and its ticks Hyalomma marginatum in the middle zone of the Volga delta, Astrakhan region, 2001]

In August, 2001, in the middle zone of the delta of the Volga River, the Astrakhan region, during investigation of the natural foci of West Nile fever and Crimean--Congo hemorrhagic fever (CCHF), the material from the hare (Lepus europaeus, Pallas, 1778 (Lagomorpha, Leporidae) and collected from it the ticks Hyalomna marginatum Koch 1844, was obtained. 4 strains of Dhori virus (Orthomyxoviridae, Thogotovirus) and 2 strains of CCHF virus (Bunyaviridae, Nairovirus) were isolated. This is the first isolation of Thogotovirus genus virus from the wild vertebrates. Considering the overlap of the Dhori virus and CCHF virus areas, similar ecology and the isolation both viruses from the same pool of the ticks, the necessity for the use of the test-system for indication of the viruses, differential diagnosis and accumulation of the data concerning the role of Dhori virus in the human and farm animals pathology is discussed.

[Analysis of new variants of West Nile fever virus]

The complete nucleotide sequences for 6 strains of the West Nile fever virus were determined. For the first time the complete nucleotide sequences of the Indian isolate and Krsn190 strain, that is the most far phylogenetically from all isolates known at present time were established. The scheme for separation of virus variants into 4 groups and criteria for determination the group to which the isolate belongs are suggested.

[Characteristics of humoral immunity to rubella virus in residents of Moscow in 1998-1999]

A total of 400 blood samples were collected from residents of Moscow in 1998-1999, 369 from adults aged mainly 19-31 years and from children aged 5-12 years. The mean incidence of antirubella antibody was 76.5%; the value varied in different age groups. The highest percentage of antibody detection was observed in men aged 19-25 years (91.8%) and the lowest in pregnant women aged 18-38 years (66-67%). Estimation of antihemagglutinin titers in international Units showed that antibody titer 1:40 and higher protected from infection; such titers were detected in 73.6% examinees. In pregnant women the level of immunological defense was very low (only 56%), which necessitates urgent vaccination of adolescent girls and young women. The results of EIA were compatible with the results of indirect hemagglutination test (IHAT), but EIA was much more sensitive in cases with low titers of IHAT.

[Genetic analysis of West Nile fever virus, isolated in the south of the Russian plain (Volgograd and Astrakhan regions) in 1999]

Two strains of West Nile virus, Vlg 27889 and Ast 986, were isolated from the brain of a dead man and from the blood of a patient, respectively, during an outbreak of serous meningitis and meningoencephalitis in July-September, 1999, in the Volgograd and Astrakhan regions. Analysis of parts of genome of the strains cloned from cell culture by reverse transcription and polymerase chain reaction demonstrated their identity and appurtenance to group I West Nile viruses.

[Virus-like particles as a source for obtaining antigens for diagnosing rubella]

Rubella diagnostic agents for hemagglutination inhibition (HI) and enzyme immunoassay (EIA) based on rubella virus-like particles (RVLP) have been developed. Noninfectious RVLPs containing three structural E1, E2, and C proteins were expressed in transfected CHO24S cell culture. HI titer in culture medium was 1:256. Tween-80 treatment and ether increased HI titer 4-6-fold and rendered the antigen higher stability. Immunogenic properties of RVLPs were similar to the native rubella virus in HI test with international reference human rubella serum and sera from convalescents after rubella. Serum of mice immunized with RVLP reacted similarly with RVLP antigens and native virus. Antigen for EIA from RVLP was prepared by concentrating RVLP from culture fluid and partial purification by ultracentrifugation. The results of human sera testing by HI and EIA with RVLP and native virus antigens coincided. RVLP are identical to antigenic structure of the virus, are stable and easily purified, and can therefore be used for commercial production of HI and EIA antigens.

[Isolation of the West Nile Fever virus from human patients during an epidemic outbreak in the Volgograd and Astrakhan regions]

Two strains of West Nile virus LEIV 27889 Vig and Ast 986 were isolated from the brain of a dead subject and from the blood of a patient, respectively, during an outbreak of serous meningitis and meningoencephalitis in July-September, 1999, in the Volgograd region, Krasnodar territory, and Astrakhan region. These strains reacted with convalescent sera in hemagglutination inhibition test, which proves their etiological role in this outbreak.

[Epidemic outbreak of meningitis and meningoencephalitis, caused by West Nile virus, in the Krasnodar territory and Volgograd region (preliminary report)]

Sera from 102 inpatients from the Volgograd region (64) and Krasnodar region (38) were tested for antibodies to West Nile (WN) virus in hemagglutination inhibition (HI) test and for IgM and IgG antibodies in enzyme immunoassay (EIA). Diseases etiologically associated with WN virus were diagnosed in 81 patients: in 50 out of 64 in the Volgograd region and in 31 out of 38 in the Krasnodar region, which makes 79.4%. Specificity of antibodies to WN virus was confirmed in HI and EIA with WN antigens, related flaviviruses (Japanese encephalitis and yellow fever), and Sindbis alfavirus. A considerable number and the incidence of WN infection suggest that an epidemic caused by WN virus occurred in the Krasnodar and Volgograd regions in summer 1999.

[Identification of California serogroup viruses (Bunyaviridae, Bunyavirus) using monoclonal antibodies to Inkoo virus]

Five types of monoclonal antibodies to inkoo virus were used to detect antigenic relationships between 12 Inkoo-like strains and the prototype Inkoo virus strain. Eight strains were found antigenically very close or identical to Inkoo virus, and the rest 4 are probably original variants (viruses) of California serogroup.

[Preparation and use of monoclonal antibodies to the Inkoo virus (Bunyaviridae, Bunyavirus) for differentiating between California serogroup viruses]

Five types of monoclonal antibodies (Mab) to Inkoo virus were obtained. The direction of Mabs to virus proteins was determined and reactions of Mabs with other California group viruses studied by the fluorescent antibody method.