ASSESSMENT OF CYTOTOXICITY AND ANTIVIRAL ACTIVITY AGAINST SARS-COV-2 OF THE MIXTURE OF LACTOFERRIN, ARTEMISININ, AND AZITHROMYCIN IN VITRO

Lactoferrin, artemisinin, and azithromycin exhibit a broad spectrum of antiviral, immunomodulatory, and anti-inflammatory effects. The experiments show that these drugs partially inhibit the infection caused by SARS-CoV-2 in vitro. This allows us to conclude that the effects on the entry of virions into cells mediated by each of these substances taken separately are insufficient for complete inhibition of the SARS-CoV-2 infection. The study was aimed to perform in vitro assessment of cytotoxicity and antiviral activity against the laboratory SARS-CoV-2 strain of the mixture of active ingredients: lactoferrin, artemisinin, and azithromycin. We used the Vero CCL81 (ATСС) cell line and the Dubrovka laboratory strain of SARS-CoV-2 (GenBank ID: MW161041.1), isolated in the Vero CCL81 cell culture from the nasopharyngeal swab of patient with СOVID-19. Cytotoxic effects and antiviral activity against SARS-CoV-2 of the drug mixture were assessed based on the cytopathic effects using the MTT (methylthiazolyldiphenyl-tetrazolium bromide) assay. Hydroxychloroquine was used as a reference drug. It has been shown that at high (MOI 100) and low (MOI 20) multiplicity of infection used in the Vero CCL 81 cell culture, the mixture of artemisinin, lactoferrin and azithromycin has a significant effect on the SARS-CoV-2 reproduction, and IC50 (half maximal inhibitory concentration) is estimated as the 1: 2 dilution in both cases. The findings make it possible to conclude that the studied mixture is low toxic and shows significant antiviral effects in vitro. © 2022 Group of Companies Med Expert, LLC. All rights reserved.

[Comparative study of Wuhan-like and omicron-like variants of SARS-CoV-2 in experimental animal models].

INTRODUCTION: The variability of SARS-CoV-2 appeared to be higher than expected, the emergence of new variants raises concerns. The aim of the work was to compare the pathogenicity of the Wuhan and BA.1.1/Omicron variants in BALB/c mice and Syrian hamsters. MATERIALS AND METHODS: The study used strains of SARS-CoV-2: Dubrovka phylogenetically close to Wuhan-Hu-1, and LIA phylogenetically close to Omicron, BALB/c mice, transgenic mice B6.Cg-Tg(K18-ACE2)2Prlmn/HEMI Hemizygous for Tg(K18-ACE2)2Prlmn, Syrian golden hamsters. Animals were infected intranasally, pathogenicity was estimated by a complex of clinical, pathomorphological and virological methods. RESULTS: Comparative studies of SARS-CoV-2 Dubrovka and LIA strains on animal models demonstrated their heterogeneous pathogenicity. In parallel infection of BALB/c mice with Dubrovka and LIA variants, the infection proceeded without serious clinical signs and lung damage. Infection with the LIA strain resulted to a systemic disease with a high concentration of viral RNA in the lungs and brain tissues of animals. The presence of viral RNA in mice infected with the Dubrovka strain was transient and undetectable in the lungs by day 7 post-infection. Unlike the mouse model, in hamsters, the Dubrovka strain had a greater pathogenicity than the LIA strain. In hamsters infected with the Dubrovka strain lung lesions were more significant, and the virus spread through organs, in particular in brain tissue, was observed. In hamsters infected with the LIA strain virus was not detected in brain tissue. CONCLUSION: The study of various variants of SARS-CoV-2 in species initially unsusceptible to SARS-CoV-2 infection is important for monitoring zoonotic reservoirs that increase the risk of spread of new variants in humans.

[Generation of SARS-CoV-2 Mouse Model by Transient Expression of the Human ACE2 Gene Mediated by Intranasal Administration of AAV-hACE2]

One of the most important steps in the development of drugs and vaccines against a new coronavirus infection is their testing on a relevant animal model. The laboratory mouse, with well-studied immunology, is the preferred mammalian model in experimental medicine. However, mice are not susceptible to infection with SARS-CoV-2 due to the lack of human angiotensin-converting enzyme (hACE2), which is the cell receptor of SARS-CoV-2 and necessary for the entry of the virus into the cell. In present work, it was shown that intranasal administration of the adeno-associated vectors AAV9 and AAV-DJ encoding the hACE2 provided a high level of expression of ACE2 gene in the lungs of mice. In contrast, the introduction of the AAV6 vector led to a low level ACE2 expression. Infection with SARS-CoV-2 of mice expressing hACE2 in the lungs led to virus replication and development of bronchopneumonia on the 7th day after infection. Thus, a simple method for delivering the human ACE2 gene to mouse lungs by intranasal administration of the AAV vector has been proposed. This approach enabled rapid generation of mouse model for studying coronavirus infection.