Experimental infection of H5N1 HPAI in BALB/c mice.

BACKGROUND: In 2005 huge epizooty of H5N1 HPAI occurred in Russia. It had been clear that territory of Russia becoming endemic for H5N1 HPAI. In 2006 several outbreaks have occurred. To develop new vaccines and antiviral therapies, animal models had to be investigated. We choose highly pathogenic strain for these studies. RESULTS: A/duck/Tuva/01/06 belongs to Quinghai-like group viruses. Molecular markers-cleavage site, K627 in PB2 characterize this virus as highly pathogenic. This data was confirmed by direct pathogenic tests: IVPI = 3.0, MLD50 = 1,4Log10EID50. Also molecular analysis showed sensitivity of the virus to adamantanes and neuraminidase inhibitors. Serological analysis showed wide cross-reactivity of this virus with sera produced to H5N1 HPAI viruses isolated earlier in South-East Asia. Mean time to death of infected animals was 8,19+/-0,18 days. First time acute delayed hemorrhagic syndrome was observed in mice lethal model. Hypercytokinemia was determined by elevated sera levels of IFN-gamma, IL-6, IL-10. CONCLUSION: Assuming all obtained data we can conclude that basic model parameters were characterized and virus A/duck/Tuva/01/06 can be used to evaluate anti-influenza vaccines and therapeutics.

Investigation of mumps vaccine failures in Minsk, Belarus, 2001-2003.

The purpose of this study was to investigate mumps vaccine failures (VF) in a highly vaccinated population of Minsk, Belarus, and to investigate a possible role for virus strain-specific immunity. During our 3-year study period, 22 adults were admitted to the Infectious Diseases Hospital in Minsk with a diagnosis of mumps. A genotype H1 mumps virus (MuV) strain was identified in all patients. Of 15 patients from whom the paired sera were collected, 9 were confirmed to have been previously vaccinated. Serological examinations indicated primary VF in seven of these cases and secondary VF in two. Despite almost all vaccinated patients possessing MuV specific IgG, few possessed neutralizing antibody to the vaccine strain and titers were nominal. Importantly, none of the sera were able to neutralize a genotype H MuV strain. Our results demonstrate the importance of assaying for neutralizing antibody and support the assertion that antigenic differences between wild type and vaccine MuV strains may play a role in cases of breakthrough infection in vaccinees.

Designing and engineering of DNA-vaccine construction encoding multiple CTL-epitopes of major HIV-1 antigens.

A synthetic T cell immunogen (TCI) has been designed as a candidate DNA-based vaccine against Human immunodeficiency virus (HIV)-1 using cytotoxic T lymphocytes (CD8(+) CTL) and T-helper lymphocytes (CD4(+) Th) epitopes retrieved from the Los Alamos HIV Molecular Immunology Database. The protein 392 amino acids in length contains about eighty CTL-epitopes, many of which are overlapping and are totally restricted by ten different HLA class I molecules. To be able to detect CTL responses induced by a DNA vaccine in experimental animals, additional epitopes, restricted by mouse and Macaque rhesus major histocompatibility complex (MHC) class I molecules, were included in the target immunogen. The gene encoding the TCI protein was assembled, cloned into vector plasmids and expressed in a prokaryotic and a eukaryotic system. The presence of HIV-1 protein fragments in the immunogen structure was ascertained by ELISA and immunoblotting using panels of HIV-1-positive sera and monoclonal antibodies to p24. It has been demonstrated that DNA vaccine can induce both specific T cell responses (CTL and blast transformation) and specific antibodies in mice immunized with pcDNA-TCI.

Comparative analysis using a mouse model of the immunogenicity of artificial VLP and attenuated Salmonella strain carrying a DNA-vaccine encoding HIV-1 polyepitope CTL-immunogen.

Two systems have been examined for delivery of DNA-vaccine encoding a HIV-1 polyepitope CTL-immunogen (TCI). One is intended for i.m. injection and is in the form of an artificial virus like particle containing eukaryotic expression plasmid pcDNA-TCI encapsulated within a spermidine-polyglucin conjugate. The other is intended for mucosal immunization and is based on attenuated Salmonella typhimurium strain 7207, which can deliver pcDNA-TCI directly into professional antigen-presenting cells (APC). After immunization, the artificial VLP and recombinant Salmonella induced an enhanced HIV specific serum antibody, proliferative and CTL responses compared to those induced by naked pcDNA-TCI. The most significant responses were produced when pcDNA-TCI was delivered by Salmonella.

Construction of artificial virus-like particles exposing HIV epitopes, and the study of their immunogenic properties.

One of the major problems in the development of successful recombinant vaccines against human immunodeficiency virus (HIV) is that of correct identification of a safe and effective vaccine delivery system with which to induce protective immunity using soluble protein antigens. An original method for constructing artificial immunogens in the form of spherical particles with yeast dsRNA in the center and hybrid proteins exposing epitopes of an infectious agent on the surface is reported. The dsRNA and the proteins were linked with spermidine-polyglucin-glutathione conjugates. Particles exposing HIV-1 epitopes were constructed, and their immunogenicity tested.