Flaviviruses Hugh B. Fackrell Dept of Biological Sciences University of Windsor Windsor ON Canada

Flaviviruses  Structure  Classification  Multiplication  Clinical manifestations  Epidemiology  Diagnosis  Control Baron’s Web site Baron’s Web site

Flavivirus: Structure

Flavivirus: Classification  all Flaviviruses share a common antigen ä Envelope glycoprotein ä Hemagglutinin  65 different types of flavivirus  one-third human pathogens  several antigenic subgroups ä mite borne ä 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 ä capped, no poly A tail ä mRNA -> protein ä mRNA-> antisense RNA ä Antisense RNA -> sense RNA

Flavivirus: Clinical manifestations  Encephalitis ä St. louis encelphalitis, Japanese encephalitis, Powassan, tick borne encephalitis  Febrile illness with rash ä dengue virus  Hemorrhagic fever ä Kyasanur Forest virus  Hemorrhagic fever with hepatitis ä yellow fever virus

Dengue virus

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 ä minimal value if repeat infection

Flavivirus: Control  reduce mosquito vector  yellow fever attenuated vaccine  Japanese encephalitis - inactivated virus  tick borne encephalitis- inactived virus