Biological properties of domestic strain vRub-Ant of rubella virus

Introduction. Rubella is a mild infectious disease affecting mainly children and is caused by the rubella virus, part of the Matonoviridae family, genus Rubivirus. Rubella causes congenital rubella syndrome (CRS) and is the main cause of developmental abnormalities, especially blindness and deafness. There is no specific treatment for rubella and CRS. In order to avoid possible complications from rubella infection, a live attenuated rubella vaccine based on the foreign strain of Wistar RA 27/3 rubella virus is used. However, the actual, more effective and preferred vaccine strain the rubella virus for the Russian Federation is considered to be a viral strain of rubella circulating on its territory. The aim of the study was to study the biological properties of the developed domestic cold-adapted strain vRub-Ant circulating in the territory of the Russian Federation. Materials and methods. Following cell cultures were used in the study human embryo lung diploid cell strain LECH-3, transferable cell line from embryonic kidney cells of green monkeys Vero CCL-81 and Vero ECC, human mesenchymal stem cells, human peripheral blood mononuclear cells (PBMC). Cell cultures were grown on a DMEM/F12 nutrient medium with the addition of 5% fetal bovine serum. Swabs from the pharynx and nasal passages from a child with rubella were used as clinical virus-containing material. Monoclonal anti-idiotypic antibodies m(anti-ID)Ab were used to assess the expression level of alpha/beta and gamma interferon receptors (/ and IFN-R)Ab, imitating the biological effects of alpha/beta and gamma interferons (/ and IFN) of humans. The cultural, virological, immunochemical and serological research methods were applied in the study. Results. Attenuation of the vRub-Ant clinical isolate of rubella virus was carried out for 20 consecutive passages on LECH-3 diploid cells at a reduced temperature of 30C. The main biological markers of attenuation were determined to be ts and ca phenotypes. The avirulence of the attenuated viral strain (att-phenotype) was assessed by the level of expression of / and IFN-R. A lower level of / and IFN-R expression was found on the membranes of human PBMC induced by the vaccine strain vRub-Ant in comparison with the parent wild variant of the rubella virus. This trait,the att phenotype, is characteristic of attenuated viral strains. It has been shown that the vaccine strain vRub-Ant has lost neurotropism and was unable to bind to the membrane receptors of the brain (MRB) of guinea pig embryos, unlike its parent rubella virus strain. The high immunogenicity of the domestic cold-adapted strain vRub-Ant was confirmed by high titers of neutralizing rubella antibodies observed in guinea pigs immunized subcutaneously with one vaccination dose of the virus. Conclusion. A domestic attenuated vaccine strain vRub-Ant of the rubella virus that has the main biological markers of attenuation (ts-ca and att phenotypes) has been developed. The vaccine strain vRub-Ant induces a high levels of neutralizing antibodies in guinea pigs following the immunization with a single vaccination dose of the vaccine. The viral strain vRub-Ant has lost its tropism to the MRB of guinea pig embryos, unlike its parent variant

Virus-inhibitory activity of the antigen complex of opportunistic pathogenic bacteria against SARS-CoV-2

