We present the single-cell transcriptomic analysis of peripheral blood mononuclear cells (PBMC) from individuals during acute HIV-1 infection caused by viral strains circulating in Russia and the Former Soviet Union (FSU) countries. Using 10x Genomics single-cell RNA sequencing (scRNA-seq) on the Illumina NextSeq 550 platform, we have analyzed scRNA-seq data from three treatment-naive patients (viral load > 1 × 106 copies/mL, estimated infection duration ≤ 4 weeks) and three healthy donors. Data integration (Seurat, Harmony), automated cell-type annotation (CellTypist), and GeneOntology (GO) enrichment analysis for highly expressed and low-expressed genes revealed a profound reorganization of transcriptional programs across key immune populations, including memory CD4+ and CD8+ T cells, non-classical monocytes and natural killer cells (NK-cells). We observed signatures of hyperactivation of pro-inflammatory pathways (NF-kB, TNF, and type I/II interferon signaling), upregulation of genes associated with cellular migration (CXCR4, CCR7) and metabolic adaptation (oxidative phosphorylation components), alongside a mixed pro- and anti-apoptotic expression profile. Notably, our data pointed to a pronounced dysregulation of the TGF-β and mTOR signaling cascades, disrupted intercellular communication networks—particularly between cytotoxic cells and their regulators—altered expression of genes implicated in disease progression (OLR1, SERPINB2, COPS9) and viral persistence control (NEAT1, NAF1). This work provides an initial single-cell transcriptional atlas characterizing early immune responses to HIV-1 sub-subtypes A6 and CRF63_02A6, the predominant drivers of the HIV epidemic across the FSU region.

The Colorado potato beetle is one of the most devastating potato pests in the world. However, its viral pathogens, which might have potential in pest control, have remained unexplored. With high-throughput sequencing of Colorado potato beetle samples derived from prepupal larvae which died from an unknown infection, we have identified two previously unknown RNA viruses and assembled their nearly complete genome sequences. The subsequent genetic and phylogenetic analysis demonstrated that the viruses, tentatively named Leptinotarsa iflavirus 1 and Leptinotarsa solinvi-like virus 1, are the novel representatives of the Iflaviridae and Solinviviridae families, respectively. To the best of our knowledge, these are the first sequencing-confirmed insect viruses derived from Colorado potato beetle samples. We propose that Leptinotarsa iflavirus 1 may be associated with a lethal disease in the Colorado potato beetle.

Introduction: The atmosphere of Novosibirsk is characterized by increased levels of suspended particles, a significant part of which are bioaerosols. The latter include bacteria and fungi that can induce infectious diseases, allergies, and other negative responses in the population. Yet, the microbiota of ambient air of Novosibirsk and the region is poorly studied. Objective: To determine the concentration and composition of microorganisms in atmospheric aerosols of Novosibirsk and the region isolated in spring/summer 2023 and to test the microbial isolates for pathogenicity. Materials and methods: To isolate microorganisms from ambient aerosols, air was filtered applying Sartorius reinforced Teflon membrane filters and Hopar compressors. Their desorption from the filters was carried out by shaking in a physiological solution on a rocker and vortex followed by sowing the resulting suspensions onto nutrient media. We determined pathogenic signs by the presence of aggression enzymes and sensitivity of microbial isolates to antibiotics by the disk diffusion method. Sequencing of the 16S rRNA gene was performed by Sanger method; full genome sequencing was performed using the NextSeq 550 system. Results: During the study of the microbiota of atmospheric aerosols in Novosibirsk and the region in spring/summer 2023, fungi, spore-forming and non-spore-forming bacteria, both saprotrophic and pathogenic, were isolated with concentrations in the aerosol ranging from 100 to 8×103 CFU/m3, including multiple drug resistant ones. Fungi were generally represented by opportunistic and allergenic species of the genera Aspergillus, Alternaria, Cladosporium, Aureobasidium, and Penicillium, while bacteria – by a large variety of spore-forming and non-spore-forming bacterial species. Based on the results of analyzing phenotypic traits and the 16S rRNA gene sequencing, 119 bacterial isolates were identified. Full genome sequencing analysis and pathogenicity testing by secretion of catalase, hemolysins, lecithinase, lipase, plasma coagulase, alkaline phosphatase, gelatinase were performed for 49 of them along with testing for antibiotic resistance. We identified twenty-nine strains belonging to B. safensis, B. cereus, P. megaterium, B. mycoides, P. agglomerans, S. equorum, A. lwoffii, and a number of others with 5 to 7 positive reactions out of 9 in pathogenicity testing, capable of causing infectious diseases. Eleven strains showed resistance to 4 to 7 antibiotics, enabling their classification as multidrug-resistant. Conclusions: Detection of fungi and bacteria, which are among the most dangerous pathogens with multiple antimicrobial resistance, prove the necessity of constant control of the composition of bioaerosols in the urban environment.

