Preclinical Studies of Immunogenity, Protectivity, and Safety of the Combined Vector Vaccine for Prevention of the Middle East Respiratory Syndrome.

The Middle East Respiratory Syndrome (MERS) is an acute inflammatory disease of the respiratory system caused by the MERS-CoV coronavirus. The mortality rate for MERS is about 34.5%. Due to its high mortality rate, the lack of therapeutic and prophylactic agents, and the continuing threat of the spread of MERS beyond its current confines, developing a vaccine is a pressing task, because vaccination would help limit the spread of MERS and reduce its death toll. We have developed a combined vector vaccine for the prevention of MERS based on recombinant human adenovirus serotypes 26 and 5. Studies of its immunogenicity have shown that vaccination of animals (mice and primates) induces a robust humoral immune response that lasts for at least six months. Studies of the cellular immune response in mice after vaccination showed the emergence of a specific CD4+ and CD8+ T cell response. A study of the vaccine protectivity conducted in a model of transgenic mice carrying the human DPP4 receptor gene showed that our vaccination protected 100% of the animals from the lethal infection caused by the MERS-CoV virus (MERS-CoV EMC/2012, 100LD50 per mouse). Studies of the safety and tolerability of the developed vaccine in rodents, rabbits, and primates showed a good safety profile and tolerance in animals; they revealed no contraindications for clinical testing.

The Mechanism of the Stimforte Effect on the Activation of Target Cell Defense against Viral Infection.

Stimforte in a wide range of concentrations (15-225 µg/mL) totally inhibits the cytopathic activity of hepatitis C virus (HCV) in the Vero-V cell culture. Interferons (IFN) play the most important role in the suppression of infection when the drug is introduced into the culture before the infection. When Stimforte is introduced after the infection, the mechanism of action seems to be different. The activators of IFN production are mainly (or exclusively) the ligands of receptor complexes TLR-4 and NOD-2 contained in the drug. The action of these substances is probably synergistic, similar to the action of LPS and MDP in Vero-V cells.

Different effects of the immunostimulatory drug Stimforte on infections of hepatitis C virus and herpes simplex virus type 1.

Stimforte, an immune response-stimulating preparation, is active with respect to hepatitis C virus (HCV) and herpes simplex virus type I (HSV-1). The effects of Stimforte in animals infected with either HCV or HSV-1 are fundamentally different. In mice with acute herpes virus infection, Stimforte administration leads to a higher activity of natural killer cells and cytotoxic lymphocytes, and the amount of interferon (IFN) λ grows. In mice infected with HCV, Stimforte administration results in a significant increase in IFN-ß but not IFN-λ in blood and affected organs. Stimforte has been found to affect directly HCV reproduction that causes the infected cell death, but it does not affect HSV-1 reproduction in the Vero cells (V).

New Carbocyclic Amino Acid Derivatives Inhibit Infection Caused by Highly Pathogenic Influenza A Virus Strain (H5N1).

New amino acid derivatives with carbocycles of adamantine and quinaldic acid were synthesized and their in vitro antiviral activity against influenza A/H5N1 virus was evaluated. Experiments on cultured embryonic porcine kidney epithelial cells showed that amino acid derivatives suppressed viral replication. Tret-butyloxycarbonyl-DL-methionylsulfonyl-1-adamantayl ethylamine and benzyloxycarbonyl-L-trypthophanyl-1-adamantayl ethylamine compounds demonstrated high activity in all in vitro experiments. Moreover, some compounds showed virucidal activity against influenza A/H5N1 virus.

[The ability of small interfering RNA oligonucleotides to decrease the infective activity of hepatitis C virus in the cell cultures].

The use of the RNA interference technique yielded data on the antiviral activity of small interfering RNA (siRNA) oligonucleotides against hepatitis C virus (HCV) infection in the pig embryo kidney (SPEV) cell cultures. The RNA interference technique is based on the specific recognition of the mRNA target by using the specially designed siRNA (19-22 bp) oligonucleotides. In particular, it was shown that siRNA added to the monolayer of HCV-infected SPEV cells resulted in the protection of the infected cells against the cytopathogenic activity of the virus. The results were confirmed in the experiments that demonstrated the ability of RNA oligonucleotides to reduce the production of infectious (cytopathogenic) HCV by infected SPEV cells in early-stage infection.

[Effect of Zanamivir substance on infection induced by highly pathogenic avian influenza A/H5N1 in cell cultures].

In vitro experiments revealed that Zanamivir substance had high antiviral activity against infection induced by genotypes 2.2 and 2.3.2 of highly virulent influenza A/H5N1 virus in the porcine embryonic renal epithelial (PERE) cell cultures. Zanamivir at used concentrations (1.0 microg/ml or lower) had no cytotoxic properties and was equally highly effective when used for prevention (1 hour prior to cell inoculation), treatment-and-prevention (at the time of cell inoculation), and treatment (2 hours after inoculation). The high antiviral potential of Zanamivir was shown in the experiments dealing with its effect on the ability of infected PERE cells to produce an infectious virus in the first 24 hours after inoculation. The findings suggest that Zanamivir (Relenza) shows promise as an effective antiinfluenza agent.

Antiviral activity of Inonotus obliquus fungus extract towards infection caused by hepatitis C virus in cell cultures.

Fractions of Inonotus obliquus fungus water extract exhibited a virucidal effect towards hepatitis C virus: it 100-fold reduced its infective properties within 10 min. The antiviral effects of fungus extracts manifested after preventive (24 h before infection) and therapeutic use (during infection of porcine embryo kidney cells). Moreover, the data indicate that the birch fungus extracts inhibit production of infective virus by porcine embryo kidney cells.