Coding nucleotide sequences of tick-borne encephalitis virus strains isolated from human blood without clinical symptoms of infection

Беликов, С. И.; Леонова, Г Н; Кондратов, И. Г.; Романова, Е. В.; Павленко, Е. В.

doi:10.1134/s1022795410030087

Cited by 8 publications

(8 citation statements)

References 32 publications

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“…Evidence that viral genetic factors may also contribute to the severity of infection was supported by the genetic characterization of different TBEV strains from symptomatic and asymptomatic infections. Mutations affecting the virion proteins, NS3, NS5 proteins, and even the 3= NCR were linked to altered pathogenic properties (93,94). Despite the progress in investigating viral pathogenesis, the background of the TBFV pathomechanism remains poorly understood, especially for less-common TBFVs.…”

Section: Pathogenesismentioning

confidence: 99%

Tick-Borne Flaviviruses, with a Focus on Powassan Virus

2018

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SUMMARYThe tick-borne pathogen Powassan virus is a rare cause of encephalitis in North America and the Russian Far East. The number of documented cases described since the discovery of Powassan virus in 1958 may be <150, although detection of cases has increased over the past decade. In the United States, the incidence of Powassan virus infections expanded from the estimated 1 case per year prior to 2005 to 10 cases per year during the subsequent decade. The increased detection rate may be associated with several factors, including enhanced surveillance, the availability of improved laboratory diagnostic methods, the expansion of the vector population, and, perhaps, altered human activities that lead to more exposure. Nonetheless, it remains unclear whether Powassan virus is indeed an emerging threat or if enzootic cycles in nature remain more-or-less stable with periodic fluctuations of host and vector population sizes. Despite the low disease incidence, the approximately 10% to 15% case fatality rate of neuroinvasive Powassan virus infection and the temporary or prolonged sequelae in >50% of survivors make Powassan virus a medical concern requiring the attention of public health authorities and clinicians. The medical importance of Powassan virus justifies more research on developing specific and effective treatments and prevention and control measures.

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Section: Pathogenesismentioning

confidence: 99%

Tick-Borne Flaviviruses, with a Focus on Powassan Virus

2018

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“…Additionally, comparisons of strains isolated from patients infected with TBEV identified several differences in NS5 across strains with varying disease outcomes. Interestingly, two studies identified mutations at position 692, where Ile correlated with high pathogenicity strains while Val was associated with low pathogenicity [ 65 , 66 ]. A third study compared strains isolated from patients with severe TBE found Ile or Thr at position 692; Thr has only been found in European human pathogenic strain Ljublijana I [ 67 ].…”

Section: Effects Of Viral Proteins On Virulencementioning

confidence: 99%

“…The authors speculate this substitution may improve interaction with host replication trans-acting factors. Mutations S634T/Y, R677K, and A724S were also associated with varying degrees of pathogenicity (substitutions associated with high pathogenicity strains are noted first, followed by the residue position and the low pathogenicity substitution), although their role in virulence has not been tested experimentally [ 65 , 66 ]. It should be noted that these mutations also reside within the IFN-I antagonism functional region.…”

Section: Effects Of Viral Proteins On Virulencementioning

confidence: 99%

“…Mutations associated with differing pathogenicity have been identified in both the coding and noncoding regions of the flavivirus genome through genetic analysis of natural isolates [ 49 , 65 , 66 , 67 , 69 ] and mutations derived during infectious cDNA recovery [ 31 , 51 , 64 ]. Most of these have not been studied via reverse genetics, and thus their contribution to flavivirus virulence remains unexplored.…”

Section: Effects Of Viral Proteins On Virulencementioning

confidence: 99%

“…Substitutions found in naturally attenuated isolates are likely more informative, as they represent mutations that have developed and been maintained within the natural TBEV population, whereas it is unclear whether mutations arising during laboratory manipulation would withstand selective pressure in the natural TBFV life cycle. Two such mutations, a deletion at position 111 in the capsid protein and Ser45Phe in the NS3 protein, have been consistently correlated with reduced pathogenicity in natural TBEV isolates [ 65 , 69 , 70 ]. Both mutations affect proper cleavage of the polyprotein, as the deletion in C occurs in a cleavage signal domain and the mutation at position 45 of NS3 may interfere with efficient catalytic activity [ 71 ].…”

Section: Effects Of Viral Proteins On Virulencementioning

confidence: 99%

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Viral Determinants of Virulence in Tick-Borne Flaviviruses

Kellman¹,

Offerdahl²,

Melik

et al. 2018

Viruses

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Tick-borne flaviviruses have a global distribution and cause significant human disease, including encephalitis and hemorrhagic fever, and often result in neurologic sequelae. There are two distinct properties that determine the neuropathogenesis of a virus. The ability to invade the central nervous system (CNS) is referred to as the neuroinvasiveness of the agent, while the ability to infect and damage cells within the CNS is referred to as its neurovirulence. Examination of laboratory variants, cDNA clones, natural isolates with varying pathogenicity, and virally encoded immune evasion strategies have contributed extensively to our understanding of these properties. Here we will review the major viral determinants of virulence that contribute to pathogenesis and influence both neuroinvasiveness and neurovirulence properties of tick-borne flaviviruses, focusing particularly on the envelope protein (E), nonstructural protein 5 (NS5), and the 3′ untranslated region (UTR).

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Louping ill virus (LIV) in the Far East

Леонова¹,

Кондратов

Maystrovskaya³

et al. 2014

Arch Virol

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This study focused on finding, culturing, and identifying the biological and genetic characteristics of three louping ill virus (LIV) strains in the south of the Russian Far East. The Primorye-155-77 and Primorye-20-79 virus strains were isolated from Ixodes persulcatus ticks, and the Primorye-185-91 strain was isolated from the blood of a person after a tick bite. According to the hemagglutination and neutralization tests, Primorye-155-77, Primorye-20-79 and Primorye-185-91 had weak reactivity with antibodies in an antiserum against tick-borne encephalitis virus. In Primorye-155-77 and Primorye-20-79, the sequences of the 5' ends of the 2456-nucleotide-long viral RNA including the 5' untranslated region (UTR) and genes of the capsid protein, prM protein and envelope E protein were determined. The complete genome sequence of Primorye-185-91 was determined. The E protein gene of the Negishi strain differed from those of three analyzed strains, as there were mutations resulting in the replacement of three amino acids: Ala163Thr, Asp193Asn and Ala313Thr. The homology of Primorye-185-91 to LIV 369/T2 was 97.57 %, and to the Penrith strain, it was 98.36 %. Phylogenetic analysis showed that Primorye-155-77, Primorye-20-79 and Primorye-185-91 are related to LI/A and LI/K strains isolated in England and Scotland and to the Negishi strain; these strains have a common progenitor. Negishi-like strains were represented by one subtype of louping ill virus, i.e. the British subtype (LIV-Brit). The possibility is discussed of a single introduction of the virus to the Far Eastern region (Japan and Primorsky Krai) from a single natural locus more than 50 years ago.

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Coding nucleotide sequences of tick-borne encephalitis virus strains isolated from human blood without clinical symptoms of infection

Cited by 8 publications

References 32 publications

Tick-Borne Flaviviruses, with a Focus on Powassan Virus

Tick-Borne Flaviviruses, with a Focus on Powassan Virus

Viral Determinants of Virulence in Tick-Borne Flaviviruses

Louping ill virus (LIV) in the Far East

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