Download West Nile Virus

State Research Center of Virology and Biotechnology “VECTOR”
Institute of Molecular Biology
Department of Molecular Virology
INTERNATIONAL COLLABORATION
IN STUDY OF THE FLAVIVIRUSES
V.B. Loktev
Lescar et al, Cell, 2001
Family:
Flaviviridae
Genus:
Prototype virus
Flavivirus
Yellow fever virus
Flavivirus genus contains
approximately 72 viruses
Pestivirus
Bovine diarrhea virus
Hepacivirus
Hepatitis C virus
Groups of the flavivirus
• yellow fever virus group
• tick-borne encephalitis virus
 mosquito-borne, 1 species
 tick-borne, 16 species
•
•
 no known vector, 6 species
 mosquito-borne, 10 species
•
•
•
•
•
•
group
Rio Bravo virus group
Japanese encephalitis virus
group
Tyuleniy virus group
Ntaya virus group
Uganda S virus group
Dengue virus group
Modoc virus group
Tentative Species in the
Genus
– tick-borne viruses
– mosquito-borne viruses
– viruses with no known
vector





tick-borne, 3 species
mosquito-borne, 5 species
mosquito-borne, 4 species
mosquito-borne, 4 species
no known vector, 5 species
 2 species
 11 species
 5 species
ICTV-2002
Flavivirus Genome
•
•
•
•
•
ss (+) RNA genome
Approximately 11 kb
5’-m7GpppAmp cap
Lacks 3’-polyA tail
Codes for
– 3 structural proteins
• Capsid (C), membrane
(prM/M), envelope (E)
– 7 non-structural proteins
• NS1, NS2A, NS2B, NS3,
NS4A, NS4B, NS5
Lescar et al, Cell, 2001
Envelope proteins of intracellular
and extracellular flavivirus virions.
E-protein
• Approximately 54 kDa
• Dimer positioned parallel to
virus surface
• Three domains
 I - Central domain
 II - Dimerization domain
 III - Immunogenic/Receptor
binding domain
Volk et al, 2004
Volk et al, 2004
Non-structural proteins
NS1
46 kDa
Main antigen,
modified of cell
membrane
Possibly
participation in
RNA replication
14 and 22
NS2a
and NS2b kDa
Function
unknown
Replicase?
NS2b – co-factor
for protease
NS3
Several enzyme
activities
Protease,
helicase
NS4a and 16 and 27
kDa
NS4b
Membraneassociated
proteins
Modification of cell
membranes
NS5
Polymerase
RNA polimerase
and
methyltransherase
activity
70 kDa
103 kDa
Major Flavivirus Diseases
• Dengue
• Japanese encephalitis
• Tick-borne encephalitis
• West Nile
• Yellow fever
Current Flavivirus Vaccines
Live attenuated/weakened
• Yellow fever
• Japanese encephalitis
Inactivated/killed
• Japanese encephalitis
• Tick-borne encephalitis
No vaccines
• Dengue
• West Nile
Sohn YM, Emerg Infect Dis. 2000 Jan-Feb;6(1):17-24.
West Nile Virus
• First isolated in 1937 in Uganda.
• First recorded epidemic in Israel
in 1950’s.
• Found in Africa, Europe and Asia.
• Introduced into Western
hemisphere during 1999 in New
York.
Family: Flaviviridae
Genus: Flavivirus
Japanese encephalitis virus group
• Alfuy virus
• Japanese encephalitis virus
• Kokobera virus
• Koutango virus
• Kunjin virus
• Murray Valley encephalitis virus
• St. Louis encephalitis virus
• Stratford virus
• Usutu virus
• West Nile virus
ICTV-2002
West Nile Virus Transmission Cycle
Mosquito vector
Incidental infections
Incidental infections
Bird
reservoir
hosts
Animal hosts:
• Bird
• Horse
• Human
• Hamster
• Mouse
ВЗН обнаружен в более чем в 115
различных видах организмов !!!
Pathogenesis
• Virus infects host via
•
•
•
mosquito bite.
Multiplication in tissues and
lymph nodes near site of
entry.
Virus moves to blood via
lymphatics; viremia
detected early in infection.
Infection of central nervous
system takes place.
