MCM 2-24 Viral Pathogenesis Flashcards Preview

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Flashcards in MCM 2-24 Viral Pathogenesis Deck (44)
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1

difference between +ssRNA and mRNA

sometimes they are the same. mRNA needs cap and poly-A tail to be recognized by a ribosome

sometimes a +RNA must get changed to -RNA first by RDRP, then trascribed into mRNA for the ribosomes

2

fomites

inanimate objects that have pathogens on them (counters, handles)

3

susceptibility and severity of viral disease depends on

if it is the correct

exposure route
dose
the status of the person
virus-host interaction - unique genetic features of the person and that viral strain

4

two viruses that can enter the body through a scratch

HSV1/2 and HPV

5

describe the epithelial anatomy of the respiratory tract

covered in mucus, ciliated cells and goblet cells with basement membrane (barrier to some viruses). Polarized - the apical is unlike the basal

some viruses enter/leave through the apical (flu)

other enter apical and can pass through the basal membrane

6

What do M-cells do? How are they effected by some viruses?

M-cells sample the gut contents and present to underlying immune cells.

Some viruses can infect M-cells and easily reach the blood stream.

7

describe the common features of Reo and Roto-virus

both unenveloped, get sampled by M-cell and can make it across into the blood stream quickly.

8

Rotovirus

transmission route
Virulence factor?
Immunity is mediated by?
important features?
Types?

tranmission is fecal oral


virulence - nonstructure protein 4 (toxin) nsp4 - effects enterocytes causing massive diarreah

immunity is mediated by IgA by prior exposure OR oral vaccine

Important features - there is a vaccine, this is not a summer disease, very little dissemination - "straight shot through"

type a - under 2 years
type b - over 2 years

9

what is "dissemination" of a virus?

when the virus crosses the basement membrane of the body

10

describe primary viremia

"viruses may spread form the surface of the body to lymph nodes and blood stream"
"primary viremia leads to replication in internal organs, may occur without symptoms (incubation stage)

first appearance of virions in blood. May not be replicationg, but ability to detect virus in blood at low levels.

11

any virus that interacts with the respiratory or gut epithelium requires

attatchment and receptor engagement

(recognition and attachment)

12

What is secondary Viremia?

the virus disseminates to the virus to organs where it is shed
-trasmission may be by direct contact or through environment
-exposure to infected blood is now a common route of transmission

13

describe chicken pox

very contagious via respiratory and eyes

replicates in upper airway, travels to lymph nodes and infects T-cells to spread throughout body

-maintained in dorsal root ganglia for life
-virus always detectable in the blood

vaccines for zoster and varicella, some antivrials but they are not very effective

14

where are the highest levels of HIV found an in infected person?

blood plasma, lymphocytes, CSF, ear secretions

15

virus infection may be...(5)

unnotticed, cause illness, induce autoimmunity, be persistent, or be lethal

16

a successful virus will..

avoid destruction by the immune system and avoid destroying the host before replication is complete

17

Persistent Vs Latent

Persistent - you are able to culture virus in the absense of disease

latent - cannot culture virus in absence of disease

acute - virus goes away

18

5 patterns of viral infection

Acute, Chronic (persistent, latent, slow), transforming

19

infection pattern of

common cold

measles, SSPE

varicella-zoster

hep-B

HIV

Creutzfeld-Jacob

cold = acute

measles = acute infection with rare late complications

zoster - latent

hep-b = chronic with early disease episode

HIV=chronic infection with late disease episode, different acute episode

slow infection - general increase to a disease episode

20

Symptoms of viral disease includes

fever, tissue damage, rash, aches, pains, nausea = mainly caused by the HOST response to infection (mainly interleuken)

21

cell injury is caused by

directly by viruses, indirectly by host reaction

22

Norwalk Virus

transmission
Distribution
At risk
vaccine/treatment
prevention

fecal oral form contaminated water/food

no seasonal incidence

children, schools, resorts, cruise ships

no vaccines

treat with hydration

prevention = handwashing

23

Describe synctium

A direct effect causing cell damage induced by virus

cell inactivation by a virus causing cells to fuse together and lose function

infected cells susceptible to apoptosis

caused by RSV in respiratory tract (Respiratory Syncytial Virus)

24

Immunopathology

Indirect response, Host immune response to virus may cause the disease/injury

-ussually caused by T-cells and immune complexes

-May be made worse with vaccination

ex) herpes stromal keratitis - cause by effect of t-cell intervention of a frequent herpes reactivation in the eye

25

common routes of viral entry

mainy viruses enter through facial passageways including conjunctiva (eye membrane), mouth, and mucous membranes.

26

in the respiratory tract, viruses attatch to the...

mucous layer, from there they interact with the ciliated epithelial cells of the brush border and remain there to either

replicate

cross the basement membrane and penetrate the lymph and blood systems

27

dissemination

Viruses may spread from the surface of the body to lymph nodes via an immune cell. From there, it can reach the bloodstream for the first time. This is referred to as primary viremia (first appearance of virus in the blood…usually at a very low level

28

secondary viremia

fter replication in internal organs occurs, the virus can reenter the bloodstream (secondary viremia). During secondary viremia, the level of circulating virus is much higher, and symptoms usually emerge (end of incubation phase). From secondary viremia, the virus disseminates to the organs where it is shed.

29

transmission

After secondary viremia, the virus may be transmitted by direct contact, the environment, or the blood.

30

Acute

Phases of virus amplification, disease episode, shedding period, and total clearance of the virus.

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