Chapter 29 Arbovirus (Arthropod-borne virus)

1
Chapter 23
Arbovirus Hemorrhagic Fever Virus
??????????
2

Arbovirus
?????????? p302?

• Arbovirus of prevalence in China
  
• ---classified as
  Flavivirus

????????????????????????

• Common characteristics

?Small spherical particle(40-70nm), ssRNA,
icosahedral nucleocapsid, envelope and spike
?Feature of diseases caused by Arbovirus
arthropod----both vector and reservoir hosts of
virus transmitted by bite of arthropod

obvious season and district
clinical
manifestations (?????????)
???????? ????????
3

Encephalitis B Virus
??????
also called Japanese encephalitis virus(JEV)
the most common cause of epidemic encephalitis
4
1. Biological Properties
? Typical flavivirus both in structure and in
shape ? Structural proteinC,M and E
protein(hemagglutinin)
ss-RNA
?????????????(PH6.0)
(??????RNA ? 20?????????)
? Cultivation
suckling mice
embryo-eggs cell
culture(C6/36 cell)


? Antigenicity
(single and stable)
5
2.Pathogenicity and Immunity

? Natural cycles of JEV
??????
bite
mosquito domestic animal
or birds
domestic animal mosquito or birds
(young pigs)
(culex)
ova
(viremia) ????
bite
bite
human
vector of transmission and reservoir source
of infection route of transmission
---?????
?? ,??
---??
epidemic season and district
6
? JEV-infection
(neurotropic virus?infection of CNS)

• Asymptomatic infection
• Abortive infection
• Cause epidemic encephalitis B (0.1)

? Immunity
(IgM?IgG)
---long-lasting immunity
7
3.Laboratory Diagnosis

• ? Isolation of virus (cell culture)
  ? Serological diagnosis

---detection of specific IgM by antibody
cupture-ELISA (ACELISA)
??????gt90
4. Prevention

• ? Cut off the route of transmission
• ? Artificial active immunity
• ? Vaccination of the young pigs

(vector control)
(inoculate live or killed vaccines)
8

Dengue virus
????
(pathogen of dengue fever)
9
1.Biological properties
?Shape and structure(similar to JEV)
?Cultivation ?4 serotypes (??????)
(C6/36????,????)
2. Pathogenicity
?Natural cycle of virus

human(monkey)?mosquitoes?Human (monkey)
vector---- aedes source of infection and
reservoir of virus

510?310?
????( ?????, ??) ????(???, ??)
??????
(????)

10
?Dengue virus -infection

• route of transmisson
• primary infection?dengue fever
• reinfection?dengue hemorrhagic fever(DHF)
  or dengue shock syndrome (DSS)
• pathogenesis of DHF/DSSADE(antibody-dependent
  enhancement)

3.Laboratory diagnosis
? Detection of specific IgM (ELISA) ?
Isolation of virus
? Detection of viral RNA
11
??
Forest encephalitis virus
(??????)
---??????(???????????),?????????,??????????????(??
?????)
12
Hemorrhagic Fever Virus

• important pathogens of causing hemorrhagic fever
  (p306 Table 23-2)
• Hemorrhagic fever of prevalence in China
  

1.hantavirus 2.Xin-jiang hemorrhagic fever
virus 3.dengue virus
13
?. Hantavirus
1. Biological properties
G1
?Shape and structure
G2
round or elliptic virus envelope with HA
?????? PH6.06.4
?Genome
d120 nm
--- segmented -ssRNA (L,M and S)
polymerase
G1,G2
?Cultivation
N
(Cell culture and susceptible animal)
?Epidemic serotype in China
Hantaan virus (????,???) Seoul virus
(????,????)
14
2.Pathogenicity and Immunity
? Epidemiology
???? ??? ???
??? ???
?????? (?/?/??)

• source of infection
• mode of transmission
• mite
• obvious season and district

(????)
(?, both vectors and reservoir)
? Clinical syndromes
hemorrhagic fever with renal syndrome
(HFRS,???????) Hantavirus pulmonary
syndrome
(HPS,????????)
??????(EHF)
? Immunity
(long-lasting immunity)
15
3.Laboratory diagnosis
and prophylaxis

• ? Laboratory diagnosis
  ---isolation of virus, detection of viral Ag and
  specific IgM or of viral RNA
• ? Prophylaxis

16
2.Pathogenicity
?.XinJiang Hemorrhagic Fever virus
1.Properties of XHFV
(similar to hantavirus)

• ? Source of infection
• ? Route of transmission
• ? Cause XinJiang Hemorrhagic Fever

???????
(by bite of hard tick with viruses)

???????
3. Immunity
---long-lasting immunity