Extensive spread of tick-borne diseases poses a significant problem for public health and the health of the population living in endemic areas.The aim of the study was to search, analyze genetic material and identify new viral agents of the Phenuiviridae family in taiga ticks collected in Asian regions of Russia using the method of high throughput sequencing.Materials and methods. The study involved 1460 taiga ticks collected in suburban areas of the Tomsk, Yekaterinburg and Primorsky Territory. The genetic material isolated from ticks was sequenced using Illumina technology followed by phylogenetic analysis.Results and discussion. Analysis of the sequencing results made it possible to detect extended nucleotide sequences of the L-gene fragment characteristic of the Phenuiviridae family viruses. We were able to identify 20 nucleotide sequences the length of 250 bp on average in homogenates of Ixodes persulcatus ticks. Eighteen isolates have been identified as members of the genus Uukuvirus and two isolates have been assigned to the genus Phlebovirus, Phenuiviridae family. Phylogenetic analysis has shown that all isolates of the genus Uukuvirus fall under the cluster of Tacheng tick virus 2 belonging to the species Tacheng uukuvirus. They form a separate phylogenetic group which is closely related to two Romanian variants of 2019. Tacheng tick virus 2 was detected in all three surveyed regions of the Asian part of Russia. Two Tomsk isolates of phlebovirus were classified as Sara tick phlebovirus and they clustered with two isolates of phleboviruses from Karelia. Thus, the genetic material of Tacheng tick virus 2 and Sara tick phlebovirus belonging to two genera of the family Phenuiviridae was found in I. persulcatus ticks collected in three geographically different regions of the Asian part of Russia.

The Colorado potato beetle is one of the most devastating potato pests widespread in the world. However, its viral pathogens remain highly unexplored. Here using SISPA high-throughput sequencing of Colorado potato beetle (CPB) samples derived from prepupal larvae that died from an unknown infection, we have identified two previously unknown viruses and assembled their full-length genomic sequences. The subsequent genetic and phylogenetic analysis of the obtained sequences demonstrated that the isolated viruses, named Leptinotarsa iflavirus 1 and Leptinotarsa solinvi-like virus 1 , are the novel representatives of Iflaviridae and Solinviviridae viral families, respectively. To the best of our knowledge, these are the first sequencing-confirmed insect viruses derived directly from CPB samples. And we also propose that Leptinotarsa iflavirus 1 may be associated with lethal disease in CPB.

A change in biological properties of the SARS-CoV-2 virus can enhance its transmissibility and virulence, complicate the disease course, and reduce the effectiveness of anti-viral therapy and vaccination. We have studied 16 genetic lineages of the Omicron variant. The viral reproduction course was analyzed based on plaque morphology in the agar layer and the maximum titer in Vero E6 cells. BALB/c mice and Syrian hamsters were used as animal models. Viral load and infectious SARS-CoV-2 titer were determined in the nasal tissue and lungs. The severity of infectious process was assessed using histological methods. An increased plug size was observed in CH.1.1 and BQ.1.2.1 strains after six passages. This was due to substitutions D614G, H655Y, and N764K in the coronavirus S protein. The same changes in gene variants Gamma and BA.1 were caused by the substitution R682W, which is not present in lineages CH.1.1 and BQ.1.2.1. A similar substitution, namely R682P, was observed in the BA.5.1 strain. We characterized BA.1 (as a reference), BA.5.2, and XBB.3 strains in vivo as representatives of the main circulating genetic lineages. For the BA.1 strain, ID50 was 1.3 and 14 TCD50 in Syrian hamsters and BALB/c mice, respectively. An insignificant increase in the BA.5.2 virulence compared to that of BA.1 was noted (ID50 was 07. and 10 TCD50, respectively). The XBB.3 pathogenicity in laboratory animals is similar to that of BA.1 (ID50 was 1.8 and 15 TCD50, respectively). Experiments showed a consistent decrease in the virulence of Omicron strains compared to previously circulating SARS-CoV-2 variants. A co-evolutionary change in amino acid sequences, affecting the conformation of the coronavirus S protein and its surface epitopes in representatives of different genetic lineages, was noted. The emergence of potential proteolysis sites and alterations of the furin cleavage site have been observed in numerous Omicron coronavirus variants.

