Viruses, Viroids and Prions Flashcards
(211 cards)
1
Q
Viruses
A
- Aren’t considered living
- Have DNA or RNA but not both
- protein coat
- has no ribosomes
2
Q
Why are viruses considered non-living
A
- They need a host to cause infection
- Once it finds a host it will begin to multiply and cause infection
3
Q
Obligatory intracellular parasite
A
Requires a host to multiply
4
Q
Host range
A
The spectrum of the virus to cause infection to a host cell
5
Q
Bacteriophage
A
Viruses that infect bacteria
6
Q
How does viruses infect the host
A
- Virus chemically interacts with specific receptors sites on the surface of the cell
- The virus and the cell are held together by weak hydrogen bonds that later get stronger
7
Q
Phage therapy
A
- Using bacteriophages to treat bacterial infections
- using viruses to treat diseases
8
Q
Virons
A
- Complete, fully developed viral infectious particles
- Composed of nucleic acids and surrounded by protein coats
9
Q
Nucleic acid structures of viruses
A
- encoded by RNA or DNA but not both
- Single stranded or double stranded
- can be linear or circular
10
Q
Capsid
A
- Protein coat made of capsomeres
- Visible in electron mircographs
- protect nucleic acids from nucleases enzymes
11
Q
Envelope
A
-Some combination of lipid, protein, or carbohydrates caoting on some viruses
12
Q
Spikes
A
- projections from outer surfaces
-Protein complexes - Can be clumps of red blood cells (hemagglutination)
13
Q
Viral morphology
A
-Helical
- Polyhedral
- Enveloped
- Complex
- Viroid
14
Q
Helical virus
A
- Hollow, cylindrical capsid
- rabies and ebola
15
Q
Polyhederal virus
A
- many sided
- animals, plants, and bacterial viruses
- poliovirus, adenvirus
16
Q
Complex virus
A
- complicated structures
- may have a polyhedral head and a helical tail or vice versa
- Poxvirus
17
Q
Viroid
A
- Composed mostly of short strands of circular, single- strand RNA with no protein coating
- smallest infectious pathogens known
18
Q
Enveloped virus
A
- roughly spherical
- influenza, human herpes
19
Q
What viral morphology causes rabies and ebola
A
Helical
20
Q
What viral morphology has a polyhedral head and a helical tail or vice vera
A
Complex virus
21
Q
What viral morphology causes poxvirus
A
complex virus
22
Q
What viral morphology is know to be the smallest infectious pathogen
A
viroid
23
Q
What viral morphology causes human herpes and influenza
A
enveloped virus
24
Q
What viral morphology causes poliovirus and adenovirus
A
polyhedral virus
25
Taxonomy of viruses
- classified into families by their genomics and structures
- genus name: -virus
- family name: -viridae
- order name: - ales
26
- virus
genus name
- herpesvirus
27
-viridae
family name
- simplexvirus
28
- ales
order name
- human herpesvirusale
29
What do you grow bacteriophages in at the lab
liquid broth
solid medium
30
What can you grow animal viruses in at the lab
- living animals
- embryonated eggs
- cell cultures
31
growing viruses in living animals
- most studies about the immune system
- some viruses cant be grown outside of the human body
- use mice, rabbits and guinea pigs
32
growing viruses in embryonated eggs
- viruses are injected into a small hole in an egg
- helps develop viruses
- viral growth is determined w/ the death of the egg
33
growing viruses in cell culture
-cell growth in cultured media
- more convenient than whole animals and eggs
- suspended in a solution that provides nutrients, growth factors and osmotic pressures
34
Cytopathic effect
visible effects on the host cell caused by the virus resulting in cell damage or death
35
Primary cell lines
- tissues slices
- tend to die after a few generations
36
Diploid cell lines
- human embryos
- maintain life for about 100 generation
- used for culturing viruses that require a human host
37
Continuous cell lines
- routinely grown in a lab
- cancer cells
- indefinite number of generations
38
Viral identification
- blotting
- electron microscope
- ploymerase chain reaction
39
For viruses to multiply they
- invade a host cells
- must take over the host metabolic machinery
40
Lytic cycle
- phage causes lysis and death of the host cell
41
Lysogenic cycle
- Phage DNA is incorporated in the host
- phage conversion
- specialized transduction
42
