Cell cultures are used as classic models for virology. Development of transgenesis and genome editing methods leads to a new possibility in creation of transgenic cell lines that can serve as more suitable models for virological research. This work describes the obtaining transgenic cell lines and the study of their susceptibility to viral infections.

Crimean-Congo hemorrhagic fever (CCHF) is a widespread arbovirus disease with a mortality rate of up to 40 % in humans. Despite the severity of the disease and the geographic distribution of CCHF, no vaccine or therapeutic agents are currently registered. The paper presents data on a recombinant rhabdovirus expressing a modified glycoprotein GPC of the CCHF virus, an isolate epidemiologically relevant for the Russian Federation.

This work is devoted to obtaining a homogeneous recombinant receptor-binding domain of the Spike glycoprotein of two variants of the SARS-CoV-2 virus (Delta B.1.617.2, Omicron B.1.1.529) for the study of antigen — antibody complexes with immunoglobulins of COVID-19 reconvalescents.

Coronaviridae is a family of single-stranded RNA (ssRNA) viruses that can cause diseases with high mortality rates. SARS-CoV-1 and MERS-CoV appeared in 2002‒2003 and 2012, respectively. A novel coronavirus, SARS-CoV-2, emerged in 2019 in Wuhan (China) and has caused more than 5 million deaths in worldwide. The entry of SARS-CoV-1 into the cell is due to the interaction of the viral spike (S) protein and the cell protein, angiotensin-converting enzyme 2 (ACE2). After infection, virus assembly occurs in Golgi apparatus-derived vesicles during exocytosis. One of the possible participants in this process is LAMP1 protein. We established transgenic Vero cell lines with increased expression of human LAMP1 gene and evaluated SARS-CoV-1 and SARS-CoV-2 production. An increase in the production of both viruses in LAMP1-expressing cells when compared with Vero cells was observed, especially in the presence of trypsin during infection. From these results it can be assumed that LAMP1 promotes SARS-CoV-1 and SARS-CoV-2 production due to enhanced exocytosis.

Bluetongue, or catarrhal fever of sheep, is a viral vector-borne infection of ruminants, which is one of the economically significant arbovirus infections of animals. It is transmitted by blood-sucking insects of the Culicoides genus. Viral protein VP7 is a group-specific core protein of the virus, conservative for all known serotypes, and therefore represents the most suitable target for creation of diagnostic tests. To develop an immunochemical method for detecting viral infection, a panel of high-affinity monoclonal antibodies to VP7 has been obtained. The N -terminal fragment of VP7 expressed in E. coli and inactivated viral particles were used as immunogens. The resulting monoclonal antibodies are useful for detecting the virus in infected cells. As a species-specific antigen, a recombinant TrxA‑VP7_a protein has been created that contains spatial epitopes similar to those of the native viral antigen. With its help, promising antibodies were selected for diagnostics of the disease by competitive enzyme-linked immunosorbent assay, which allows the detection of specific antibodies to bluetongue virus in the sera of infected animals. Using competitive solid-phase ELISA, it has been shown that antibodies that interact most effectively with the TrxA-VP7_a protein (Bt14, Bt15, Bt18, Bt26, Bt33, Bt34, and Bt35) recognize close or overlapping VP7 epitopes. The interaction with the antigen of almost all the antibodies obtained was inhibited by reference specific sera against the bluetongue virus of 24 serotypes. The monoclonal antibody Bt14 showed maximum ability to block the interaction of VP7 with specific sera against 24 bluetongue virus serotypes. Thus, the resulting panel of monoclonal antibodies to VP7 of the bluetongue virus can be used to detect viral infection, as well as a component of kits for serological diagnosis of the disease.

