Isolation and characterization of tick-borne encephalitis virus from Ixodes persulcatus in Mongolia in 2012by Memi Muto, Boldbaatar Bazartseren, Bazartseren Tsevel, Erdenechimeg Dashzevge, Kentaro Yoshii, Hiroaki Kariwa

Ticks and Tick-borne Diseases

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Year
2015
DOI
10.1016/j.ttbdis.2015.05.006
Subject
Insect Science / Microbiology / Parasitology / Infectious Diseases

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Text

Accepted Manuscript

Title: Isolation and characterization of tick-borne encephalitis virus from Ixodes persulcatus in Mongolia in 2012

Author: Memi Muto Boldbaatar Bazartseren Bazartseren

Tsevel Erdenechimeg Dashzevge Kentaro Yoshii Hiroaki

Kariwa

PII: S1877-959X(15)00088-6

DOI: http://dx.doi.org/doi:10.1016/j.ttbdis.2015.05.006

Reference: TTBDIS 488

To appear in:

Received date: 8-1-2015

Revised date: 16-3-2015

Accepted date: 9-5-2015

Please cite this article as: Muto, M., Bazartseren, B., Tsevel, B., Dashzevge, E.,

Yoshii, K., Kariwa, H.,Isolation and characterization of tick-borne encephalitis virus from Ixodes persulcatus in Mongolia in 2012., Ticks and Tick-borne Diseases (2015), http://dx.doi.org/10.1016/j.ttbdis.2015.05.006

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Isolation and characterization of tick-borne encephalitis virus from Ixodes persulcatus in 1

Mongolia in 2012. 2 3

Memi Muto 1)* , Boldbaatar Bazartseren 2)* , Bazartseren Tsevel 2) , Erdenechimeg Dashzevge 2) , 4

KentaroYoshii 1)# , Hiroaki Kariwa 1) 5 6 1)

Laboratory of Public Health, Graduate School of Veterinary Medicine, Hokkaido University, 7

Sapporo, Hokkaido 060-0818, Japan 8 2)

Laboratory of Virology, Institute of Veterinary Medicine, Zaisan, Ulaanbaatar 17024, Mongolia 9 *Both authors contributed equally to this work 10 11 #Corresponding author: Kentaro Yoshii, PhD., DVM 12

Postal address: Laboratory of Public Health, Graduate School of Veterinary Medicine, Hokkaido 13

University, kita-18 nishi-9, kita-ku, Sapporo, Hokkaido 060-0818, Japan 4

Tel/fax: +81-11-706-5213 15

E-mail: kyoshii@vetmed.hokudai.ac.jp 16 17

Word count for Abstract: 165 18

Word count for text: 2746 19

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Abbreviation 20 21

BHK baby hamster kidney 22

CPE cytopathic effect 23 p.i. post infection 24

E envelope 25

IFA immunofluorescence assay 26

LGTV Langat virus 27

MOI multiplicity of infection 28

ORF open reading frame 29

PCR polymerase chain reaction 30

PFU plaque forming unit 31

RNA ribonucleic acid 32

RT-PCR reverse transcription polymerase chain reaction 33

TBE tick-borne encephalitis 34

TBEV tick-borne encephalitis virus 35

UTR untranslated region 36 37

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Abstract 38 39

Tick-borne encephalitis virus (TBEV) is a zoonotic virus belonging to the genus Flavivirus, in the 40 family Flaviviridae. The virus, which is endemic in Europe and northern parts of Asia, causes severe 41 encephalitis. Tick-borne encephalitis (TBE) has been reported in Mongolia since the 1980s, but 42 details about the biological characteristics of the endemic virus are lacking. In this study, 680 ticks 43 (Ixodes persulcatus) were collected in Selenge aimag, northern Mongolia, in 2012. Nine Mongolian 44

TBEV strains were isolated from tick homogenates. A sequence analysis of the envelope protein 45 gene revealed that all isolates belonged to the Siberian subtype of TBEV. Two strains showed similar 46 growth properties in cultured cells, but their virulence in mice differed. Whole genome sequencing 47 revealed only thirteen amino acid differences between these Mongolian TBEV strains. Our results 48 suggest that these naturally occurring amino acid mutations affected the pathogenicity of Mongolian 49

TBEV. Our results may be an important platform for monitoring TBEV to evaluate the 50 epidemiological risk in TBE endemic areas of Mongolia. 51 52

Keywords: Flavivirus, Tick-borne encephalitis, Mongolia 53 4

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Introduction 55 56

Tick-borne encephalitis virus (TBEV), a member of the genus Flavivirus within the 57

Flavivirdae family, causes severe encephalitis in humans. Tick-borne encephalitis (TBE) is a 58 zoonotic disease and is endemic in Europe, Russia, and northern parts of Asia, including Japan 59 (Lindquist and Vapalahti, 2008; Suss, 2008; Takashima et al., 1997). TBEV is maintained between 60 ticks (family Ixodes) and wild vertebrate hosts in nature. Humans are not involved in the natural 61 transmission of TBEV and are only accidental hosts. Although, vaccines are currently available, TBE 62 has a significant impact on public health in these endemic regions (Kunz and Heinz, 2003). 63

TBEV has been divided into three subtypes: the European subtype, the Siberian subtype and 64 the Far-Eastern subtype (Ecker et al., 1999). These subtypes cause different symptoms and mortality 65 (Gritsun et al., 2003). The European subtype, which is distributed throughout Europe, causes a 66 biphasic fever and milder form of encephalitis, and the mortality rate is up to 2% (Dumpis et al., 67 1999; Suss, 2008). The distribution range of the Far-Eastern subtype covers Eastern Russia, northern 68

China, and Japan. Infection with this subtype of TBEV provokes the most severe neural disorder, 69 including encephalitis and meningoencephalitis, and the mortality rate is up to 30% (Ecker et al., 70 1999). The Siberian subtype is widely distributed throughout Russia and the case mortality rate is 1 6–8%. Despite the milder form of encephalitis caused by Siberian subtype compared to the 72