Microbiology - Viral Infections (w21) Flashcards
How do viruses cause disease ?
- Infect their specific host’s cells
- replicate efficiently within the host
- damage targeted tissues
What is viral pathogenesis ?
the process of a virus producing a disease
What are 3 requirements for successful infection ?
- Enough virus
- Accessible Cells that permits the viral replication
- Local antiviral defense/immune system absent or overcome
What is a sign ?
Evidence of disease that can be observed by others
What is a symptom ?
Apparent only to the patient
What are acute infections ?
- display short incubation periods upon virus entry into the host.
- Rapid onset of disease
- Brief period of sympthoms
- Quick resolution (elimination of virus by the immune system)
Why is reinfection possible ?
It is possible reinfection as the immune response triggered is not long-lasting and the virus rapidly change
What is a latent virus ?
Latent virus = remains in asymptomatic host cell for long periods
- No symptoms or viruses are detectable/active
- May reactivate due to changes in immunity
- Cold sores (e.g. herpes simplex virus, HSV-1), shingles (varicella zoster virus, VZV)
What is the name for viruses that are known to cause cancer ?
oncoviruses
What are the different systems used to propagate viruses ?
- Animals (used only before the tests of drugs/vaccines on humans)
- Embryonated eggs
- Cell cultures
What is predominantly used to prevent viral infections/severe diseases ?
Vaccines
What are the three stages in which HIV infection progresses ?
1) Acute HIV: flu-like symptoms that occur days to weeks after contracting HIV.
2) Chronic HIV: the latent and asymptomatic stage that can last several years.
3) AIDS: occurs when CD4 cell count falls below 200 cell/mm3. This makes people vulnerable to opportunistic infections and AIDS-defining conditions.
