Encephalitis
virus
B
黄秦夏姜姜李孙吕吕叶马
俊伟文振
晓钊卓
霞栋君宇蓉艳君鹏珍翔姝
Biological properties
Also called Japanese encephalitis virus
(flavivirus )
+ssRNA
Capsid: Icosahedral symmetry
Enveloped
Three kinds of structural proteins
E the glycoprotein on the surface
of
envelope
M inner surface of the envelope
C the protein of the capsid
Antigenicity stability
Picture of Encephalitis B virus
The course of infection
the bite of an
infected
mosquito
Proliferation in the
endothelium of capillary
and the regional lymph
node
Little into the
blood caused
the first
viraemia
Proliferation in the
mono macrophage of
the spleen and liver
a secondary
viraemia
some cases the virus
crosses the blood brain
barrier
Abortive
infection
Encephalitis
Epidemiology
Source of infection and
reservior host
The major source is domestic
animal、poultry
pig→mosquito→pig
Proliferation in mosquito and
transmit to its eggs.The virus lives in
the mosquito for ever.
Vector
Culex tritaeniorhynchus(三带喙库蚊)、
aedes、anopheles
Susceptible people
The children under 10 years old is
easy to be Infected
Life time long immune to the virus
The Piglet
Characteristics of epidemiology
EB only distributes in Asia.
80～90% case all focus on
July ,August, September.
South china June～July，
north china July～August,
northeast August～ September，
all identical to the density curve of
mosquitoes.
Highly disperse.
Epidemic Region
Encephalitis B
Clinical Manifestation
Light type
38～39℃, always consciousness 嗜睡
commonly no twitch,no evident stimulation to
meninx ,recovery within a week.
Medium type
40℃or so hard to conscious such as light coma ,sometimes
twitch ,last 10days or so .
 Severe type
above 40℃，coma ，persistently twitch ,may cause failure
of respiratory ,manifestation of different extent of mental
disorder and paralysis during recovery.

Break-out type
high fever ever super high fever, deep coma and
repeated strongly twitch,may die due to centrally
respiratory failure during very short time ,even
survivals often have severe sequelae.
coma
above 40℃，coma ，
persistently twitch ,may
cause failure of
respiratory ,manifestation
of different extent of
mental disorder and
paralysis during recovery.
twitch
Immunity
IgM presents 5~7 days later after infection
IgG hemagglutination inhibition antibody
Neutralization antibody
complement fixation antibody（no protection）
Stable immunity，latent infection also can get
the immunity
Microbiological detection
Test for cerebrospinal fluid(CSF)
PCR 100% specific
Isolation and Identification
Necropsy or viral culture using Vero, LLCMK2
and PS cells
Serology test
Source of false positive :heterologous
flaviviral antibody
ELISA
Test specific IgM Ab in serum or
cerebrospinal fluid
Hemagglutination inhibition test
detect IgM antibodes and IgG
antibodies
Neutralizing test
Early stage:IgM later stage:IgG
Complement binding test
 Treatment
No specific treatment Interferon-alpha A
 Mortality
less than 10%
Report
Prevention
Kill mosquitoes
Inoculation of vaccine
live attenuated vaccines
Cell culture-derived inactivated
vaccine (primary hamster kidney cell )
children 6 months----10 years
old in epidemic region.