Introduction. The antigen complex of opportunistic pathogenic bacteria (ACOPB) has a protective effect against avian influenza viruses, herpes virus type 2, and other viruses that cause acute respiratory viral infections. In the context of the COVID-19 pandemic, an important task is to find out whether ACOPB has a protective effect against SARS-CoV-2. The purpose of the study was to evaluate in vitro the ACOPB virus-inhibitory activity against the Dubrovka laboratory strain of SARS-CoV-2. Materials and methods. The study was performed using Vero cell line CCL-81, human peripheral blood mononuclear cells (PBMCs), mouse monoclonal anti-idiotypic antibodies structurally mimicking biological effects of human interferons (IFNs), the Dubrovka laboratory strain of SARS-CoV-2. The infectivity of the virus was assessed by two methods: by virus titration using cell cultures and the limiting dilution method when the results are assessed by a cytopathic effect; the second method was a plaque assay. The in vitro virus inhibition test was performed using the cell culture susceptible to SARS-CoV-2; the mixture containing a specific dose of the virus and a two-fold dilution of ACOPB was transferred to the cell culture after the ACOPB medication had interacted with the virus at 4C for 2 hours. The ACOPB virus-inhibitory activity against SARS-CoV-2 was assessed by the functional activity of / and IFN receptors (RIFN) in human PBMCs induced in vitro by ACOPB and the ACOPB mixture with the specific dose of SARS-CoV-2. The RIFN expression level was measured by the indirect membrane immunofluorescence test. Results. Hemagglutination assay using chicken, mouse, guinea pig, and human red blood cells was performed for detection of the SARS-CoV-2 inhibitory protein. The lysate of Vero CCL-81 cells infected with SARS-CoV-2 Dubrovka demonstrated the highest hemagglutination activity with guinea pig red blood cells and low titers of hemagglutination in the virus-containing fluid. The virus inhibition test in the Vero CCL-81 cell culture demonstrated that ACOPB inhibited 10 doses of SARS-CoV-2 Dubrovka with the titer 1 : 32, providing 100% protection of the cell culture for 8 days (the monitoring period). ACOPB induced / and RIFN expression on membranes of human PBMCs in in vitro cultures and decreased RIFN / and expression after its interaction with SARS-CoV-2 Dubrovka. Conclusion. The experimental studies including the virus inhibition test in the cell culture susceptible to SARS-CoV-2 Dubrovka and the indirect membrane immunofluorescence assay using monoclonal anti-idiotypic antibodies mimicking IFN-like properties demonstrated that ACOPB had both an immunomodulatory and a virus-inhibitory effect

Characterization of binding of Varicella zoster virus vaccine strains to preparations of mouse brain membrane receptors

Purpose: characterization of vFiraVax (the causative agent of chickenpox - VZV) and vZelVax (the causative agent of shingles - HZ) vaccine strains by their ability to bind to preparations of brain membrane receptors of SPF BALB/c mice.Materials and Methods. The study was performed on cold-adapted vFiraVax VZV and vZelVax HZ vaccine strains developed by the authors on the basis of the wild-type parental pFira VZV virus (chickenpox causative agent) and the latent parental lpZel HZ virus (shingles causative agent); vOka vaccine strains isolated from vaccines against VZV infection from two manufactures (United Kingdom and USA); the HEL-3 strain of diploid cells from human embryonic lung tissue, the MC 27 strain of diploid cells from human embryonic musculocutaneous tissue, primary and diploid cells from guinea pig fetal fibroblasts. The VZV infectivity was estimated by the limiting dilution method using MC 27 cell cultures or guinea pig fetal fibroblasts. The virus titer was measured by the hemadsorption test performed with suspensions of red blood cells from guinea pig or human type 0 positive blood. Negative staining and electron microscopy were used to study the virus preparation. The immunogenicity of vFiraVax VZV and vZelVax HZ virus strains was compared with the immunogenicity of vOka VZV virus strains from different manufacturers by using a cross-neutralization test with immune sera.Results. The Russian cold-adapted vFiraVax VZV and vZelVax HZ vaccine strains, the latent parental lpZel HZ virus and the vOka VZV vaccine strain (United Kingdom) did not bind to preparations of brain neuroreceptors of SPF BALB/c mice as distinct from the wild-type parental pFira VZV variant and vOka VZV vaccine strains (USA); the absent neurotropism of Russian vFiraVax VZV and vZelVax HZ vaccine strains is not connected with the decreased immunogenicity in relation to foreign counterparts; the electron microscope study of the vFiraVax VZV virus containing liquid concentrate detected VZV nucleocapsids.Conclusion. The differences in the VZV ability to bind to preparations of brain membrane receptors of SPF BALB/c mice can be explained by the differences in the technology of vaccine manufacturing, including attenuation techniques, obtaining of the vaccine strain, specific characteristics of the latent parental lpZel HZ virus. The absence of the binding with brain neuroreceptors of SPF mice has been proved for the Russian vFiraVax VZV and vZelVax HZ vaccine strains which was is not connected with a decrease in their immunogenicity. The method of assessment of the binding ability of VZV vaccine strains can be used as a preliminary characteristic of neurotropism for newly created vaccine strains and for vaccine products