Flashcards in Final Deck (64)
Loading flashcards...
1
Define a virus and give some general characteristics
-obligate intracellular parasites
-have a nucleic acid EITHER: RNA or DNA
-invaded in a protein capsid that surrounds the Na
-May contain am envelope around the capsid
2
Old taxonomic system
Based only on human symptoms
Some cause more than one disease
Didn't work for viruses that don't infect humans
3
New taxonomic system
Nucleic acid
How they replicate
Morphology
4
Major steps for lytic bacteriophage infection
- attachment
- penetration- injects just DNA or RNA (protein stays outside)
- biosynthesis
- Maturation: components assemble into virions
- release host cell dies!!
5
What is biosynthesis
Phase DNA directs synthesis of viral components using host stuff
6
Lysogenic pathway in bacteriophage
Steps are same as lytic except what happens with the DNA
- DNA sometime integrates with bacterial DNA
-bacteria can then replicate normally
- cell doesn't die
-sometimes virus DNA separates from bacterial DNA and continues with tthe lytic cycle (than cell dies)
7
What is a prophage
Happens In the lysogenic pathway
- bacterial viruses when some virus DNA integrates into the bacterial DNA
8
Animal virus life cycles
1. Lyric
2. Latent- cannot code for proteins
3. Persistent/slow-small amts of virus always found
9
Where do DNA and RNA replicate in animal viruses
DNA - in nucleus of host
RNA - in cytoplasm of host
10
How do animal viruses differ from bacteriophage replication
Attachment- •receptor on cell membrane
•av do not have tails
Penetration- •endocytosis
•fusion
11
Fusion
Envelope fuses with plasma membrane and releases capsid
12
Endocytosis
Plasma mem folds inward to form vesicle which virus is in loses the envelope
13
How do animal viruses release
Budding- enveloped
Lysis- non enveloped
14
Antivirus drugs that inter fear with DNA and RNA synthesis
1. Acyclovir
2. Ribavirin
3. Zidovudine (Azt)
15
Acyclovir
Inter fears with DNA and RNA synthesis
-for herpes virus
-administered orally/topically/or injected
16
Ribavirin
Stops RNA synthesis
- rotavirus treatment
- administered as aerosol
17
Zidovudine (Azt)
Inter fears with DNA and RNA synthesis
- HIV treatment
- blocks synthesis by reverse transcription
- fairly toxic
18
Enzyme inhibitors
1. Nevirapine
2. Indinavir and saquinavir
19
Nevirapine
Enzyme inhibitor
1. HIV treatment
2. Inactivates reverse transcriptase
20
Indinavir and saquinavir
Enzyme inhibitor
1. HIV treatment
2. Protease inhibitor
21
Interferon
A natural product of the immune system which cells can produce antiviral proteins
- hepatitis treatment
22
Prions
proteinaceous infectious particle
-causes rare degenerative disorders
• diseases with long incubation periods
• always progressive and fatal
23
Mode of prion in the body
Folds abnormally from normal cellular form
Causes large vacuoles in the brain (spongiform encephalopathy)
24
Transmission of prions
1. Eating cns from infected animal
2. Transplanting nerve tissue
3. Contaminated surgical instruments
25
Pathogenicity
How a microbe causes disease
26
What are the three main portals of entry for microbes
1. Mucus membranes
2. Skin
3. Parenteral route
27
Mucus membrane tract
1. Respiratory
2. Gi tract
3. Genitourinary tract
28
Genitourinary tract
STDs such as HIV, herpes, warts
29
Respiratory infection route
1. Most frequent of membrane areas
2. Easier entry point
•inhale dust
• drops of moisture
30
Gi tract infection tract
1. Microbes are acid and bile resistant
2. Enter in contaminated food or water or fingers
Ex. Dysentery, hep a, cholera
31
Skin rout of infection
1. Largest surface area of body
2. Virtually impenetrable if unbroken
3. Access through hair follicles and sweat glands
Ex. Ring worms, athlete foot
32
Parenteral rout of infection
1. Directly deposed beneath skin
•punctures
• bites
• abrasions
Ex. Gangrene, dengue fever, staph
33
What does LD50 and ID50 stand for? What is the difference between the two?
LD 50- leathal dose for 50% of host
IL 50- infectious dose for 50% of host
34
Why is adherence an important mechanism of pathogenicity? What molecules do microbes use for adherence?
They help a microbe resist or not stimulate host defenses
1. Glycoproteins
2. Lipoproteins
35
What are the four main ways that bacteria resist or not stimulate host defenses?
1. Capsules
2. Enzymes
3. Mycolic acid
4.structural proteins
36
What is the functions of capsules
1. Impairs phagocytosis
2. Prevents desiccation- tolerate any environment
3. Adherence
37
What is the function of the M protein?
