Flaviviruses

Hugh B. Fackrell

Dept of Biological Sciences

University of Windsor

Windsor ON Canada

Fackrel@Uwindsor.ca

Flaviviruses

• Structure

• Classification

• Multiplication

• Clinical manifestations

• Epidemiology

• Diagnosis

• Control

Baron’s Web site

Flavivirus: Structure

PPT Slide

Flavivirus: Classification

• all Flaviviruses share a common antigen
  • Envelope glycoprotein
  • Hemagglutinin

• 65 different types of flavivirus

• one-third human pathogens

• several antigenic subgroups
  • mite borne
  • tick borne

Flavivirus: Multiplication

• Replication in cytoplasm

• virions assembled in golgi and Smooth ER

• Transported by vesicles to plasma membrane

• Virus RNA acts as mRNA
  • capped, no poly A tail
  • mRNA -> protein
  • mRNA-> antisense RNA
  • Antisense RNA -> sense RNA

Flavivirus: Clinical manifestations

• Encephalitis
  • St. louis encelphalitis, Japanese encephalitis, Powassan, tick borne encephalitis

• Febrile illness with rash
  • dengue virus

• Hemorrhagic fever
  • Kyasanur Forest virus

• Hemorrhagic fever with hepatitis
  • yellow fever virus

PPT Slide

Dengue virus

PPT Slide

Flavivirus: Epidemiology

• endemic areas

• tick-vertebrate-tick cycle

• mosquito-vertebrate-mosquito cycles

• humans intermediate host for yellow fever and dengue

• human infections seasonal

Flavivirus: Diagnosis

• clinical manifestations

• known risk of exposure

• isolation of virus

• increase in IgM
  • minimal value if repeat infection

Flavivirus: Control

• reduce mosquito vector

• yellow fever attenuated vaccine

• Japanese encephalitis - inactivated virus

• tick borne encephalitis- inactived virus