Репозиторий Университета

© 2018 Chernokhaeva, Rogova, Kozlovskaya, Romanova, Osolodkin, Vorovitch and Karganova. Tick-borne encephalitis (TBE), caused by the TBE virus (TBEV), is a serious public health threat in northern Eurasia. Three subtypes of TBEV are distinguished. Inactivated vaccines are available for TBE prophylaxis, and their efficacy to prevent the disease has been demonstrated by years of implication. Nevertheless, rare TBE cases among the vaccinated have been registered. The present study aimed to evaluate the protective efficacy of 4 TBEV vaccines against naturally circulating TBEV variants. For the first time, the protection was evaluated against an extended number of phylogenetically distinct TBEV strains isolated in different years in different territories. The protective effect did not strongly depend on the infectious dose of the challenge virus or the scheme of vaccination. All vaccines induced neutralizing antibodies in protective titers against the TBEV strains used, although the vaccines varied in the spectra of induced antibodies and protective efficacy. The protective efficacy of the vaccines depended on the individual properties of the vaccine strain and the challenge virus, rather than on the subtypes. The neutralization efficiency appeared to be dependent not only on the presence of antibodies to particular epitopes and the amino acid composition of the virion surface but also on the intrinsic properties of the challenge virus E protein structure.

© 2018 The Authors. We studied minor variants within two tick-borne encephalitis virus (TBEV) populations with a common ancestor: the mouse brain-adapted variant EK-328c and the tick-adapted variant M. High-throughput sequencing with custom amplicons from RTPCR viral RNA was performed on Illumina MiSeq 2*250 paired-end v2 chemistry. Using the LowFreq program (default settings) and Sanger-sequenced consensus as a reference, variants with an abundance of 1% and above within the studied populations were identified. Using the obtained data in the context of our previous studies, we concluded that TBEV variants, which are different from the major population phenotype and can become a major part of the viral population under favourable environmental conditions, can exist at abundances of less than 1% in the long-term. The comparison of our data with the literature allowed us to conclude that the laboratory variant EK-328c and variant M have similar SNV counts to TBEV variants from natural populations and some fast-evolving RNA viruses.