Togaviruses & Flaviviruses

Question 1

Structure

Answer 1

enveloped +ssRNA
Icosahedral capside
45-75 nm

Question 2

Togaviruses

Answer 2

Alphaviruses (arthropod-spread encephalitis)

Rubivirus (rubella)

Question 3

Flaviviruses

Answer 3

Alphaviruses (dengue, yellow fever, west nile, Zika, anthropod diseases.)
Hep C

Question 4

pathogenesis

Answer 4

bite of an arthropod, e.g. mosquito. Lytic or persistent infections
FEMALE mosquitos. circulates in hosts plasma. infects endothelial cells of the capillaries + monocytes,macrophages dendritic cells

Question 5

4 Phases + symptoms

Answer 5

Initial viremia - fever, chills, headaches, backaches, (flu-like) (most infections do not progress beyond here)
Secondary viremia - can infect target organs depending on tropism of virus
Brain infected - via endothilial cells lining vessels of brain
Hemorrhagic disease and shock - viral and immune cytolysis of infected vascular endothelial cells, + cytokine storm.

Question 6

Immune response

Answer 6

IFN-a IFN-B
IgM for first week then IgG
immune response is important for resolution but exacerbates immunopathogenesis

Question 7

Epidemiology

Answer 7

virus must stay wet, can be inactivated by drying,soap, detergents
Spread by arthropods

Question 8

Control

Answer 8

Kill mosquitos
No treatments
Live attenuated vaccines

Question 9

Diagnosis

Answer 9

RT-PCR for viral mRNA

monoclonal antibodies for distinguishing species/strains