Vol 56, No 1 (2011)

The review characterizes the currently used cold-adapted donor strains of influenza virus attenuation to prepare cold-adapted reassortants with actual epidemic influenza virus strains. It considers new procedures for preparing attenuated influenza virus strains for live influenza vaccines, as well as analytical methods and the genome composition of reassortants. Recent data on the safety of live cold-adapted influenza vaccines (LCAIVs), including those on the genetic stability of vaccine reassortants and the immunogenicity and efficacy of these vaccines for different age groups, are discussed. There is evidence for the design of live human vaccines against avian influenza. It is concluded that LCAIVs are highly effective for immunization of children.

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 μg/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.

The paper describes a simple, rapid screening of samples potentially containing Crimean-Congo hemorrhagic fever (CCHF) virus strains, by applying the restriction analysis of amplicones, for the differentiation of CCHF virus genotypes that are characteristic of Europe from virus biovariants uncharacteristic of this area, this technique requiring no sequence at the first stage. For this screening, the authors propose to use the PCR fragment of CCHF L segment that comprises a variable region, as well as AluI and HaeIII restriction endonucleases. The screening scheme proposed for samples potentially containing CCHF virus may aid investigators to monitor in order to detect uncharacteristic genotypic virus variants in the Russian Federation and other European countries.

Ebola virus virulence in guinea pigs, which appears through virus adaptation to this animal host, correlates with substitutions in the gene encoding vp24 protein. In particular, the substitution His → Tyr186 was found when obtaining strain 8 ms. An attempt was made to clarify the functional role of this substitution in a transgenic fruit fly model. Using the drosophila transformation technique provided transgenic strains that contained genomic insertions of wild-type Ebola virus vp24 gene and the mutant gene with the His → Tyr substitution at the above position. Thus, the drosophila strains carrying the sequences encoding for the vp24 proteins of Ebola virus Zaire and 8 ms in pUAST vector were obtained. This makes it possible to study the expression of transgenic constructs in various D. melanogaster organs and tissues.

The paper describes the specific features of the 2009-2010 epidemic season in Russia and the world, which are due to the wide spread of a new pandemic strain of influenza A(H1N1)v virus. There is an unusual early upsurge in the incidence of influenza and acute respiratory viral infection (ARVI) (in October-November 2009) with its peak at weeks 45 to 48 of the year with a succeeding reduction to the seasonal values by its end. The circulation of influenza B virus strains was recorded in February-April 2010, which was responsible for the higher epidemic thresholds of morbidity in a number of Russia's regions. A study of the antigenic properties of the strains defined their relationship to the reference strains A/California/07/2009 (H1N1)v and B/Brisbene/60/2008. There were strains with amino acid substitutions at position 222 of hemagglutinin in the population of pandemic influenza A(H1N1)v virus. The strains of the new pandemic influenza A(H1N1)v virus were resistant to remantadine and susceptible to oseltamivir, zanamivir, and arbidol. The influenza B virus strains were susceptible to oseltamivir, zanamivir, and arbidol. The proportion of pathogens of some ARVIs was as follows: parainfluenza viruses, 9.8%; adenoviruses, 5.5%; respiratory syncytial virus, 4.8%; and Mycoplasma pneumonia, 0.6%. There is evidence that there is a need for further monitoring of influenza viruses in Russia.