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25 Cards in this Set

  • Front
  • Back
What is the main consequence of the "Iceberg" concept of viruses?
We may be able to transmit many minor diseases without even knowing we are sick with them.
Can the same virus cause the different symptoms in different parts of the body?
Yes they can, and example is Epstein Barr or Herpes Simplex.
What is THE fundamental property of a virus?
It is an obligate intracellular parasite.
What are six different ways thata virus can get into your system?
1. Respiratory areosols
2. Gut
3. Eye
4. Urogenital Tract
5. Skin
6. Direct innoculation into the blood
What do you call the spectrum of tissues and cell types that a virus can infect?
Viral Tropism
Does the Papilloma virus have a limited tropism or a wide viral tropism?
Limited because it does not spread from tissue to tissue.
What are the five determinants of viral tropism?
1. The host cell must have the appropriate cell surface receptors.
2. Viral fusion proteins must be activated by a particular cellular protease.
3. Temperature
4. pH
5. Once inside the cell, the host cell must have particular cellular factors for viral replication.
What is the most important way a virus spreads inside the host?
What is the release of the virus into the blood after replication at the initial site of entry called?
Primary viremia
What is delayed spread of the virus due to release of the virus from secondary sites of infection?
Secondary viremia
Which viremia typically results in a higher viral load?
Secondary viremia because the infection is more than likely already spread to many sites.
What is required to complete the viral replication cycle?
Viral shedding - the release from the original host to spread to a new host
What innate immune repsonses are seen in an acute viral infection?
1. Type 1 interferons are induced
2. NK cells and macrophages are activated
If an acute viral infection is not cleared by the innate response, what is seen next?
The adaptive immune response is activated including CD4 and CD8 cells. Plasma cells are activated after the induction of the T Cell reponse.
dsRNA induces what?
The release of type 1 interferons (alpha and beta) which inhibit protein synthesis (anti-viral state).
What enzyme is active when dsRNA is present in the cell? What enzyme is activated in reposnse to the previous enzyme being active?
1. 2'-5' Oligodenylate synthetase
2. RNase L - degrades all mRNA in host cell
What enzyme is induced by interferons alpha and beta and how does it cause an anti-viral state?
1. Protein Kinase R
2. It phosphorylates ELF-2
How does the virus being latent enable it to evade the immune system?
Antibodies are not produced against the virus.
What is an example of locations a virus would target to evade the immune system? Why would it target these areas?
1. Eyes, testes, uterus and brain
2. These are immunopriveledged sites that do not have strong immune reactions
What is one of the main ways a virus can evade the immune system. This method is used frequently by the influenza virus.
Antigenic variation
What is the accumulation of point mutations resulting in variant proteins that are no longer recognized by the antibody?
What is the reassortment of entire ssRNA segments between human and animal viruses infecting the same cell?
What is immunogenic exhaustion?
Complete depletion of immunogenic effectory cells due to a chronic viral infection.
What are the types of viral vaccines that are used today?
1. Live viral vaccines
2. Inactivated/killed vaccines
Do all viruses integrate into the host genome?