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Flashcards in Host Defenses Deck (17):

What is the role of innate immunity?

Early defense
No memory
Many pathogens have resistive mechanisms (parasites)


What is the role of adaptive immunity?

Longer to develop
Antigen specific
Memory Response
Optimal type of immune response for a pathogen


What viruses primarily enter through the skin?

HepB/Papilloma v (minor breaks/cuts)
Rabies (Animal Bites
West Nile Virus (Mosquito bite)
HIV/Hep B/C (injection)


What viruses primarily enter through the ailmentary tract?

(naked viruses can survive bile better)
HSV 1/EBV (mouth)
Hep A/Rotavirus/Poliovirus (GI)


What viruses primarily enter through the Resp Tract??

(Resp tract bugs have trouble surviving in the GI tract) Adenovirus/Rhinovirus (URT, local)
Influenza/RSV (LRT, local)
Measles/mumps/rubella/varicella (local infection, systemic dx)


What viruses primarily enter through the conjunctiva?

Adenovirus/Enterovirus (direct contact)


What are the cellular forms of Innate immunity against viruses?

Inteferon a and B (Type 1 interferon)
Natural Killer Cells


What are the effects of the Interferons?

Produced by virus INFECTED host cells
Inhibit viral replication in surrounding UNINFECTED host cells
Leukocytes => Produce interferon alpha
(Fibroblasts + other non leukocytes produce INF-B)
Activate dendritic cells and macrophages
Activate NK cells


What are the Attributes of Natural Killer Cells?

Lyse Virus infected cells early in virus infection

Some viruses dec prod of MHC1 to avoid lysis by CTLs

NK cells are activated by ABSENCE of MHC 1

NK cells enhanced by the interferons


What kills virus infected cells if MHC1 is present?
Not present?

CD8+ T cells (Cytotoxic Lymphocytes, CTLs)

Natural Killer cells


What is the role of NK cells

Mediate ADCC
Crosslinking of IgG Fc receptors triggers ADCC
Kill via Apoptosis and perforin mediated osmotic death


How can macrophages fight/help Viruses?

Produce TNF-a and NO => interfere with virus replication
Can be infected by viruses( CMV, Ebola, HIV, MEasles, rubella
Traffic to many body sites (FACILLITATES virus spread)


What are the functions of Antibodies?

Prevent virus from binding a target host cell
Opsonize virus (phagocytosis)
Activate compliment (lyse viral
Facilitate ADCC by NK cells
Downreg. expression of viral genes inside infected cells


What are strategies of Evasion of immunity?

Alter anttigen through point mutation
Prevent MHC1 mediated expression of viral peptides
HIV infects/kills CD4+ T cells


What are deletrious effects of the immune response?

Hep B = Liver damage
Chronic infection => Immune complex disease
Molecular mimicry(viral cells can express proteins similar to normal tissue)


How are Macrophages activated by NK cells?

Macrophage produces IL-12
in response NK cell produces IFN-y to activate Macrophages


How are granulomas formed?

Th1 mediated response triggered by release of IL-12 by macrophages after microbial invasion (IL-4 steers response toward TH2)