Post-exposure administration of chimeric antibody protects mice against European, Siberian, and Far-Eastern subtypes of tick-borne encephalitis virus.

Tick-borne encephalitis virus (TBEV) is the most important tick-transmitted pathogen. It belongs to the Flaviviridae family and causes severe human neuroinfections. In this study, protective efficacy of the chimeric antibody chFVN145 was examined in mice infected with strains belonging to the Far-Eastern, European, and Siberian subtypes of TBEV, and the antibody showed clear therapeutic efficacy when it was administered once one, two, or three days after infection. The efficacy was independent of the TBEV strain used to infect the mice; however, the survival rate of the mice was dependent on the dose of TBEV and of the antibody. No enhancement of TBEV infection was observed when the mice were treated with non-protective doses of chFVN145. Using a panel of recombinant fragments of the TBEV glycoprotein E, the neutralizing epitope for chFVN145 was localized in domain III of the TBEV glycoprotein E, in a region between amino acid residues 301 and 359. In addition, three potential sites responsible for binding with chFVN145 were determined using peptide phage display libraries, and 3D modeling demonstrated that the sites do not contact the fusion loop and, hence, their binding with chFVN145 does not result in increased attachment of TBEV to target cells.

Complete Genome Sequencing of Borrelia valaisiana and Borrelia afzelii Isolated from Ixodes persulcatus Ticks in Western Siberia.

Lyme disease, caused by bacteria of the Borrelia burgdorferi sensu lato complex, is the most frequent tick-borne infection in Eurasia. Here, we report the complete genome sequence of the Borrelia valaisiana Tom 4006 and Borrelia afzelii Tom 3107 strains isolated from Ixodes persulcatus ticks in western Siberia.

A protective chimeric antibody to tick-borne encephalitis virus.

The efficiency of several mouse monoclonal antibodies (mAbs) specific to the tick-borne encephalitis virus (TBEV) glycoprotein E in post-exposure prophylaxis was assessed, and mAb14D5 was shown to be the most active of all those studied. It was proven that the hybridoma cell line 14D5 produced one immunoglobulin H chain and two L chains. They were used to construct chimeric antibodies ch14D5a and ch14D5b, the affinity constants of which were 2.6 × 10(10)M(-1) and 1.0 × 10(7)M(-1), respectively, according to the SPR-based ProteOn biosensor assay. The neutralization index (IC50) of ch14D5a was 0.04 µg/ml in the focus reduction neutralization test. In in vivo experiments, ch14D5a at a dose of 10 µg/mouse resulted in a 100% survival of the mice infected with 240 LD50 of TBEV. This chimeric antibody is promising for further development of prevention and therapeutic drugs against TBEV.

Whole-genome sequencing of Borrelia garinii BgVir, isolated from Taiga ticks (Ixodes persulcatus).

Most Lyme borreliosis cases in Russia result from Borrelia garinii NT29 group infection. Borrelias of this group circulate exclusively in Ixodes persulcatus ticks, which are seldom found beyond Russia and the far east. Here we report the whole-genome sequence of Borrelia garinii BgVir isolated from an I. persulcatus female.