L7 - Mechanism of Viral Infection and Pathogenesis Flashcards
What is Acute viral infection and describe its pattern of infection?
acute infection is something that has a limited lifespan
Usually virus load and disease symptoms peak at one point and then drop
What are some Acute viral infections?
common cold
measles
ebola
small pox
What is Latent reactivating infection and describe its pattern of infection?
It is a chronic infection
Virus load may increase and with treatment decrease, however it still comes back throughout life, sometimes presenting disease symptoms, and sometimes not.
What are some Latent reactivating infections?
Herpes simplex virus type 1 Herpes simplex virus type 2 Epstein Barr virus Varicella zoster Human Herpes virus 6 Human Herpes virus 7 Human Herpes virus 8
What are some disease symptoms of Herpes simplex Virus?
Early life = Primary Gingivostotamitis
Later life = cold sore
What are some disease symptoms of Chicken pox/Varicella zoster virus?
early life = pox marks
later life = shingles
What is Persistant infection and describe its pattern of infection?
Persistance of a virus in the presence of an active immune response.
Viral levels are constantly controlled by active host immunity
What are some Persistant infections?
HIV - retrovirus
HCV - flavivirus
Measles
Congenital Rubella (not controlled by immune system)
Describe Congenital Rubella as a Persistant infection?
Congenital Rubella; if infected in utero, virus is seen as self, baby is born immunotolerant and virus continues to replicate (and cause damage) in neonatal tissues
Rubella virus viremia can infect the placenta of pregnant women, and viral replication can infect all foetal organs. Causes huge amount of tissue damage
Why is it advantageous for a virus to be asymptomatic?
If the host becomes ill, there is a lower chance that the virus will be able to spread and replicate in another host.
How does virus infection of a host lead to disease?
Pathogenesis results from cell and tissue damage caused by the viral infection. On most occasions the damage is limited by the host’s immune system
What is meant by a non-cytopathic infection?
One that does not cause pathological or structural changes in the host cell.
Give an example of a Cytopathic Infection?
Ebola
Describe Ebola as a Cytopathic viral infection?
Causes massive Haemorrhagic fever and targets vascular endothelial cells, and destroys them.
The endothelia rupture and release their contents which is usually fatal.
Describe Influenza A virus as a Cytopathic viral infection?
Targets lung epithelia.
Influenza A destroys the ability of the cilia on the epithelial cells, so they cannot beat away debris and mucus from the lungs anymore.
As a result the lung tissues become flooded, leading to viral pneumonia
