Exam 1: Mechanisms of Infection Flashcards

1
Q

What viruses use the minor abrasion route?

A

Family: poxviridae

Cowpox, orf

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2
Q

What viruses use the arthropod (mechanical) route?

A

Family: poxviridae

Fowlpox, swinepox

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3
Q

What viruses use the arthropod (biological) route?

A

Family: rhabdoviridae

Bovine epheremal fever

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4
Q

What viruses use the bite of vertebrate route?

A

Family: rhaboviridae

Rabies

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5
Q

What viruses use the genital tract route?

A

Family: herpesviridae

Many species

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6
Q

What viruses use the conjunctiva route?

A

Family: adenoviridae

Canine adenovirus 1 and 2

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7
Q

What viruses initiate infection in the respiratory tract?

A

Adenoviridae and herpesviridae: many species

Parvoviridae: feline panleucopenia virus, canine parvovirus

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8
Q

What viruses produce respiratory disease?

A

Adenoviridae and herpesviridae

Many species

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9
Q

What viruses produce systemic disease, usually without initial respiratory signs?

A

Parvoviridae

Feline panleucopenia virus, canine parvovirus

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10
Q

What viruses initiate infection in the intestinal tract?

A

Coronaviridae and toroviridae: some coronaviruses, Breda and Berne viruses
Calciviridae and picornaviridae: vesicular exanthema of swine virus, some enteroviruses

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11
Q

What viruses produce diarrhea?

A

Coronaviridae and toroviridae

Some coronaviruses, Breda and Berne viruses

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12
Q

What viruses produce systemic disease, usually without diarrhea?

A

Calciviridae and picornaviridae

Vesicular exanthema of swine virus, some enteroviruses

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13
Q

What are the mechanisms of spread in the body?

A

Local spread on epithelial surfaces
Subepithelial invasion and lymphatic spread
Spread by the bloodstream: viremia

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14
Q

Describe local spread on epithelial surfaces with pox virus

A

Produce infection via the skin

Local subepithelial and lymphatic spread

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15
Q

Describe local spread on epithelial surfaces with paramyxoviruses and influenza virus

A

Do not invade subepithelial tissues

Enter lymphatic and spreaf

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16
Q

Describe local spread on epithelial surfaces with rotaviruses or coronaviruses

A

Do not invade subepithelial tissues

Enter lymphatic and spread

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17
Q

Where does canine distemper virus replicate?

A

Macrophages

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18
Q

What is the most important route for virus shedding?

A

Respiratory secretions

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19
Q

Which viruses have virus shedding in the skin?

A

FMD
Vesicular stomatitis
Pox
Herpes

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20
Q

What viruses have virus shedding in saliva?

A

Rabies and feline immunodeficiency viruses

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21
Q

What viruses have virus shedding in feces?

A

Poliovirus and rotaviruses

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22
Q

What viruses have virus shedding in genital secretions?

A

Herpes and immunodeficiency viruses

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23
Q

What viruses have virus shedding in urine (viruses that replicate in the kidney)?

A

Rinderpest
Infectious canine hepatitis
FMD

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24
Q

What viruses have virus shedding in milk (replicate in mammary gland)?

A

Caprine arthritis-encephalitis

Tick-borne flaviviruses

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25
Q

What happens to viruses that don’t shed?

A

Replicate in CNS

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26
Q

What viruses shed in the respiratory tract mucous membrane?

A

Canine distemper

Rinderpest

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27
Q

What viruses shed in the skin?

A

Lumpyskin disease

28
Q

What viruses are in the brain, but no shedding?

A

Arbovirus

Canine distemper encephalitis

29
Q

What viruses shed in the salivary gland or kidney?

A

Rabies (salivary gland only)
Arenaviruses
Cytomegaloviruses

30
Q

What are persistent infections?

A

Infection that persist for the life of the animal, although episodes of clinical disease might occur infrequently

31
Q

What are examples of persistent infection?

A

Classical: herpesvirus
Unclassical: canine distemper virus

32
Q

Why are persistent infections are important?

A

Serves as a source of infection for other animals
Can be reactivated and cause recurrent acute episodes of disease
Lead to immunopathologic disease
Associated with neoplasms

33
Q

What are latent infections?

