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Arbovirus
Arbovirus
• viruses from various families which are
transmitted via arthropods from one
vertebrates to another.
• Diseases caused by arboviruses
– Encephalitis
– febrile diseases
– hemorrhagic fevers
Flaviviridae Family
Encephalitis B virus
Dengue virus
Forest encephalitis
virus
Epidemic
encephalitis B
fever,
hemorrhagic
fever
Forest
encephalitis
Asiasubtropic or
tropic regions
Mosquito
Worldwide –
tropic regions
Mosquito
Worldwide
Tick
Xinjiang,
China
Tick
Bunyaviridae Family
Xinjiang hemorrhagic
fever virus
Xinjiang
hemorrhagic
fever
Encephalitis B virus
• Japanese encephalitis virus
• Epidemic encephalitis B
Biological Properties
•
•
•
•
•
•
30-40nm
+ssRNA
envelope
icosahedral
only one serotype
E protein
Epidemiology
• Source
– Mosquito and livestocks
• Vector
– mainly Culex tritaeniorhynchus
• epidemic region
– sub-tropic and tropic of Asia
Encephalitis B virus
pathogenicity
• Pathogenesis
– Two viremia
• Clinical findings
– subclinical infections
– Acute encephalitis
Prevent and Treatment
• Prevention
– Vector control
• Avoid being bitten by mosquito
• Eliminating all Culex breeding places
– vaccination
• man
• Animal resovior
• Treatment
– no
Dengue Virus
• Flaviviridae
• Flavivirus
• four virus serotypes
Pathogenicity
• Source
– human and primate
• Vector
– Mosquito
• Occurrence
– world wide---tropic or subtropic areas
• Transmission
– two viremia
Aedes aegypti Mosquito
Pathogenicity
• Clinical Findings
– dengue fever (DF)
– dengue hemorrhagic fever/dengue shock
syndrome (DHF/DSS)
– Hypothesis on Pathogenesis of DHF
• Antibody-dependent enhancement (ADE)
Homologous Antibodies Form
Non-infectious Complexes
Dengue 1 virus
Neutralizing antibody to Dengue 1 virus
Non-neutralizing
antibody
Complex formed by neutralizing antibody
and virus
Heterologous Antibodies Form
Infectious Complexes
Dengue 2 virus
Non-neutralizing antibody to Dengue 1
virus
Complex formed by non-neutralizing
antibody and virus
Heterologous Complexes Enter More
Monocytes, Where Virus Replicates
Dengue 2 virus
Non-neutralizing antibody
Complex formed by nonneutralizing antibody and
Dengue 2 virus
Dengue virus
皮
下
出
血
hantavirus