[The avidicity index of specific IgG in the diagnosis of diseases caused by west Nile and tickborne encephalitis viruses].

The significant antigenic crossovers between West Nile virus (WNV) and tick-borne encephalitis virus (TBEV) make the immunological diagnosis of these diseases difficult. The avidicity index of virus-specific class G immunoglobulins (IgG) was used as a criterion for the differentiation of an immune response to WNV or TBEV in patients and convalescents. The panels of the sera sampled from patients with tick-borne encephalitis and convalescents in the Novosibirsk and Tomsk Regions and in the Primorye Territory and from those with West Nile fever and convalescents in the Volgograd Region. The determination of the avidicity index could establish that in the convalescents' sera, the avidicity index of virus-specific IgG was much higher than that in the patients' sera in the acute phase of infection. In relation to heteroantigen, the avidicity index and the positivity coefficient were substantially less than those in the reaction with homoantigen. The findings have indicated that the determination of the value of the avidicity index of virus-specific IgG and the positivity coefficient makes it possible to differentiate West Nile fever and tick-borne encephalitis with confidence on the basis of solid-phase enzyme immunoassay in determining virus-specific IgG in the sera of patients and convalescents in different regions of Russia.

[Cloning the gene for vaccinia virus strain L-IVP growth factor in Escherichia coli]. / Klonirovanie v kletkakh Escherichia coli gena faktora rosta virusa ospovaktsiny shtamma L-IVP.

The growth factor gene of the vaccinia virus LIVP strain has been primarily cloned in a 4.3 kbp long BamHI-EcoRI fragment and then subcloned in a 440 bp fragment. It was shown that clone 4 of the LIVP strain contains a single copy of this gene while the WR strain contains a repeat. The gene is located on a 4.3 kbp BamHI-EcoRI fragment but not on a 2.2 kbp fragment and has four nucleotide changes, three of which result in amino acid substitutions.

[Cloned variants of the L-IVP strain of the vaccinia virus]. / Izuchenie klonovykh variantov shtamma L-IVP virusa ospovaktsiny.

Genomes of vaccinia strain L-IVP and its cloned variants were investigated by restriction and Southern blotting analysis. The strain L-IVP was shown to be heterogeneous and to consist of variants which differed in the genome structure and properties. Clone 1 derived from L-IVP was less reactogenic than the original strain for rabbits inoculated intradermally and had mutations in the right terminus of the genome. All the clones were stable in passages in the chorioallantoic membranes of developing chick embryos and roller BHK-21 cell cultures.