A

Virus is not demonstrable except when reactivation occurs

34
Q

What are chronic infections?

A

Virus always demonstrable and often shed and disease may be absent, chronic, or may develop late

35
Q

What are slow infections?

A

Virus gradually increases during a very long preclinical phase, leading to a slowly progressive lethal disease

36
Q

Where does the viral genome for infectious bovine rhinotracheitis virus persist?

A

Latently in neurons, probably as an episome

37
Q

What happens when the episome for infectious bovine rhinotracheitis virus reactivates?

A

Infectious virus is produced and moves down the sensory nerves and reaches the nasal mucous membrane or the skin

38
Q

Where does proliferation of infectious bovine rhinotracheitis virus occur?

A

Epithelial cells, with virus shedding

39
Q

What is an episome?

A

Like an extracellular plasmid

40
Q

What does FMD persist in?

A

The pharynx in cattle, sheep, goats, and other ruminants

41
Q

What is lymphocytic choriomenigitis in mice caused by?

A

Arenavirus

42
Q

How is lymphocytic choriomenigitis in mice transmitted?

A

Horizontally and in utero

43
Q

What is vertical transmission?

A

Offspring becomes immunologically tolerant (in presence of virus but in absence of antibody)

44
Q

What is immunological tolerance (incomplete)?

A

The presence of virion-IgG-complement and the complexi is infectious

45
Q

What is subacute spongiform viral encephalopathies?

A

Scrapie in sheep and goats

Bovine spongiform encephalopathy (Mad cow)

46
Q

What are prions?

A

Proteinaceous infectious particles

Misfolded protein that concentrates in the tissues of CNS

47
Q

Where do prions concentrate?

A

In brain and spinal cord

48
Q

What are prions resistant to?

A

Steam sterilization

49
Q

What do prions do?

A

Persuades other proteins to copy it

50
Q

What is canine distemper?

A

Acute systemic infection in which the majority of dogs recover completely within 1 month

51
Q

What can happen with dogs that have recovered from canine distemper?

A

They can harbor the virus in brain cells where it replicates slowly and eventually produces old dog encephalitis

52
Q

What is the pathogenesis of persistent infections?

A
Unique properties of the virus:
Nonimmunogenic agents
Integrated genomes
Growth in protected sites
Antigenic variation
53
Q

Describe nonimmunogenic agents-prions

A

Do not induce interferon

No immune responses, therefore host cannot restrict the replication and pathologic effects

54
Q

What are integrated genomes?

A

Retroviruses whose proviral DNA is integrated are maintained indefinitely, from one generation to the next, as a part of the genome of the host

55
Q

Describe how alphaherpeeviruses grow in protected sites

A

Avoid immune elimination by remaining within cells of the nervous system
As episomal DNA in ganglion cells during the intervals between disease episodes
As viral DNA, subviral particles, or virions within axons prior to acute recurrent episodes

56
Q

Describe how betaherpeeviruses and gammaherperviruses grow in protected sites

A

Avoid immune elimination by maintaining serial infection by cell-to-cell contact

57
Q

What are mechanisms of modification of host defense?

A

Defective antibody response
Defective cell-mediate immunity
Growth in macrophages

58
Q

In defective antibody responses, what do viruses that replicate in lymphoid tissue and macrophages do?

A

Induce non-neutralizing antibodies

59
Q

What does the antibody do in defective antibody response?

A

Combines with viral antigens and virions in the serum to form immune complexes which may produce immune complex disease

60
Q

What do viruses in macrophages do?

A

Avoid host immune responses

61
Q

Describe defective cell-mediated immunity

A

Immunosuppresion by the causative virus
Immunological tolerance
The presence of virus-antibody complexes
Filaure of immune lymphocytes to reach target cells
Decrease in the numbers of Th lymphocytes

62
Q

What is the target of receptor analogs?

A

Attachment of virion to cell receptor

63
Q

What is the target of transcriptase inhibitor?

A

Primary transcription

64
Q

What is the target of AZT?

A

Reverse transcription

65
Q

What is the target of interferons?

A

Translation of viral mRNA into protein

66
Q

What is the target of protease inhibitors?

A

Post-translational cleavage of proteins

67
Q

What is the target of replicase inhibitors?

A

Replication of RNA viral genome