The spread of the disease caused by monkeypox virus (MPox) since 2022 has shown the urgency of developing countermeasures. The development of modern methods of clinical laboratory diagnostics of MPox contributes to this. Enzyme-linked immunosorbent assay (ELISA) is an accessible and sensitive platform for developing diagnostic tools. Detection of MPox antigens using ELISA kits based on monoclonal antibodies (MAbs) is promising due to the quick time of analysis and minimal requirements for sample preparation. We have developed and deposited two strains of Escherichia coli that produce recombinant proteins. Mice were immunized with the AgPOX protein, which contains unique antigenic sequences of MPox. The Trx + A29 protein for selecting MAb producers includes the original amino acid sequence A29L. The absence of antibody crossover to Trx protein and native preparations of variola virus and vaccinia virus tested by ELISA. As a result of hybridization of splenocytes from immunized mice, MAb producers were obtained. Fifteen MAb-producing hybridomas were selected based on ELISA results with three specific MPox antigens and three nonspecific ones. Three hybridomas were selected for deposit according to the productivity criteria. The possibility of detection by means of its MAbs of the native MPox antigen at various concentrations was tested and method sensitivity was determined. The MAbs a-A29L_MPoxV of three hybridomas detected the native antigen MPox at a concentration of 102 PFU/mL. It is likely that the method is even more sensitive when selecting analysis conditions. Based on labeled MAbs a-A29L_MPoxV, it is possible to develop a sensitive and specific indirect two-step ELISA kit for immunodiagnostics of MPox.

The Colorado potato beetle (CPB) is one of the most serious insect pests due to its high ecological plasticity and ability to rapidly develop resistance to insecticides. The use of biological insecticides based on viruses is a promising approach to control insect pests, but the information on viruses which infect leaf feeding beetles is scarce. We performed a metagenomic analysis of 297 CPB genomic and transcriptomic samples from the public National Center for Biotechnology Information Sequence Read Archive (NCBI SRA) database. The reads that were not aligned to the reference genome were assembled with metaSPAdes, and 13314 selected contigs were analyzed with BLAST tools. The contigs and non-aligned reads were also analyzed with Kraken2 software. A total of 3137 virus-positive contigs were attributed to different viruses belonging to 6 types, 17 orders, and 32 families, matching over 97 viral species. The annotated sequences can be divided into several groups: those that are homologous to genetic sequences of insect viruses (Adintoviridae, Ascoviridae, Baculoviridae, Dicistroviridae, Chuviridae, Hytrosaviridae, Iflaviridae, Iridoviridae, Nimaviridae, Nudiviridae, Phasmaviridae, Picornaviridae, Polydnaviriformidae, Xinmoviridae etc.), plant viruses (Betaflexiviridae, Bromoviridae, Kitaviridae, Potyviridae), and endogenous retroviral elements (Retroviridae, Metaviridae). Additionally, the full-length genomes and near-full length genome sequences of several viruses were assembled. We also found sequences belonging to Bracoviriform viruses and, for the first time, experimentally validated the presence of bracoviral genetic fragments in the CPB genome. Our work represents the first attempt to discover the viral genetic material in CPB samples, and we hope that further studies will help to identify new viruses to extend the arsenal of biopesticides against CPB.

