Vol 68, No 4 (2023)

Introduction. The mouse-specific orthopoxvirus, ectromelia virus, is one of the best models that can be used to study key issues of pathogenesis, prevention, and treatment of smallpox, and to develop measures to increase virulence, transmissibility, or the ability to overcome vaccine immunity.

The aim of the work is to screen the antiviral activity of samples from Inonotus obliquus chaga and humic acid from brown coal in vitro against ectromelia virus.

Materials and methods. We used ectromelia virus, strain K-1 (reg. No V-142), obtained from the State Collection of Pathogens of Viral Infections and Rickettsioses of the State Scientific Center of Virology and Biotechnology “Vector”; Vero Е6 cell culture (No 70) from the Collection of cell cultures of the State Scientific Center of Virology and Biotechnology “Vector”. Nine samples from chaga I. obliquus and humic acid from brown coal were used to evaluate the changes in the infectivity of the ectromelia virus on cell culture using 2 schemes of application of drugs and virus (preventive and therapeutic schemes), and to assess their cytotoxicity and antiviral activity.

Results. 50% cytotoxic concentration, 50% virus-inhibiting concentrations and selectivity index were determined for all samples. The studied samples were shown to be non-toxic to the monolayer of Vero cell culture in a dilution of 300 and more micrograms/ml, while demonstrated high antiviral activity against strain K-1 of ectromelia virus in two application schemes – preventive and curative.

Conclusion. All samples tested for ectromelia virus in vitro can be considered promising for further development of drugs against diseases caused by orthopoxviruses.

Introduction. The discovery of two types of Epstein–Barr virus (EBV) (EBV-1 and EBV-2) that have different biological properties stimulated the search for neoplasms associated with each type of the virus.

The aim of the work is to study the nature of the association of nasopharyngeal cancer (NPC) with EBV-1 and EBV-2, serological activity for each viral type and the concentration of EBV DNA in the blood plasma of two gender, age and ethnic groups of NPC patients that represent geographically and climatically different regions of Russia,.

Materials and methods. In the blood plasma of patients with NPC and other non- EBV associated tumors of oral cavity (OTOC^EBV−) from the North Caucasian (NCFD) and Central (CFD) Federal Districts of Russia, the types of EBV and the concentration of viral DNA were determined using respectively «nested» and real time PCR; titers of IgG and IgA antibodies to viral capsid antigen (VCA) were measured in indirect immunofluorescence assay.

Results. The blood plasma samples testing showed that NPC and OTOC^EBV− patients were infected with both types of EBV in approximately equal proportions. In two groups of NPC patients infected with one of the virus types only, EBV-1 or EBV-2, respectively, no statistically significant differences were found between the geometric mean values of IgG and IgA anti-EBV antibody titers and viral DNA concentrations in blood plasma. The distribution of virus types was not affected by either patient gender or ethnogeographic origin. The difference was found only between age groups: EBV-2 dominated in NPC patients up to 60 years, and EBV-1 was prevalent in patients over 60 years.

Conclusion. The lack of the predominance of one of EBV types in NPC patients that are the representatives of different ethnic groups from geographically and climatically different regions, suggests that none of these factors play an important role in the NPC carcinogenesis. Evidently, each type of EBV, EBV-1 or EBV-2, if the necessary conditions arise, are able to exhibit its oncogenic potential to initiate tumor development.

Introduction. Hepatitis C is a liver disease with high chronicity, the cause of cirrhosis and hepatocarcinoma. The main obstacle to controlling hepatitis C is the lack of vaccines.

The aim of the work was to compare the immunogenic activity of nonstructural recombinant proteins NS3, NS4 and NS5B of hepatitis C virus (HCV) as components of a subunit candidate vaccine and to analyze the adjuvant properties of two available commercial drugs, polymuramil and pyrogenalum.

Materials and methods. BALB/c, DBA/2J and C57BL/6 mice were immunized with nonstructural proteins without adjuvants or with polymuramyl (NOD1 and NOD2 agonist) and pyrogenalum (TLR-4 agonist). The activity of antibodies was determined in ELISA, the cellular response – by antigen-specific lymphocyte proliferation and by production of IFN-γ in vitro.