Solomon et al, BMJ, 2003
Outbreak of WNV infection
Solomon et al, BMJ, 2003
States with West Nile virus and those with
increased risk of acquiring the virus,
November 1999
States at risk from West Nile virus
States with West Nile virus
Gubler et al. 2002
States with West Nile virus and those with
increased risk of acquiring the virus,
November 2000
States at risk from West Nile virus
States with West Nile virus
Gubler et al. 2002
States with West Nile virus and those with
increased risk of acquiring the virus,
November 2001
States at risk from West Nile virus
States with West Nile virus
Gubler et al. 2002
States with West Nile virus, September
2002
States with West Nile virus
Gubler et al. 2002
West Nile virus in 2002
Solomon et al, BMJ, 2003
West Nile in the United
States
States of Cases of Deaths
USA
WN
infection
Mortality
rate %
1999
1
62
7
11,3
2000
3
21
2
9,5
2001
10
66
9
13,6
2002
42
4156
286
6,9
2003
45
9006
220
2,44
USA – 2004, on 31 August
– 1053 human cases (28 fatal)
• California – 326, Arizona –
316, Colorodo – 141
– 85 positive donors
– 3978 positive birds (dead) in
44 states
– 4024 positive mosquito pools
in 31 states
• Canada
– 15 human cases
– 325 positive birds
www.promedmail.org
Campbell et all, Lancet, 2002
Phylogenetic tree of West Nile viruses
Lanciotti, et al // Virology.2002. V. 298, P. 96-105.
New moments in epidemiology of
the WN infection
• Blood transfusion (737 donors on
25.11.2003)
• Organs transplantation
• Breast-feeding
• Stem cells transplantation
• Laboratory incidents
• Transplacental pathway
Number of publications on WNV
infection (Medline data)
400
350
Publication
300
250
200
150
100
50
0
1995
1996
1997
1998
1999
2000
2001
2002
2003
Incidence of reported cases of dengue hemorrhagic fever,
worldwide, 1968 to 1998, and showing a dramatic increase in
incidence in the recent past.
Distribution of dengue hemorrhagic fever in the Americas before 1981 and during the
period from 1981 to 1998, showing spread of the disease as a result of reinvasion of the
region by the Aedes aegypti vector and the introduction and transmission of multiple
dengue serotypes.
West Nile in the Russia, outbreak of WN
infection in 1999
380 confirmed cases
including 38 fatalities
Volgograd
Astrakhan
95 confirmed cases
including 5 fatalities
2000
1999
1998
1997
1996
1995
1993
1992
1991
100
90
80
70
60
50
40
30
20
10
0
1967
Cases
West Nile in Astrakhan Region
Butenko et al 2000
West Nile virus in the Russia in 2002
West Nile virus in 2003
2300 km
4000 km
Phylogenetic tree of Siberian variants of WN viruses
2002,
Western Siberia
Human case in Novosibirsk
• Latent time – 14 days?
• Clinical picture – 10 days fever
• Vaccination – Complete course of immunization
against TBE virus
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•
•
Titer against TBE virus (IgG) – 1:400 (constant)
Titer against WNV (IgG) – up to 1:3200
RT PCR – positive
Sequence of cDNA fragment (gene E protein) –
genotype I of WNV, Volgograd like.
• Additional – PCR positive on Lyme disease, mixed
infection?!
(Morozova et a, 2004, personal report)
Conclusion on WN infection in the
Russia
• Outbreak of the WN infection in Russia were
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•
•
recorded in 1999. The Volgograd isolates had the
greatest homology (99.6%) with WN-Romania1996 mosquito strain RO97-50;
WNV was found in birds which were collected in
the south of Western Siberia in the summerautumn of 2002-2003;
Siberian variants of WNV showed the maximum
level of homology with the strain WNV/LEIVVlg99-27889 isolated in Volgograd in 1999.
The high level of homology between these
sequences suggests a connection between WNV
circulating in Northern Caspian region and
Western Siberia.
7
6
5
4
3
2
2003
2002
2001
2000
1999
1998
1997
1996
1995
1990
1985
1980
1975
1970
1965
1960
1955
1950
1945
0
1940
1
Number of cases (per/100.000) of TBE infection in
the Russia (USSR) during 1940-2001.
TBE infection in Austria and Czech
Rep.
