Vol 55, No 5 (2010)

Provision of investigations with collection pathogen cultures must ensure the adequacy of the properties of museum cultures to the characteristics of their natural prototypes. The standard preparation of collection cultures by the protocols that is optimal to preserve the original properties of a natural pathogen population, all other things being equal, assures the compatibility of the results of studies irrespective of the place and time of their performance, i. e. their continuity. The original biological properties of microorganisms can be preserved under laboratory conditions when the minimum number of enrichment and restorative culture passages is made using the biological objects that have a minimum impact on the geno- and phenotype of specific culture strains. To unifying approaches to identifying stored and incoming pathogens, to standardize the principles of identification, passport issuing, long-term preservation of the original biological properties of the reference cultures of strains, and to set up a system for the interdepartmental information support of collection tasks are problem areas for the creation of a common federal collection of microorganisms.

In our earlier studies, we have shown that amino acid changes in the hemagglutinin (HA) of influenza H5N1 virus escape mutants conferring resistance to monoclonal antibodies (MAbs) may correlate with a decrease of virus virulence for mice and that the virulence can be restored to the initial level by serial passages. In the present study, the mutations identical to those observed in the HA of a low-virulent escape mutant and its readapted variant were introduced into the HA gene by site-specific mutagenesis. The viruses produced by plasmid transfection and containing the HA gene either of A/Vietnam/1203/2004 (H5N1) virus with a deletion at the cleavage site, or of a low-virulent escape mutants, or of its readapted variant, in the presence of 6 genome segments of A/Puerto Rico/8/34 (H1N1) virus and the NA gene of A/Vietnam/1203/2004 (H5N1) virus, were assayed for virulence. Determination of virulence for mice indicated that amino acid substitution in the HA gene of a low-virulent escape mutant produced a decrease of virulence whereas the additional mutation identical to that acquired by the escape mutant in the course of readaptation restored the virulence to initial level. The findings are the first strong evidence for lower H5N1 virus virulence resulting from the amino acid substitution changing the antigenic specificity of HA and for restored virulence arising from compensating mutation in the HA gene.

The paper presents the data of an investigation of the genetic polymorphism of the pol gene encoding viral integrase (IN) in a HIV subtype A infected population in the Lipetsk Region. The investigators analyzed 32 virus subtype A samples obtained in 2002-2007. Polymorphism at the codons associated with IN resistance to chemicals was observed in 7 virus variants. The found substitutions had a pattern of genetic polymorphism and were unassociated with resistance in 6 patients with the test subtype A population. At the same time, minor RAL resistance mutation was revealed in 1 (3.1%) virus variant while the similar mutations in the subtype G population were about 10%.

The investigation was undertaken to study the molecular characteristics of Epstein-Barr virus (EBV) LMP1 gene samples amplified from the tumor and intact tissues of patients with EBV-negative forms of gastric carcinoma (GC). The genetic structure of these samples determined by their sequencing was compared with that of the gene samples isolated from the cells of oropharyngeal washing specimens from the same patients with GC, as well as peripheral blood lymphocytes of patients with infectious mononucleosis (IM) and blood donors. The findings suggest that the samples of tumor tissue LMP1 from patients with GC have higher divergence than those from patients with IM and blood donors although no specific variants of the gene for GC were found. Comparison of LMP1 sequences from tumor tissue and cells of oropharyngeal washing specimens from the same patients with EBV-negative GC revealed the common LMP1 variant in 2 cases while they differed in 3 cases. The findings are an initial step in studying the role of EBV in the carcinogenesis of EBV-negative GC that is likely to be established by investigations on representative clinical material, by applying the up-to-date technologies.

Deformed wing virus (DWV) was first detected in the honey bee Apis mellifera by reverse transcriptase-polymerase chain reaction (RT-PCT) in the Moscow Region. Molecular phylogenetic analysis of the detected nucleotide sequence of the virus fragment VP2-VP1 of DWV demonstrated that the Russian virus sequence is united in the common cluster with all earlier revealed nucleotide sequences of DWV in the Genbank worldwide, which confirms the previous conclusions that this virus has recently distributed in the honey bee by Varroa destructor mite. It has been shown that the level of homology for all DWV nucleotide sequences is 98%, except for nucleoside sequence of 7D isolate from Turkey (96% homology), 96% homology with Kakugo virus and 84-86% homology with Varroa destructor virus 1; there is a preponderance of insignificant nucleotide substitutions, mainly transitions, which supports the evolutionary propinquity of 3 viruses.

The paper considers horizontal transmission routes of baculovirus infection in the gypsy moth (Lymantria dispar L.). The original method for modeling natural processes in controllable conditions allowed one to estimate the influence of factors on the occurrence of epizooties. The authors investigated 3 possible models of virus transmission from infected to uninfected gypsy moths: 1) infected and test caterpillars were kept and fed together (a complex route); 2) those which were in the immediate vicinity, but deprived of eating together (an aerial route); 3) test caterpillars were fed on the leaves on which infected caterpillars had eaten (an oral route). The investigations have shown that the complex and oral routes out of the considered models may be considered to be effective infection transmission routes for the horizontal spread of epizooties. Furthermore, the availability of sufficient amount of infected caterpillars in the population leads to a reduction in the resistance of healthy insects to other diseases. Thus, by taking into account the capacity of larvae for passive migration, the purpose of insecticidal treatment is to set up a few infection foci that will be a source for the spread of epizootias and contribute to an overall viability reduction of a pest population.