Results. Recombinant proteins showed different immunogenicity. NS4 induced antibodies more efficiently than NS3 and NS5B. Significant differences were found in the immune response of three inbred lines mice: the level of IFN-γ in BALB/c and DBA/2J mice induced by NS5B protein was 30 times higher than in C57Bl/6 mice. In contrast, the induction of antibodies in BALB/c mice was lower than in C57Bl/6 and DBA/2J. Polymuramil did not increase the humoral response to NS5B and enhanced the cellular response only in C57BL/6 mice. The combined use of polymuramil with pyrogenalum significantly increased both the humoral and cellular response of mice to all recombinant HCV proteins.

Conclusion. Different immunogenic properties and different functions of recombinant non-structural HCV proteins indicate the feasibility of their combined inclusion in subunit vaccines. It was established for the first time that immunization with HCV proteins with a complex adjuvant (polymuramyl + pyrogenalum) has a synergistic effect, significantly exceeding the effect of each of them separately.

Introduction. African swine fever virus (ASF) is a large, enveloped virus with an icosahedral capsid morphology and a double-stranded DNA genome ranging in size from 170 to 190 kb. The replication cycle proceeds in two phases, the early phase lasting 4–6 hours and the late 8–20 hours after infection. The adaptation of the ASF virus to growth in continuous cell lines makes efficient and reliable genetic analysis and more accurate interpretation of its results.

Objective. Adaptation of a new isolate of the ASF virus to growth in a continuous cell line by the method of accelerated passages and preliminary genetic analysis of the resulting strain.

Materials and methods. For virus isolation and passaging of the ASF virus, a porcine leukocyte cell culture (PL) and continuous cell cultures of porcine origin (ST, PK, PPK-66b) were used with Eagle MEM and HLA essential media with 10% porcine or fetal serum.

Results. The article presents data on the isolation and analysis of the changes in the reproductive properties of a new African swine fever (ASF) virus isolate in the process of adaptation to growth in a continuous piglet kidney cell culture clone b (PPK-66b). The current state of the problem of cultivation of the ASF virus, the features of its reproduction, and the basis of the genetic differentiation of its isolates are described in detail. Understanding the uniqueness of the nature of the ASF virus determined the approaches to the processes of its cultivation and adaptation. In this regard, the results of studies of cultural properties, and analysis of the nucleotide sequence of 6 genes of the new isolate, as well as phylogenetic analysis of these genes with already known strains and isolates of the ASF virus are presented.

Conclusion. A new strain obtained in the process of cell adaptation of ASVF/Znaury/PPK-23 ASF virus by the accelerated passaging method reaches a high level of reproduction in 72 hours with an accumulation titer of 7.07 lg HAdE50/cm³. Primary genetic analysis allowed to establish the main phylogenetic relationships of the newly isolated strain with previously known variants of the current ASF panzootic.

Introduction. Among the available scientific literature, there are no publications addressing processes of self-regulation in the parasite-host population systems with reference to chronic infections, including the infection caused by the Epstein–Barr virus (EBV infection).

The aim of the study is to assess manifestations of the epidemic process of chronic EBV infection through the lens of the basic tenets of the theory of self-regulation of parasitic systems.

Materials and methods. The study was performed using data from scientific publications selected from such database sources as Scopus, Web of Science, Cochrane Library, PubMed, CyberLeninka, RSCI, etc. The list of analyzed publications included published articles of the authors of this study, reporting the results of the retrospective epidemiological analysis of the incidence of infectious mononucleosis in Russia in general and in Moscow in particular, as well as the results of the laboratory tests regarding the detection frequency of specific antibodies to EBV proteins.

Results. The chronic course of EBV infection promotes a close long-term interaction between the pathogen and the host. The genetic variability of the pathogen and the functions of specific and nonspecific human immune defense systems play a key role in the interaction between two heterogeneous populations and underlie their phasal self-transformation. A variety of social and natural factors (adverse chemical, physical, biological, climatic impacts, etc.) trigger the reactivation of chronic EBV infection, thus providing the continuous existence of additional sources of infection in the host population.

Conclusion. The analysis of the manifestations of chronic EBV infection in the context of the theory of self-regulation of parasitic systems promotes the understanding of the factors underlying the unevenness of its epidemic process. The obtained data can be adjusted for other infections having similar transmission mechanisms and virus life cycles (including other herpes infections) to map out strategies to control the epidemic process of chronic infections spread by aerosol transmission of the pathogen.