The antiviral activity of recombinant human IFN-lambda type 1 (IFNλ-1) against culture strain of SARS-CoV-2 virus was determined by infecting a highly sensitive VeroE6 coronavirus cell culture after preincubation test (the cell monolayer was incubated with 4-fold dilutions of IFNλ-1 in a concentration range of 0.16-42,500 ng/ml in a culture medium for 12 h at 37°C) and without preincubation (simultaneous addition of different concentrations of IFNλ-1 and SARS-CoV-2 infection in a dose of 102 TCID50). The created recombinant human IFNλ-1 demonstrated obvious antiviral activity against SARS-CoV-2 virus in vitro. In the tests with and without preincubation, IFNλ-1 exhibited significant activity, although somewhat lower in variant with simultaneous addition of IFNλ-1 and virus to the cell culture. It should be noted that the antiviral effect of IFNλ-1 was observed in a wide range of concentrations.

In this study, we investigated the features of co-infection with SARS-CoV-2 and the enterovirus vaccine strain LEV8 of coxsackievirus A7 or enterovirus A71 for Vero E6 cells and Syrian hamsters. The investigation of co-infection with SARS-CoV-2 and LEV-8 or EV-A71 in the cell model showed that a competitive inhibitory effect for these viruses was especially significant against SARS-CoV-2. Pre-infection with enteroviruses in the animals caused more than a 100-fold decrease in the levels of SARS-CoV-2 virus replication in the respiratory tract and more rapid clearance of infectious SARS-CoV-2 from the lower respiratory tract. Co-infection with SARS-CoV-2 and LEV-8 or EV-A71 also reduced the severity of clinical manifestations of the SARS-CoV-2 infection in the animals. Additionally, the histological data illustrated that co-infection with strain LEV8 of coxsackievirus A7 decreased the level of pathological changes induced by SARS-CoV-2 in the lungs. Research into the chemokine/cytokine profile demonstrated that the studied enteroviruses efficiently triggered this part of the antiviral immune response, which is associated with the significant inhibition of SARS-CoV-2 infection. These results demonstrate that there is significant viral interference between the studied strain LEV-8 of coxsackievirus A7 or enterovirus A71 and SARS-CoV-2 in vitro and in vivo.

In this study, we investigated the features of co-infection with SARS-CoV-2 and nonpathogenic strain LEV8 of coxsackievirus A7 or enterovirus A71 for Vero E6 cells and Syrian hamsters. The investigation of co-infection with SARS-СoV-2 and LEV-8 or EV-A71 in the cell model was shown that a competitive inhibitory effect for these viruses were especially significant against SARS-CoV-2. Pre-infection with enteroviruses in animals caused more than a 100-fold decrease in the levels of SARS-CoV-2 virus replication in the respiratory tracts and more rapid clearance of the lower respiratory tract from infectious SARS-CoV-2. Co-infection with SARS-CoV-2 and LEV-8 or EV-A71 also reduced the severity of clinical manifestations of the SARS-CoV-2 infection for animals. Additionally, the histological data illustrated that co-infection with nonpathogenic coxsackievirus decreased the level of pathological changes by SARS-CoV-2 in the lungs. Research into the chemokine/cytokine profile demonstrated that the studied enteroviruses efficiently triggered this part of antiviral immune response, which can be associated with significant inhibition of SARS-CoV-2 infection. These results demonstrate that there exists a strong viral interference between the studied nonpathogenic strain of coxsackievirus A7 or enteroviruses A71 and SARS-CoV-2 pathogenic for humans in vitro and in vivo.

Introduction. Monitoring and research on arthropod-borne microorganisms is important. Recently, with the development of next-generation sequencing methods, many previously unknown viruses have been identified in insects. Aim of the study. Isolation of viruses from mosquitoes sampled in the Republic of Sakha (Yakutia), followed by the study of a new for Russia negevirus isolated from mosquitoes of the species Ochlerotatus caspius, including determination of its complete nucleotide sequence, phylogenetic and virological characteristics. Materials and methods. Dezidougou virus isolation was performed on C6/36 (Aedes albopictus) cell culture. Electron microscopy was performed using a JEM 1400 electron microscope. Nucleotide sequence screening was performed by NGS on a high-throughput sequencer MiSeq, Illumina (USA). Full genome nucleotide sequence was determined by Sanger sequencing. Phylogenetic analysis was performed using GenBank database, using Vector NTI Advance 11 and MEGA 11 programs. Results. The virus isolated from mosquitoes replicated efficiently in C6/36 cells, causing their death. However, it did not replicate in the mammalian cell cultures used. The isolated virus did not cause pathologic manifestations in suckling mice when infected intracerebrally. Electron microscopic examination of the purified virus-containing suspension showed the presence of spherical viral particles with a diameter of 45‒55 nm. The results of full genome sequencing identified it as belonging to Dezidougou virus, first isolated in Côte d’Ivoire. The nucleotide sequence of the genome of Yakutsk 2023 strain of Dezidougou virus was deposited in GenBank (PP975071.1). Conclusion. Dezidougou virus of genus Negevirus was isolated and characterized for the first time in the Russian Federation. Further studies on the prevalence of negeviruses, their virological features, potential importance for public health and their impact on vector competence of vectors are important and promising.

Противовирусная активность в отношении SARS-CoV-2 фармацевтической субстанции на основе иммобилизированного рекомбинантного человеческого интерферона лямбда-1

Introduction. Mosquito-borne human diseases caused by Zika virus and West Nile virus (WNV) are widespread across multiple continents and cause major outbreaks. Their ranges overlap and the possibility of mixed infections is obvious. The information of such mixed infections is limited. The aim of the study is to investigate the features of mixed infection of WNV and Zika virus in vitro and in vivo in order to assess their possible interference and/or enhancement of viral infection. Materials and methods. The study used West Nile virus and Zika virus strains Vlg27924 and MR766, respectively. The infectious activity of viruses during mono- and co-infection was determined on Vero E6 cell culture using RT-PCR, as well as on BALB/c mice using various administration schemes. Results. In vitro studies of co-infection with WNV and Zika virus showed that co-infection leads to interference, with the degree of competitive inhibition of replication being more pronounced for Zika virus, reaching 1000 times or more when compared to mono-infection. During simultaneous infection in mice, Zika virus does not affect the development of lethal infection caused by WNV. However, preliminary (4 and 20 days) infection with a sublethal dose of Zika virus reliably protects animals from subsequent administration of 10 and 100 LD50 WNV, respectively. In pre-infected and co-infected animals with Zika virus, the development of WNV-specific viral neutralizing antibodies was recorded in higher titers than in WNV monoinfected animals. Conclusion. The presence of in vitro interference between the studied orthoflaviviruses was shown, most pronounced in relation to the Zika virus. No significant effect was observed with simultaneous co-infection in vivo. However, pre-infection of mice with Zika virus provides protection to animals from lethal WNV infection due to the induction of high levels of antibodies that specifically neutralize its infectious activity.