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

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

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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 Sleeveless 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 Lilac 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.