Vaccinia virus had played a key role in the global smallpox eradication. However, in case of mass vaccination with various Vaccinia virus strains severe side effects were revealed sometimes ending up with lethal outcomes, especially in immunocompromised humans. Hence, in 1980 the World Health Organization recommended to cancel smallpox vaccination after declaring about smallpox eradication. Over the last 40 years, human population virtually lost immunity not only against smallpox, but also against other zoonotic orthopoxvirus infections, such as monkeypox, cowpox, buffalopox, and camelpox. All of them pose a represent increasing threat to human health and heighten a risk of emerging highly contagious viruses due to natural evolution of previous zoonotic orthopoxviruses. In order to prevent development of small outbreaks into spreading epidemics and, thus, to decrease a risk of emergence due to natural evolution of highly pathogenic for humans orthopoxviruses, efforts should be applied to develop safe new generation live vaccines based on Vaccinia virus with target virulence genes inactivation. These strains should be examined in laboratory animal models inoculated via different routes. Currently, Vaccinia virus often becomes attenuated to create live recombinant vaccines due to inserting target DNA sequences into the virus virulence genes resulting in their inactivation. Vaccinia virus strain LIVP used in the Russian Federation as smallpox vaccine as well as derivative attenuated variant LIVP-GFP created by using genetic engineering methods with inactivating its thymidine kinase gene were examined. Such viruses were intracerebrally inoculated into suckling mice at doses of 101 or 102 PFU/animal for neurovirulence assessment. Adult mice were infected intranasally, subcutaneously or intradermally at doses of 107 or 108 PFU/animal and clinical manifestations were analyzed for 14 days. On the 28th day after the onset, blood serum samples were collected from individual mice to measure virus specific antibody level by using ELISA. It was shown that recombinant Vaccinia virus strain LIVP-GFP displayed markedly lowered neurovirulence and pathogenicity for mice as compared to parental LIVP. Finally, intradermal route turned out to demonstrate the most safe and effective profile for immunization with both examined Vaccinia virus strains.

Самым простым и надежным способом защиты от вирусных инфекций является вакцинопрофилактика. При этом наибольшей протективной эффективностью обладают живые вакцины, в основе которых используют слабовирулентные для человека вирусы, близкородственные патогенным, или аттенуированные (ослабленные за счет мутаций/делеций в вирусном геноме) варианты патогенного для человека вируса. Вакцинация против оспы с использованием живого вируса осповакцины (vaccinia virus, VACV), близкородственного вирусу натуральной оспы, сыграла важнейшую роль в успехе программы глобальной ликвидации оспы, которая осуществлялась под эгидой Всемирной организации здравоохранения. Прекращение после 1980 г. противооспенной вакцинации привело к тому, что огромная часть населения Земли в настоящее время не имеет иммунитета не только к оспе, но и любым другим зоонозным ортопоксвирусным инфекциям. Это создает возможность циркуляции зоонозных ортопоксвирусов в человеческой популяции и, как следствие, приводит к изменению экологии и круга чувствительных хозяев для разных видов ортопоксвирусов. При этом использование классической живой вакцины на основе VACV для защиты от этих инфекций в настоящее время не приемлемо, так как она может обусловливать тяжелые побочные реакции. В связи с этим все более актуальной становится разработка новых безопасных вакцин против ортопоксвирусных инфекций человека и животных. Аттенуация (ослабление вирулентности) VACV достигается в результате направленной инактивации определенных генов вируса и обычно приводит к уменьшению эффективности размножения VACV in vivo. Следствием этого может быть снижение иммунного ответа при введении аттенуированного вируса пациентам в стандартных дозах. Часто используемым для встройки/инактивации в геноме VACV является ген тимидинкиназы, нарушение которого приводит к аттенуации вируса. В данной работе изучено, как введение двух точечных мутаций в ген A34R аттенуированного штамма LIVP-GFP (ТК-), увеличивающих выход внеклеточных оболочечных вирионов (EEV), влияет на свойства пато- и иммуногенности варианта VACV LIVP-GFP-A34R при интраназальном заражении лабораторных мышей. Показано, что увеличение продукции EEV рекомбинантным штаммом VACV LIVP-GFP-A34R не меняет аттенуированный фенотип, характерный для родительского штамма LIVP-GFP, но приводит к существенно большей продукции VACV-специфичных антител. Ключевые слова: вирус осповакцины; направленные мутации; аттенуация; иммуногенность.

