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RUSVM Virology > Virus Pathogenesis > Flashcards

Virus Pathogenesis Flashcards

1
Q

T/F: Virulence is an absolute property of a virus, regardless of any variables.

A

FALSE - depends on many things!

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2
Q

The dose of virus needed to cause death or infection in 50% of test subjects is known as:

A

LD50

ID50

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3
Q

Will a more virulent virus have a higher or lower LD50 or ID50?

A

Lower - takes less virions to do the same job

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4
Q

Steps in viral infection

A 
Entry and replication
Spread, tropism, infection of target organs
Virus-cell interactions
Tissue and organ injury
Shedding
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5
Q

What are the skin’s defenses against infection?

A 
Dense keratin layer
Low pH
Fatty acids
Normal flora
Dryness
Immune cells
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6
Q

Transcutaneous routes of pathogen entry

A

Arthropod bite
Bite of infected animal
Contaminated objects (needles)

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7
Q

What are the GI tract’s defenses against infection?

A 
Mucous
Stomach acidity
Intestinal alkalinity
Bile and Pancreatic enzymes
Defensins/ IgA/Macrophages
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8
Q

What are the respiratory tract’s defenses against infection?

A

Mucous
Alveolar macrophages
NALT/BALT
Temperature gradient

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9
Q

What type of infection spreads beyond the primary site?

A

Disseminated

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10
Q

What direction of viral shedding from cells facilitates systemic spread?

A

Basolateral release - gives access to underlying tissues

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11
Q

What direction of viral shedding from cells facilitates virus dispersal?

A

Apical release

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12
Q

________ _______ is the initial entry of the virus into the bloodstream following infection.

A

Primary viremia

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13
Q

______ ______ happens after the virus has replicated in major organs and once again entered the bloodstream.

A

Secondary viremia

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14
Q

________ _______ is a direct inoculation of a virus into the blood, such as by arthropod bite or contaminated syringe.

A

Passive viremia

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15
Q

What are neurotropic viruses?

A

viruses that can infect neural cells

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16
Q

What kind of viruses are able to enter the central nervous system after infection at a peripheral site?

A

Neuroinvasive viruses

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17
Q

What kind of viruses cause disease of nervous tissue, manifested as neurological symptoms and often death?

A

Neurovirulent viruses

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18
Q

If a virus always enters the PNS, but rarely the CNS, and causes severe symptoms/death when it does enter the CNS, it is considered to have ___ _______ but ___ _______.

A

Low neuroinvasiveness and high neurovirulence

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19
Q

If a virus almost always enters the CNS, but rarely causes neurological disease it is considered to have _______ and ____ _______.

A

Neuroinvasiveness and low neurovirulence

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20
Q

If a virus readily spreads from the PNS to the CNS and causes death 100% of the time without prompt antiviral medication it is considered to have ____ ______ and ____ ______.

A

high neuroinvasiveness and high neurovirulence

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21
Q

When a virus travels in the opposite direction of neural impulse flow, from axon terminal to dendrite/cell body, it is called __________ spread.

A

retrograde

22
Q

When a virus travels in the direction of neural impulse flow, from dendrite/cell body to axon terminal, it is called ______ spread.

A

anterograde

23
Q

What are 2 routes a virus can take to spread to the CNS?

A

Olfactory

BBB

24
Q

What type of infection features intensive shedding over a short period of time?

A

Acute

25
Q

In what type of infection does a virus spread at low titers for months or years?

A

Persistent

26
Q

Definition of pantropic virus

A

Virus that can replicate in more than one host tissue/organ

27
Q

Fluid filled sacs or elevations in the skin

A

Vesicles

28
Q

An opening in the skin caused by sloughing of necrotic tissue, extending past the epidermis

A

Ulcer

29
Q

Palpable, solid, elevated mass. Distinct borders and can be extending deep into the dermis.

A

Nodule or tumor

30
Q

Benign skin growths that appear when a virus infects the top layer of skin

A

Warts

31
Q

Solid elevations on the skin without fluid

A

Papules

32
Q

Reddening of the skin (can be a consequence of systemic viral infection).

A

Erythema

33
Q

Gastrointestinal infection can happen via which 2 pathways?

A

Ingestion

Hematogenous spread/systemic infection

34
Q

Effects of viral infection on the intestinal tract

A

Destruction of enterocytes and hyper secretion, leading to GI disease, malabsorption, and diarrhea, causing dehydrating, acidosis, and hemoconcentration.

35
Q

Effects of viral infection on the respiratory tract

A

Loss of ciliary activity and integrity of mucus layer

Destruction of epithelium
Inflammation
Exudation
Influx of inflam cells
Obstruction of airways
Hypoxia/distress
Secondary infection
36
Q

Effects of viral infection on the CNS

A 
Encephalitis
Encephalomyelitis
Neuronal necrosis
Neuronophagia
Perivascular cuffing
Demyelination
Neuronal vacuolation
37
Q

Effects of viral infection on the hematopoietic system

A

Damage to endothelium (hemmorrhage)
Disseminated Intravascular Coagulation
Edema
Infarction

38
Q

What happens during DIC?

A

A bunch of clots form in the small vessels, restricting blood flow and causing multi-organ failure. After that, coagulation factors are all used up which leads to hemorrhage throughout the body.

39
Q

The abnormal development or arrest in development of the embryo or fetus.

A

Teratogenesis

*May lead to death or malformations during the antenatal period.

40
Q

T/F: During the body’s immune response against infection, tissue injury to the host can occur.

A

TRUE - Virus-Induced Immunopathology.

*depends on a balance between the protective and destructive effects of the host immune response

41
Q

What are some manifestations of Immunopathology?

A

Tissue damage d/t hypersensitivity reactions

Autoimmune diseases (moon blindness)

Inflammation-mediated tissue damage (fibrosis)

Immunodeficiency disorders

42
Q

The roll of T cells in virus-induced immunopathology

A

Cytotoxic T cell mediated lysis of infected host cells

Release of cytokines from CD4+ and CD8+, and other cells, that cause inflammation and tissue damage. (Chronic in persistent infections)

43
Q

Role of TLRs in virus-induced immunopathology

A

Persistent activation of these receptors leads to production of pro-inflammatory cytokines and interferons (^^ inflammation)

44
Q

T/F: Production of ROS to combat viral infections will only harm the pathogens.

A

FALSE - ROS can also injure nearby host cells

45
Q

How do antibodies contribute to immunopathology?

A

Binding of Ab to an infected cell activates the complement system and initiates an inflammatory reaction

46
Q

What’s an example of virus-induced immunopathology leading to immunosuppression?

A

Infectious Bursal Dz: viral replication causes atrophy of the Bursa of Fabricius in birds, leading to a deficiency in B lymphocytes.

47
Q

What type of viral infections may not be detected clinically and may lead to spread of the virus?

A

Inapparent infections

48
Q

In what type of infection is the virus not demonstrable except in cases of immunosuppression or cytokine activation when it is reactivated?

A

Latent (persistent) infections

49
Q

Foot and Mouth Dz in cattle tends to stay in and shed from infected tissue after acute disease. This is an example of what kind of infection?

A

Chronic (persistent) infection

50
Q

Prion diseases have a prolonged incubation period that lasts months or years, during which time numbers of infectious particles gradually increase, and eventually cause a progressive lethal disease. This is an example of what kind of infection?

A

Slow (persistent) infection

51
Q

What kind if infection is cleared rapidly by the host immune system?

A

Acute infection

RUSVM Virology (11 decks)

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