Structural Modeling of the NS 3 helicase of Tick-borne encephalitis virus and their virtual screening of potent drugs using molecular docking

Inhibition of tick-borne encephalitis virus in cell cultures by ribavirin

Tick-borne encephalitis virus (TBEV) belonging to arboviruses is a major member of zoonotic pathogens. TBEV infection causes severe human encephalitis without specific antiviral drugs. Due to its use of antiviral drug against a wide range of viruses, we investigated antiviral effect of ribavirin against TBEV in susceptible human cell lines A549 and SH-SY5Y. Ribavirin displayed minor cytotoxicity on multiple cell lines. Ribavirin obviously impaired TBEV replication and protected the infected cells from cytopathic effect. Importantly, ribavirin markedly inhibited TBEV propagation, as evidenced by impairment of TBEV production and viral RNA replication. Treatment with ribavirin (co-treatment and post-treatment) led to a dose-dependent reduction in TBEV titers as well as the viral RNA levels. Antiviral protein myxovirus resistance A mRNA expression was significantly up-regulated and signal transducer and activator of transcription 3 was activated in TBEV-infected A549 cells upon the ribavirin treatment. Induction of inflammatory cytokine tumor necrosis factor alpha by TBEV was decreased in A549 cells with the treatment of ribavirin, whereas interleukin 1 beta release appeared to be unaffected. These results suggest that ribavirin might represent a promising safe and effective antiviral drug against TBEV.

An RNA-dependent RNA polymerase inhibitor for tick-borne encephalitis virus

Tick-borne encephalitis virus (TBEV) is a medically important representative of the Flaviviridae family. The TBEV genome encodes a single polyprotein, which is co/post-translationally cleaved into three structural and seven non-structural proteins. Of the non-structural proteins, NS5, contains an RNA-dependent RNA polymerase (RdRp) domain that is highly conserved and is responsible for the genome replication. Screening for potential antivirals was done using a hybrid receptor and ligand-based pharmacophore search likely targeting the RdRp domain. For the identification of pharmacophores, a mixture of small probe molecules and nucleotide triphosphates were used. The ligand/receptor interaction screenings of structures from the ZINC database resulted in five compounds. Zinc 3677 and 7151 exhibited lower cytotoxicity and were tested for their antiviral effect against TBEV in vitro. Zinc 3677 inhibited TBEV at micromolar concentrations. The results indicate that Zinc 3677 represents a good target for structure-activity optimizations leading potentially to a discovery of effective TBEV antivirals.