The eradication of smallpox has become one of the greatest successes of modern health science. This great achievement was made possible thanks to the widespread vaccination of the population. The last case of human infection with smallpox virus occurred in 1977. In 1980, at the 33rd session of the World Health Assembly, routine vaccination against that infection was recommended to be discontinued due to severe post-vaccination complications. However, humanity remains vulnerable to other orthopoxvirus infections closely related to smallpox virus. Recently, the cases of human infection with ortopoxviruses such as monkeypox virus, cowpox virus, vaccinia virus have become more frequent. Also, cases of infection of people with previously unknown orthopoxvirus species are recorded. Zoonotic orthopoxviruses pathogenic for humans, circulating in nature, require a detailed study and monitoring of the emergence of new strains. Their occurrence against the background of the cessation of planned vaccination of the population against smallpox virus can lead to the emergence of new highly pathogenic viruses. This review contains information on cases of human infection with orthopoxviruses around the world for the period 2008–2018. It also describes epidemiological anamnesis and the relations between cases of human infection in different countries due to the spread of viruses over a wide area, the movement of people between countries, population contacts with domestic and wild animals. Also, this paper provides information on the infection of people with previously unknown strains of orthopoxviruses.

Vaccination is the most simple and reliable approach of protection to virus infections. The most effective agents are live vaccines, usually low-virulence organisms for humans and closely related to pathogenic viruses or attenuated as a result of mutations/deletions in the genome of pathogenic virus. Smallpox vaccination with live vaccinia virus (VACV) closely related to smallpox virus played a key role in the success of the global smallpox eradication program carried out under the World Health Organization auspices. As a result of the WHO decision as of 1980 to stop smallpox vaccination, humankind has lost immunity not only to smallpox, but also to other zoonotic, orthopoxviruscaused human infections. This new situation allows orthopoxviruses to circulate in the human population and, as a consequence, to alter several established concepts of the ecology and range of sensitive hosts for various orthopoxvirus species. Classic VACV-based live vaccine for vaccination against orthopoxvirus infections is out of the question, because it can cause severe side effects. Therefore, the development of new safe vaccines against orthopoxviral infections of humans and animals is an important problem. VACV attenuation by modern approaches carried out by targeted inactivation of certain virus genes and usually leads to a decrease in the effectiveness of VACV in vivo propagation. As a result, it can cause a diminishing of the immune response after administration of attenuated virus to patients at standard doses. The gene for thymidine kinase is frequently used for insertion/inactivation of foreign genes and it causes virus attenuation. In this research, the effect of the introduction of two point mutations into the A34R gene of attenuated strain LIVP-GFP (ТК-), which increase the yield of extracellular enveloped virions (EEV), on the pathogenicity and immunogenicity of VACV LIVP-GFP-A34R administered intranasally to laboratory mice were studied. It was shown that increase in EEV production by recombinant strain VACV LIVP-GFP-A34R does not change the attenuated phenotype characteristic of the parental strain LIVP-GFP, but causes a significantly larger production of VACV-specific antibodies.

Introduction. Currently, new directions in cancer therapy are actively developing, one of which is oncolytic immunotherapy. This approach would be to use of viruses as cancer specific cytolytic agents capable of stimulating both the tumor-specific and non-specific immune response.The objective paper was obtain a recombinant vaccinia virus containing genes encoding immunostimulating molecules and study oncolytic and immunostimulating properties of recombinant virus.Material and methods. MTT test, ELISA, methods of transient dominant selection.Results. The recombinant vaccinia virus (L-IVP_oncoB) were obtained with deletion of the gene encoding thymidine kinase and had an integrated gene encoding GM-CSF. Also the virus have deletion of the gene encoding viral growth factor and integrated genes encoding synthetic tumor-specific polyepitopic immunogens. It was shown that the modifications made to the viral genome did not affect the growth characteristics of the virus when cultured on CV-1 and 4647 cell cultures, and the cytopathogenic efficacy of the virus was determined in relation to cancer cultures of cells of various genesis. In in vivo experiment, it was revealed that the polyepitopic construct in the genome L-IVP_oncoB is able to initiate a change in the profile of cytokines.Discussion. The obtained data characterized L-IVP_oncoB as a promising cytopathogenic and immunostimulating agent and showed the need for further study of its properties as means of oncolytic immunotherapy. Conclusion. The basic experiments on the evaluation of the biological properties of the obtained L-IVP_oncoB, which are necessary for the characterization of the oncolytic virus, have been carried out.