This article is devoted to the development and evaluation of the immunoblotting test system for serological diagnosis of African swine fever (ASF), based on the highly purified recombinant p30 of ASF virus (ASFV) strain Stavropol 01/08 (Stavropol 2008), representative of the ASFV currently circulating in the Russian Federation. The main project stages are as follows: (i) cloning of the central hydrophilic region of the ASFV gene CP204L (p30) into a prokaryotic vector; (ii) expression and chromatographic purification of the recombinant product p30 with thioredoxin and poly-histidine site (p30e1_TrxA_6xHis); (iii) development of the immunoblotting test system (Rec p30-IB) using the highly purified recombinant p30; and (iv) evaluation of Rec p30-IB using sera and organ samples from domestic pigs and wild boars experimentally or naturally infected by ASFV. Testing of the Rec p30-IB showed the diagnostic specificity and sensitivity of the assay to be 98.75% and 100.00%, respectively. High sensitivity of the Rec p30-IB allowed the detection of ASFV-specific antibodies in samples of organs of the immune system and blood sera, collected from domestic pigs and wild boars, starting from 6 to 8 days post-infection, regardless of virus virulence, seroimmunotype and geographic origin of the samples (East Europe, South Europe, West Europe, Central and south-east Africa).

Control of African swine fever (ASF) is complicated by the lack of specific prevention medications.The attempts to obtain live attenuated vaccines by conventional methods were not promising, and the inactivated or subunit vaccines have not been developed so far (N.J. Petiska,

In recent decades, a threat of spreading Rift Valley fever (RVF) to Asia and Europe raises serious concerns.Within many years, vaccines against RVF were developed in several ways including designing attenuated vaccine versions, inactivated or genetically engineered vaccines.A serious hazard of the RVF agent requires developing sufficiently immunogenic preparations providing both RVF specific prevention and safety precautions in production procedures.Therefore, this work was aimed at molecular and biological characterization of an attenuated RVF virus (RVFV) strain 1974-VNIIVViM including search for high-tech cell culture systems for the virus growth and determination of its antigenic and/or immunogenic relationship with a virulent strain Entebbe.The results of the investigations showed that the virus accumulated in continuous cell cultures like saiga kidney (SK), Siberian mountain goat kidney (PSGK-60) and MDVK (calve kidney cell culture) at high titers with infectious (8.53±0.21lg MICLD 50 /cm 3 ) and antigenic (1:64 to 1:128 in the passive hemagglutination test, PHT) activity levels.We determined optimal regime of the virus growth in BHK-21/13 (Syrian hamster kidney cell culture) using a roller culture method: the culture bottle rotation speed of 12 to 15 r.p.h.; the infection dosage of 0.01 to 0.001 MLD 50 /cell; the first 12 hours of the culture at pH = 6.4 to 6.8.Further, pH is maintained at 7.2 to 7.6 for 48 to 72 hours of culture at 37 С, which provides the raw virus production at high infectivity (8.5 to 8.9±0.2 lg MICLD 50 /cm 3 ) and antigenicity (1:128 to 1:256 in PHT and 1:625 to 1:3125 in solid phase ELISA) levels.Phylogenetic analysis of the nucleotide sequences of 3 sites in S and/or M segments showed that it was closely related to strains Smithburn and Entebbe allowing their grouping into a separate cluster.Comparative analysis of nucleotide sequences of genes encoding glycoproteins Gn and Gc, and the nucleoprotein N, shows that most of the substitutions in the sequences of the genes of the RVFV strain 1974-VNIIVViM are synonymous and do not alter the primary amino acid sequence, with insertion and deletion missing.In the nucleotide sequence encoding glycoprotein Gn of strain 1974-VNIIVViM we found 8 substitutions relative to a similar sequence of M segment of a virulent strain Entebbe, and 14 substitutions when compared with M segment of strain Smithburn.A lower (as compared with other attenuated strains) amount of significant amino acid substitutions in RVFV antigenic components was revealed; thus, strain 1974-VNIIVViM selection as a source of immunodominant proteins and/or raw virus for vaccine production seems to be well-grounded.