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HLSC 124 - Microbiology for Health Professionals > Chapter 13 - Viruses, Viroids, and Prions > Flashcards

Chapter 13 - Viruses, Viroids, and Prions Flashcards

1
Q

Obligatory Intracellular Parasites

A

-require living host cells to multiply

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2
Q

Viruses

A

-contain a single type of nuclei acid, DNA, or RNA
-contain a protein coat
-multiply inside living cells by using synthesizing machinery of the cell
-synthesize special structures that transfer viral nucleic acid to other cells

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3
Q

Viruses Have no Enzymes

A

-no enzymes for their own metabolism, protein synthesis, ATP generation
-take over metabolic machinery of host cell

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4
Q

Host Range

A

-spectrum of host cells the virus can infect

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5
Q

Virion

A

-a complete, fully developed, infectious viral particle
-composed of nucleic acid and surrounded by a protein coat outside a host cell

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6
Q

Virus DNA

A

-have DNA or RNA but never both

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7
Q

Capsid

A

-protects the nucleic acid of a virus
-a protein coat
-allows lab ID
-allows transmission between hosts
-used for attachment

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8
Q

Capsomeres

A

-composition of capsid (subunit)
-protein subunits
-arrangement is particular to the virus

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9
Q

Envelope

A

-covers some capsids in a virus
-combination of lipids, proteins, carbohydrates
-a phospholipid bilayer
-extra layer of protection
-aids in ID

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10
Q

Spikes

A

-may cover envelopes
-carbohydrate-protein complexes
-how some viruses attach to host cells
-can be used as a means of ID (vaccine target)

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11
Q

Hemagglutination Spike

A

-resulting clumping of red blood cells by spikes
-viruses bind to RBCs and form bridges between them
-sharp

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12
Q

Neuraminidase Spike

A

-separation from host cell after infection
-rounded bulb shape

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13
Q

Non-enveloped Viruses

A

-viruses whose capsids aren’t covered by an envelope
-capsid protects nucleic acid from enzymes
-capsid promotes virus attachment to host

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14
Q

Complex Viruses

A

-bacterial viruses that have complicated structures

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15
Q

How are viruses grouped?

A

-according to how their mRNA is produced

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16
Q

Viral Species

A

-a group of viruses sharing the same genetic information and ecological niche

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17
Q

Parasite

A

-a virus
-usually asymptomatic
-use host as mixing vessel (bird, bats) to transfer genes to humans

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18
Q

Influenza

A

-can transmit from different species to others (humans)

19
Q

H1N1

A

-influenza strain
-mutates, protein spikes change
-annual flu

20
Q

Cell Cultures

A

-preferred type of growth medium for many viruses
-cells grown in culture media in the lab

21
Q

Cytopathic Effect (CPE)

A

-viruses infecting a monolayer of normal cells that cause the monolayer to deteriorate as they multiply

22
Q

One-Step Growth Curve

A

-demonstrates the multiplication of viruses
-data obtained by infecting every cell in a culture then testing for virions and viral proteins

23
Q

Lytic Cycle

A

-mechanism of multiplication
-ends with lysis and death of the host cell

24
Q

Lysogenic Cycle

A

-mechanism of multiplication
-host cell remains alive

25
Q

Retroviruses

A

-goes against the central dogma of geneties
-Reverse Transcriptase uses the viral RNA as a template to produce double stranded DNA

26
Q

Reverse Transcriptase Enzyme

A

-enzyme used in Retrovirus
-also degrades original viral RNA
-makes ss DNA from ss RNA
-the part that makes HIV dangerous

27
Q

Provirus

A

-integrated viral DNA in the host cell chromosome
-never leaves the chromosome
-protects HIV from the host’s immune system and antiviral drugs

28
Q

Human Immunodeficiency Virus (HIV)

A

-attacks T-cells
-virion has RNA genome (2 identical ss RNA)
-a backup strand
-has capsid, envelope, and spikes

29
Q

Retrovirus Multiplication and Inheritance

A
  1. virus enters via fusion between spikes and host receptors (has 2 identical ss RNA)
  2. uncoating releases two viral RNA strandsand viral enzymes reverse transcriptase
  3. reverse transcriptase copies viral RNA to prouduce ds DNA
  4. new viral DNA transported to host cell nucleus, integrated into chromosome as a provirus (viral integrase) and may be replicated
  5. transcription of provirus may occur, producing RNA for new retrovirus
  6. viral proteins processed (viral protease), some viral proteins moved to host plasma memb.
  7. mature retrovirus leaves host cell and acquires envelope and attachment spikes as it buds out
30
Q

Receptor Mediated Endocytosis

A

-how HIV gets into host cell
-HIV attaches to CD4 receptors found on host cell and releases its genome into the cell

31
Q

Provirus Stage

A

-makes new baby virions to keep the infection cycle going
-may become latent and emerge later
-can convert infected cell into a cancer cell (end stage of HIV - Kaposi’s Sarcoma)

32
Q

HIV Progression

A

-usually ~10 YEARS
-3 stages

33
Q

Syndrome

A

-a collection of symptoms

34
Q

HIV Stage A

A

-1/3 of TH cells diminished
-about 500/µm or mm³

35
Q

Lymphadenopathy

A

-viral load determines the speed of the pathogen

36
Q

Normal TH Cell COunt

A

-1500-3000

37
Q

HIV Transmission

A

-blood: 1000-10 000 infectous particles/µL
-semen: 10-1000 IP/mL
-saliva: 1 IP/mL

38
Q

HIV Treatment

A

-highly active retroviral therapy (HART)
-a cocktail of several antiviral drugs used to reduce viral replication (Zidovudine and Lamivudine)

39
Q

Why no HIV mRNA vaccine?

A

-small mutations within the person make the vaccine not possible

40
Q

Lytic Infection

A

-cells don’t make themselves permanent residents
-kill host cell
-ie. cold, influenza

41
Q

Persistent Infection

A

-don’t kill host cell
-ie. measles (SSPE/brain degeneration and death?)

42
Q

Latent Infection

A

-hide and become latent in cells
-emerge and produce new virions
-ie. Herpes (cole sores, genital warts, shingles)

43
Q

Cancer

A

-turns normal host cells into cancer cells
-ie. EB virus (herpes 4), Burkitt’s lymphoma, nasopharyngeal cancer

HLSC 124 - Microbiology for Health Professionals (18 decks)

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