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Infectious diseases midterm > Lecture 2 > Flashcards

Lecture 2 Flashcards

1
Q

RNA viruses

A

Must encode or carry RNA-dependent RNA polymerase

Replicate in cytoplasm

Often have faster mutation rates than DNA viruses

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2
Q

DNA Viruses

A

Viral genomes stable in cell (persistent infections)

Most occupy nucleus

Temporal control of viral gene expression

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3
Q

Virulence factors (virus-encoded activities)

A

enhance attachment, transmission, replication, evasion of host responses

Attenuated virus – loss of virulence factors

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4
Q

Stages of Viral Infections

A

Acquisition – gain access to body

Initiate primary site infection (often oral or respiratory)
Innate immune response activated (Phagocytes, IFN response)

Incubation period

Spread to secondary site in some cases
Replication in target tissue
Trigger adaptive immune responses
Can be beneficial or develop into immunopathology

Resolution or persistence

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5
Q

Stages of viral Infection part 2

A

Asymptomatic – can progress to 2° site without symptoms

Prodrome – early, non-specific symptoms
(fever, aches, chills) (what is causing the symptoms of prodrome?)

Immune Response – innate immunity can usually resolve; if not, adaptive immune responses are triggered

Convalescence – symptoms from tissue repair mechanisms; development of immunological memory

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6
Q

Viral transmission

A

Inhalation (most common route of entry)
Preferentially infect oral & respiratory mucosa
epithelial cells express viral receptors
possess necessary replication machinery

Gastrointestinal
virus shed in feces (fecal-oral)
M cells in Peyer’s patches

Sexual
Blood
Transcutaneous
Maternal (fetal/neonatal)

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7
Q

Viral Transmissions pt 2

A

Various mechanisms of dissemination from 1° site
local spread

Viremia – in the bloodstream

Within infected leukocytes & lymphocytes

M cells

Into the CNS
Viremia to CSF or meninges, by macrophage migration, or by transmission from infected PNS neurons

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8
Q

Abortive is

A

failed infection

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9
Q

Inapparent

A

asymptomatic (no consequences)

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10
Q

lytic

A

infection kills host cells

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11
Q

non-lytic (persistent)

A

infection does not result in cell death

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12
Q

Chronic

A

non-lytic, productive

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13
Q

Latent

A

non-productive

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14
Q

Recurrent

A

on/off production

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15
Q

Transforming

A

immortalizing

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16
Q

Permissive

A

– allow complete replicative cycle

17
Q

semi-permissive

A

slow, inefficient replication

18
Q

Non-permissive

A

-lack essential machinery or actively block replication or assembly

19
Q

Slide 10 review it

A
20
Q

Lytic infections do what?

A

KILL TARGET CELLS

Produce Cytopathic Effects (CPEs) – induce morphological changes
Inflict damage
Inhibit repair
Inhibit DNA & protein synthesis
Degrade host nucleic acids
Disrupt host cellular functions

21
Q

Non-Lytic Infections

A

Viruses persist intracellularly
(released through exocytosis or budding)

Occur following infection of non-permissive cell where virus can’t replicate

Viral gene products transform cells
-incorporation into host nucleus – disrupt growth regulation
-oncogenic transformation – promote unregulated growth (15% of cancers related to viral oncogenes)

22
Q

Host Defenses

A

-Innate immune responses
-detection of viral nucleic acids
1)TLRs
2)RLRs
-cytokine release
-IFN response
-Immune cell activation (macrophages, dendritic & NK cells)

-Adaptive immune responses
-Antibody-mediated immunity
especially for cytolytic viruses & any viremia
-T cell-mediated immunity

23
Q

Interferon Response

A

-Critical for defense against viruses
-TLRs detect both ssRNA and dsRNA in endosomes
-RLRs detect RNA in the cytoplasm

24
Q

Host Defenses

A

Two pathways induced by IFN interfere with viral RNA being translated into protein

25
Q

Most common viral diseases are

A

-common cold
-influenza
-flulike syndromes
-gastroenteritis

26
Q

Determinants of viral diseases are

A

-exposure/entry
-viral dose
-target tissue/tissue tropism
-permissiveness of cells
-host status (age, immunity, health)
-viral structure (naked vs. envelope)

27
Q

slide 21 lists out the remaining viral diseases

A
28
Q

Immune evasion does what?

A

inhibit IFN response

modification of viral antigens

cell-cell spreading (syncytia)

suppress antigen presentation

inhibition of lymphocytes

29
Q

T/F: The immune system is a major contributor to disease or symptoms caused by some viral infection

A

dis bish true

30
Q

Flu-like systemic symptoms are called what?

A

prondrome

31
Q

Type IV hypersensitivity reactions are what?

A

reaction mediated by effector T cells

32
Q

Type III hypersensitivity reactions are what?

A

IgG antibody-antigen deposits forming in small vessels and alveoli

33
Q

Hepatitis B virus

A

Hepatitis B

Immune-mediated mechanisms
-CD8+ T cells
-Antibody

34
Q

Flavivirus (dengue)

A

Hemorrhagic fever

Immune-mediated mechanisms
-Immune Complexes
-T cells

35
Q

Paramyxovirus (RSV)

A

Bronchiolitis

Immune-mediated mechanisms
-CD8+ T cells
-Antibody

36
Q

Arenavirus

A

Choriomeningitis

Immune-mediated mechanisms
-CD8+ T cells

Infectious diseases midterm (5 decks)

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