The problems of oncological disease treatment are considered relevant and timely issues of the current research programs. Since monotherapy is increasingly clear to be less effective than combination therapy, the novel studies seek for advancement of current treatments and development of new ones employing oncolytic immunotherapy being among the most rapidly evolving approaches. Modern genetic engineering techniques enable new applications of oncolytic viruses in the frames of combined cancer therapy. These applications are feasible, due to the abilities of oncolytic viruses to destruct tumor cells, like as by changing susceptibility of cancer cells to anti-tumor drug, and upon the whole body, thus overcoming the mechanisms conferring immunoresistance of tumor cells. In the present work, we have developed a recombinant vaccinia virus which is a promising platform for designing the antitumor drugs. The following modifications of viral genome were made by means of genetic engineering: gene encoding granulocyte-macrophage colony-stimulating factor was inserted into the region of viral thymidine kinase gene; viral A34R gene encoding a membrane glycoprotein, was replaced by A34R gene with two nucleotide substitutions resulting into D110N and K151E mutations which cause increased proportion of extracellular enveloped virions during the virus reproduction. Some properties of the recombinant virus were studied in vitro. The virus was shown to produce granulocyte-macrophage colony stimulating factor, and high numbers of extracellular enveloped virions. The genome modifications had no effect upon viral replication.

Melanoma is a tumor that forms as a result of malignant transformation of melanin-producing pigment cells (melanocytes). It is the most aggressive form of skin cancer and is characterized by high resistance to chemotherapeutic drugs, which results in a need to explore alternative methods for this disease therapy. Currently, new approaches to cancer treatment are being intensely developed, oncolytic immunotherapy being one of them. This approach consists in using viruses as targeted tumor-specific cytolytic agents capable of stimulating both tumor-specific and nonspecific immune responses. A considerable body of research is currently aimed on improving the immunostimulatory properties of viruses by inserting the genes encoding immunomodulatory proteins or tumor-specific antigenic determinants into viral genomes. For melanoma, the highest number of tumor-associated antigens (TAAs) has been identified, which serve as the basis for the development of anti-tumor DNA vaccines. The immunogenicity and efficacy of these drugs, however, remain low. The bottlenecks in using DNA vaccines to treat cancer are considered to be imperfect design of polyepitope constructs, as well as inefficient delivery of therapeutic molecules directly to the target cells. A partial solution to these problems may be represented by the use of oncolytic viruses as vectors for the delivery of artificial immunogens. The recombinant vaccinia virus was obtained by transient dominant selection. The cytolytic activity of the obtained virus was tested using the MTT assay. The oncolytic activity of the virus was assessed in the mouse xenograft model obtained using malignant SK-Mel-28 cells. This paper reports the production of a recombinant L-IVP_oncoM virus, the oncolytic virus for the delivery of anticancer therapeutic genes into the cells, on the basis of the vaccinia virus strain L-IVP. Toward this end, the gene encoding the Granulocyte-macrophage colony-stimulating factor (GM-CSF) and the artificial gene encoding a polyepitope immunogen containing the epitopes of the antigens over-expressed in melanoma cells were inserted into the virus genome. These insertions were located in the proximity of the genes encoding thymidine kinase (J2R) and viral growth factor (C11L), respectively. The properties of L-IVP_oncoM were studied in in vitro experiments using cell cultures of various origin and in the in vivo experiments using the mouse xenograft model. The basic experiments to assess the biological properties of the obtained L-IVP_oncoM, which are necessary to characterize the oncolytic virus, have been carried out.