Helps bac that live in the gi tract
1. Cell surface and fimbrae
2. Acid and heat resistant
3. Adherence
4. Prevents phagocytosis
Produced by strep pyrogens
38
What is mycolic acid and what is its function
1. Waxy lipid found in cell wall
2. Resistant to phagocytosic digestion
39
What is an exoenzyme?
Secreted from metabolism of bacteria to outside of the cell
40
What is a Leukocidin? What is a producer
Exoenzyme
1. Destroy white blood cells
2. Produce by gm+ cocci
41
Hemolysis and producer
Exoenzyme
1.. Lyse red blood cells and some Lyse white blood
2. Produced by gm+ cocci and clostridium perfrigenes
42
Coagulase and producer
Exoenzyme
1. Clots blood
2. Prevents access to bacteria from WBC by forming a barrier
3. Produced by staph sp.
43
Kinase and producer?
Exoenzyme
1. Dissolves clots that body forms to isolate infection
2. Keeps body from trapping bac
3. Produced by gm+ cocci
44
Hyaluronidase and Collagenas and producer
Exoenzymes
1. Breaks down connective tissue which helps bac spread
2, blackens tissue
3. Produced by clostridium perfrigens (c) and streptococci (h)
45
What are invasions
Proteins which rearrange cytoskeleton to enter cell
Produce actin baskets to cause mem ruffling
46
What were the main substances we talked about which cause host damage?
1. Direct damage by killing cells
2. Toxins
47
What are the major differences between exotoxins and endotoxins?
Exotoxins: are produced by living cells are are disease specific
Endotoxins: toxin released when bac dies
48
6 exotoxins
1. Diphtheria toxin
2. Erythrogenic toxin
3. Botulism toxin
4. Tetanus toxin
5. Vibrio toxin
6. Staphylococcus enterotoxins
49
Diphtheria toxin
Cytotoxic exotoxin
1. Inhibits protein synthesis
Ex. Corynebacterium diphteriae
50
Erythrogenic toxin
Cytotoxin Exotoxin
1. Damage blood capillaries which causes skin rash
Ex. Strep. Pyrogens or scarlet fever
51
Botulism toxin
Neurotoxin exotoxin
1. Prevents transmission of impulses from nerve to muscle (flaccid paralysis)
Ex. Clostridium botulinum (food poisoning)
52
Tetanus toxin
Neurotoxin exotoxin
1. Blocks the relaxation pathway of muscle contraction
Ex. Clostridium tetani (lock jaw)
53
Vibrio enterotoxin
enterotoxin exotoxin
1. Causes the discharge of fluids and electrolytes in the small intestine
Ex. Vibrio cholerae (severe diarrhea)
54
Staphylococcus enterotoxin
enterotoxin exotoxin
1. Similar to vibrio enterotoxin and toxic shock syndrome
Ex. Staphylococcus aureus
55
What is the major endotoxin? What portion of this molecule?
Lps in gm- as part of outer membrane
Lipid A proration is the endotoxin
Exposed to body when gm- dies
56
What are four responses of the body to endotoxins?
1. Immune response: release of cytotoxins
2. Activation of blood clotting (blocks Capps)
3. Fever (inhibit bac growth)(aspirin reduces f)
4. Septic shock
57
What is the end result of septic shock?
1. Loss of Bp so yes, death
Loss of bp I'd due to macrophages releasing tnf which increases Capp permeability which fluid then enters causing a drop of bp
58
What is a cytopathic effect
Visible effects of a viral infection to cells
1. Change in growth of host cell
2. Causes lysosomes to dump digestive enzymes into cell
3. Inclusion bodies form (viral gs in cytoplasm or n)
4. Syncytium form (multinuclear cells)
5, changes in host cell function
6. Interferons produced by infected cells
7. Antigens change cell surface
8. Activation of oncogenes
9. Loss of control inhibition
59
What is the cause of AIDS?
HIV
60
List some characteristics and some information about the structure of the virus?
HIV is a RNA virus
Retrovirus
2 identical strands of RNA
Reverse transcriptase
Envelope
61
How is the virus transmitted?
Most common are sex any way with infected person
Shared needles
HIV infected mothers giving vaginal birth to babies
HIV breast feeding
62
List some information about the virus life cycle (steps it takes to make more viruses).
1. Virus attaches to cd4 receptor- helper T cells
2. Corecepter also needed (cd 4/5)
3. Capsid enters cell by fusion
4. Uncoating of capsid
5. DNA May produce HIV bud
63
What are some prevention/treatment methods used for the disease?
Put a condom on yo dick!!
Don't do drugs
Don't be a whore
Or just don't have sex
64