New Variants of Tick-Borne Encephalitis
Virus Discovered by Retrospective
Investigation of Fatal Cases of Tick-Borne
Encephalitis with Hemorrhagic Syndrome
Occurred in Novosibirsk Region (Russia)
During Summer of 1999
Background:
In 1999, 447 TBE cases confirmed by enzyme immunoassay
were reported in Novosibirsk region. The mortality rate was
2.0%.
The fatal outcomes of eight patients were associated with
development of a pronounced hemorrhagic syndrome.
Archival samples of formalin-fixed brain tissue from the fatal
cases were collected only in March 2000. Previously they were
stored for 89 months in 10% formaldehyde solution at room
temperature
Distribution of hemorrhagic TBE cases in
Novosibirsk region in summer of 1999.
Main clinical dates for
hemorrhagic TBE
Age of patients:
Latent period
44 - 69 years
12,8 days
First fever symptoms
0 day
First hemorrhagic symptom
7 day
CNS manifestation
Massive hemorrhagic
manifestation
Dead
10 day
13-14 day
16 day
Homology (%) between the nucleotide acid sequences of
prototype strains for various subtypes of TBEV and OHF virus
Subtypes
neud
sofjin
botsad
koltsovo1
koltsovo19
koltsovo23
koltsovo29
omskhf
1
European
neud
100.00
81.94
84.72
81.67
80.28
78.61
80.83
80.28
2
Far
Eastern
3
Siberian
sofjin
81.94
100.00
85.28
99.72
92.50
91.39
92.78
77.78
botsad
84.72
85.28
100.00
85.00
83.33
82.50
83.61
78.89
omskhf
80.28
77.78
78.89
78.06
76.67
75.00
77.50
100.00
Phylogenetic tree for
nucleotide sequences
of protein E of TBEV
Subtype 3
(Siberian subtype)
Subtype 1
(European subtype)
Subtype 2
(Far Eastern
subtype
Far Eastern Subtype of TBEV
1937
Sofiin
1953
1993
Oshima
1979
1977
1987, Crimea
1939
1999, Koltsovo
1937 Sofiin 1993
Oshima
1953
1979
Conclusion on hemorrhagic TBEV:
Analysis of nucleotide sequences of these fragments showed
that homology with subtype 3 (Siberian subtype) of TBEV
was approximately 82%.
The new variants cluster together with subtype 2 (Far Eastern
subtype) of TBEV (homology, 94.7%) in phylogenetic
analysis.
Thirteen new amino acid mutations in domain II of protein E
were mapped.
We conclude that new and unusual variants of TBEV have
recently emerged in Novosibirsk region. These variants
appear to be capable of inducing a hemorrhagic syndrome in
the infected humans.
Summary:
• Emerging of new variants of
flaviviruses is new threat for the
human and public health.
• Modern variants of flaviviruses are
distributed in most countries of
world.
• The flaviviruses is hot problem of
modern virology.
• SRC VB «Vector»
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–
V.A. Ternovoi
A.M. Shestopalov
E.V. Protopopova
S.I. Zolotykh
Yu.V.Kononova
S.V. Netesov
V.B. Loktev
• Novosibirsk State Medical
Academy
– G.P. Kurzhukov
• 1st Municipal Clinical Infectious
Hospital of Novosibirsk
– G.Y. Ivanov
– Y.V. Sokolov
• D.I. Ivanovsky Institute of
Virology, Russian Academy of
Medical Sciences, Moscow
– M.Yu. Shchelkanov
– V.A. Aristova
– V.L. Gromashevsky,
– D.K. L’vov
• University of North Carolina, USA
– R.W. Ryder
• Stanford University, USA
–
A.V. Loktev
• Institute of Systematic and
Ecology of Animal, SB RAS,
Novosibirsk
– A.V. Druzyaka
• Institute of Epidemiology and
Microbiology, SB RAMS, Irkutsk
– M.A. Khasnatinov
• National Center for Infectious
Diseases, Ulan-Bator, Mongolia
– D.Abmid
• National Center for Natural Foci
Infectious Diseases, Ulan-Bator,
Mongolia
– D.Tserennorov
– D.Batjav
– D.Otgonbaatar
• JSC “Vector-Best”, Novosibirsk
– M.P. Grishaev
• Research Institute of Epidemiology
and Microbiology, SB RAMS,
Vladivostok
– G.N. Leonova
• Khasan Natural Park, Primorye
Region
– E.V. Radiulov
Many thanks for your attention !