Viral Pathogenesis Flashcards Preview

Disease & Defense - Unit 3 > Viral Pathogenesis > Flashcards

Flashcards in Viral Pathogenesis Deck (20):
1

Common routes of infection and initial sites of replication

-common routes: respiratory, alimentary, or genitourinary tract
-replication: epithelial cells near body surface/barriers

2

Enterotropic virus definition

replicates in the gut

3

Neurotropic virus definition

replicates in the nervous system

4

Factors that determine tropism

-access to desired tissue
-receptors required for virus binding/entry
-expression of host genes required for virus infection and replication
-relative failure of host defenses

5

Tissue tropism affect on viral development

can drive population variant among or within individuals; particularly in viruses w/highly error-prone replication systems

6

Transmission and shedding definition

release of infectious particles from an infected host

7

Site of shedding for local infections

occurs from the site of initial infection

8

Site of shedding for disseminated/systemic infections

-multiple or distant sites possible

9

Fomite definition

virus-associated objects

10

Types of viral transmission

-single susceptible host vs. alternate infection of one host w/another (e.g. insect to human)
-close contact (e.g. enveloped viruses)
-fomites (e.g. hardier, non-enveloped viruses)
-usually horizontal, but may be vertical/germ-line

11

Immune-mediated pathology associated with viruses

-IMP=viral disease as a result of host immune response to infection
-antibody-mediated (immune complexes)
-cell-mediated (rash, fever, malaise)
-autoimmunity (cross-reactivity)
-immune modulation/suppression

12

Acute local viral disease: 1. first site of replication 2. viremia 3. secondary replication 4. site of symptoms 5. incubation period 6. duration of immunity 7. Ab responsible for resistance 8. example

1. epithelium
2. no
3. none
4. entry epithelium
5. 1-3 days
6. often short
7. secretory IgA
8. common cold

13

Persistent chronic viral infection

-viral infection that continue to produce new virus over long period of time
-result of acute primary infection that is not cleared OR
-virus retains ability to transmit to other organisms or host offspring

14

Latent chronic viral infection

-substantial periods in which the host produces no detectable virus
-little or no disease in healthy host
-viral genome is silent
-retain the ability to re-initiate transcription and replication to produce new virus

15

Acute systemic viral disease: 1. first site of replication 2. viremia 3. secondary replication 4. site of symptoms 5. incubation period 6. duration of immunity 7. Ab responsible for resistance 8. example

1. epithelium
2. yes, primary and secondary
3. lymphoid organs, lung, skin
4. systemic
5. 10-21 days
6. usually lifelong
7. serum IgG and secretory IgA
8. measles

16

Slow chronic viral infection

-no symptoms on initial infection
-long incubation period
-may or may not induce immune response
-eventual disease followed by progressive deterioration and death

17

Examples of viral diseases: 1. Acute local 2. Acute systemic 3. Chronic 4. Latent 5. Slow/progressive

1. colds, diarrhea 2. smallpox, measles 3. Rubella in neonate 4. VZV in nerves 5. AIDS, canver

18

General characteristics of chronic viral infection

-ongoing virus infection/replication
-mild or inapparent disease in healthy host
-manifestation of disease often coincides w/immune suppression

19

Host factors in susceptibility to viral disease

-receptors for virus entry, accessibility and permissivity
-age of host
-genetic background
-immune status

20

Types of virulence genes (4)

1. affect ability of virus to replicate
2. modify host defense mechanism
3. facilitate virus spread in and among hosts
4. directly toxic to host cells