Introduction. Melanoma aggressive and fatal form of skin cancer that originates in the pigment-producing cells (melanocyte), have a high mortality rate due to the resistance of most tumors to chemotherapy. This is a reason to explore alternate therapies for this disease. One of cancer treatments that has seen intensive development recently is oncolytic immunotherapy. The essence of this approach is that use of viruses as tumor-specific cytolytic agents capable of stimulating both the tumor-specific and non-specific immune response. There is considerable research devoted to improving the immunostimulating properties of viruses by insert into the viral genome the genes encoding immunomodulatory proteins or the artificial tumor-specific polyepitopic immunogens. The highest number of tumor-associated antigens was identified for melanoma, on the basis of which anti-tumor DNA vaccines are developed. Immunogenicity and efficacy of such drugs remain low. The problem with the use of DNA vaccines for treating cancer may be the incorrect design of the polyepitopic construct, as well as the inefficient delivery of therapeutic molecules directly to the target cells. A partial solution to this problem may be use of oncolytic viruses as a vector to deliver artificial immunogens. Materials and methods. MTT test, methods of transient dominant selection, murine xenograft model using malignant cells SK-Mel-28. Results and discussion. In this study, a recombinant L-IVP_oncoM virus was obtained on the basis of the vaccinia virus strain L-IVP, which is an oncolytic virus that delivers anticancer therapeutic genes to the cells of the body. For this purpose, a gene encoding GM-CSF and an artificial gene encoding a polyepitopic immunogen consisting of epitopes of antigens over-expressed in melanoma cells were inserted into the genome of the virus. These insertions were performed in the region of the genes encoding thymidine kinase (J2R) and viral growth factor (C11L), respectively. The properties of L-IVP_oncoM were studied in a series of in vitro/in vivo experiments. Conclusion. The basic experiments on the evaluation of the biological properties of the obtained L-IVP_oncoM, which are neces- sary for the characterization of the oncolytic virus, have been carried out.

The modern approach to developing attenuated smallpox vaccines usually consists in targeted inactivation of vaccinia virus (VACV) virulence genes. In this work, we studied how an elevated production of extracellular enveloped virions (EEVs) and the route of mouse infection can influence the virulence and immunogenicity of VACV. The research subject was the LIVP strain, which is used in Russia for smallpox vaccination. Two point mutations causing an elevated production of EEVs compared with the parental LIVP strain were inserted into the sequence of the VACV A34R gene. The created mutant LIVP-A34R strain showed lower neurovirulence in an intracerebral injection test and elevated antibody production in the intradermal injection method. This VACV variant can be a promising platform for developing an attenuated, highly immunogenic vaccine against smallpox and other orthopoxvirus infections. It can also be used as a vector for designing live-attenuated recombinant polyvalent vaccines against various infectious diseases.

The mass smallpox vaccination campaign has played a crucial role in smallpox eradication. Various strains of the vaccinia virus (VACV) were used as a live smallpox vaccine in different countries, their origin being unknown in most cases. The VACV strains differ in terms of pathogenicity exhibited upon inoculation of laboratory animals and reactogenicity exhibited upon vaccination of humans. Therefore, each generated strain or clonal variant of VACV needs to be thoroughly studied in in vivo systems. The clonal variant 14 of LIVP strain (LIVP-14) was the study object in this work. A comparative analysis of the virulence and immunogenicity of LIVP-14 inoculated intranasally (i.n.), intradermally (i.d.), or subcutaneously (s.c.) to BALB/c mice at doses of 108, 107, and 106 pfu was carried out. Adult mice exhibited the highest sensitivity to the i.n. administered LIVP-14 strain, although the infection was not lethal. The i.n. inoculated LIVP-14 replicated efficiently in the lungs. Furthermore, this virus was accumulated in the brain at relatively high concentrations. Significantly lower levels of LIVP-14 were detected in the liver, kidneys, and spleen of experimental animals. No clinical manifestations of the disease were observed after i.d. or s.c. injection of LIVP-14 to mice. After s.c. inoculation, the virus was detected only at the injection site, while it could disseminate to the liver and lungs when delivered via i.d. administration. A comparative analysis of the production of virus-specific antibodies by ELISA and PRNT revealed that the highest level of antibodies was induced in i.n. inoculated mice; a lower level of antibodies was observed after i.d. administration of the virus and the lowest level after s.c. injection. Even at the lowest studied dose (106 pfu), i.n. or i.d. administered LIVP-14 completely protected mice against infection with the cowpox virus at the lethal dose. Our findings imply that, according to the ratio between such characteristics as pathogenicity/immunogenicity/protectivity, i.d. injection is the optimal method of inoculation with the VACV LIVP-14 strain to ensure the safe formation of immune defense after vaccination against orthopoxviral infections.