DNA Vaccine Encoding the Artificial T-Cell Polyepitope Immunogen of Tick-Borne Encephalitis Virus.

A promising approach to the development of new means for preventing infection caused by tick-borne encephalitis virus can be DNA vaccines encoding polyepitope T-cell immunogens. A DNA vaccine pVAX-AG4-ub encoding an artificial polyepitope immunogen that includes cytotoxic and T-helper epitopes from the NS1, NS3, NS5, and E proteins of the tick-borne encephalitis virus has been obtained. The developed construct ensured the synthesis of the corresponding mRNAs in transfected eukaryotic cells. Immunization of mice with pVAX-AG4-ub induced the formation of a virus-specific T-cell response providing 50% protection from lethal infection with the virus.

Evaluation of the Anti-Viral Activity of Human Recombinant Interferon Lambda-1 against SARS-CoV-2.

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.

Design of immunogens as components of a new generation of molecular vaccines.

Three new approaches to design effective immunogens are considered. At first, we derived an expression vector from bacteriophage M13 allowing the exposure of short peptides on the virion surface. EIA demonstrates that antibodies against a recombinant phage carrying the antigenic determinant of the HIV-1 gag protein reacted with the 17-kDa core protein of the virus and also with its polyprotein precursor p55 in immunoblotting. In another approach, we chose the hepatitis B core antigen (HBcAg) particle as a vehicle for the presentation of foreign antigenic determinants to the immune system. Chimerical particles of HBcAg containing epitope of the VEE virus were obtained. A vector system for insertion of foreign antigenic determinants and production of both hybrid and wild HBcAg proteins were also obtained. The third approach relies on construction of immunogens from different T- and B-cell epitopes of the HIV-1. We suggested to construct HIV-1 vaccines in a form of the TBI (T- and B-cell epitopes containing Immunogen) with a predetermined tertiary structure, namely, a four-alpha-helix bundle. The gene of the TBI protein consisting of nine HIV-1 epitopes was synthesized and expressed in Escherichia coli cells. Mice immunized with TBI showed humoral and cellular immune responses to HIV-1. Anti-TBI antibodies displayed HIV-1 neutralizing activity. These new approaches offer promise in the development of new effective vaccines.

Glycoproteins E2 of the Venezuelan and eastern equine encephalomyelitis viruses contain multiple cross-reactive epitopes.

Enzyme immunoassay (EIA) with sixty types of monoclonal antibodies (MAbs) was used to study cross-reactive epitopes on the attenuated and virulent strains of the Eastern equine encephalomyelitis (EEE) and Venezuelan equine encephalomyelitis (VEE) viruses. All three structural proteins of the EEE and VEE viruses were demonstrated to have both cross-reactive and specific antigenic determinants. The glycoprotein E1 of EEE and VEE viruses possesses three cross-reactive epitopes for binding to MAbs. The glycoprotein E2 has a cluster of epitopes for 20 cross-reacting MAbs produced to EEE and VEE viruses. Cross-reactive epitopes were localised within five different sites of glycoprotein E2 of VEE virus and within four sites of that of the EEE virus. There are no cross-neutralising MAbs to the VEE and EEE viruses. Only one type of the protective Mabs was able to cross-protect mice against lethal infection by the virulent strains of the VEE and EEE viruses. Eight MAbs blocked the hemagglutination activity (HA) of both viruses. Antigenic alterations of neutralising and protective sites were revealed for all attenuated strains of the VEE and EEE viruses. Comparative studies of the E2 proteins amino acid sequences show that the antigenic modifications observed with the attenuated strains of the VEE virus may be caused by multiple amino acid changes in positions 7, 62, 120, 192 and 209-213. The escape-variants of the VEE virus obtained with cross-reactive MAbs 7D1, 2D4 and 7A6 have mutations of the E2 protein at positions 59, 212-213 and 232, respectively. Amino acid sequences in these regions of the VEE and EEE viruses are not homologous. These observations indicate that cross-reactive MAbs are capable of recognising discontinuous epitopes on the E2 glycoprotein.