Lytic cycle stages
1. attachment
2. penetration
3. biosynthesis
4. maturation
5. release
43
What is the attachment stage of the lytic cycle
- phage attaches by the tail fibers to the host cell
44
What is the penetration stage of the lytic cycle
- phage lysozymes open the cell wall
- the tail sheath forces the tails core and DNA into the cell
45
What is the biosynthesis stage of the lytic cycle
- production of phage DNA and proteins
46
What is the maturation stage of the lytic cycle
- assembly of phage particles
47
What is the release stage of the lytic cycle
- phage lysozymes break the cell wall
48
What stage does the sheath tail forces DNA and core tail into a cell
Penetration
48
In what stage does lysozyme attach to the tail fibers of host cells
Attachment
48
In what stage of the lytic cycle are DNA and protein produced
Biosynthesis
49
At what stage in the lytic cycle are phages particles assembled
Maturation
50
At what stage in the lytic cycle do phage lysozyme break the cell wall
Release
51
Lysogeny
Phage remains latent
52
Prophage
- Inserted phage DNA
- Also replicated when host cells replicate their chromosomes
53
Phage conversion
the host cell exhibits new properties
54
stages of multiplication of animals viruses
- attachment
- entry
- uncoating
- biosynthesis
-maturation
- release
55
What happens in the attachment stage of multiplication of animal viruses
virus attaches to the cell membrane
56
What happens in the entry stage of multiplication of animal viruses
enter by receptor-mediated endocytosis or fusion
57
What happens in the uncoating stage of multiplication of animal viruses
- uncoating of viral or host enzymes
58
What happens in the biosynthesis stage of multiplication of animal viruses
- production of nucleic acid and proteins
59
What happens in the maturation stage of multiplication of animal viruses
nucleic acid and capsid proteins assemble
60
What happens in the release stage of multiplication of animal viruses
viruses are released by budding(enveloped viruses) or rupture
61
In what stage of the multiplication of animal viruses does the virus go through fusion or receptor-mediated endocytosis
Entry
62
In what stage of the multiplication of animal viruses does production of nucleic acids and proteins get produced
biosynthesis
63
In what stage of the multiplication of animal viruses does nucleic acids and capsid proteins assemble
maturation
64
In what stage of the multiplication of animal viruses are budding and ruptures apart of
release
65
Where do viruses replicate their DNA
in the nucleus of thee host cell using viral enzymes
66
Adenoviridae
- double stranded DNA
- non-enveloped
- Causes respiratory infections in humans
- causes tumors in animals
67
Poxviridae
- double stranded DNA
- enveloped
- causes skin lesions
- vaccinnia and smallpox viruses
68
Herpesviridae
- Double stranded DNA
- enveloped
- HHV-1 & 2 : Simplexvirus: cold sores
- HHV- 3: Varicellovirus: chickenpox
- HHV-4: Lymphocrytovirus: causes mononucleosis
- HHV-5: Cytomegalovirus
- HHV-6 & 7: Roseolovirus
- HHV-8 Rhadinovirus: causes Kaposi's sarcoma
69
Papovaviridae
- double stranded DNA
- non-enveloped
- papillomavirus
- causes warts and can transform cells and cause cancer
70
Hepadnaviridae
- double stranded
- enveloped
- hepatitis B virus
- uses reverse transcriptase to make DNA from RNA
71
What is a sarcoma
cancer of connective tissue
72
What is adenocarcinomas
cancer of glandular epithelial tissue
73
What are oncogenes
transform normal cell into cancerous cells
74
What is the oncogenic viruses
- viruses that become intergrated into the host cell DNA
- induces tumors
75
what are reasons cancer goes unnoticed
- contagious viral diseases
- cancers may not develop until long after viral infection
- viruses infect cells but not induce cells
76
Normal cells to tumor cells
- alterations of genetic material
- oncogenes
77
Oncogenes
- can bring about malignant transformation
- can be activated by abnormal functions
- mutagenic chemical
- high-energy radiation
- viruses
78
Oncogenic viruses
- oncoviruses
- viruses capable of inducing tumors in animals
79
transformation of tumor cells
- change normal cells into cancerous cells
- tend to be irregularly shaped
80
Tumor specific transplantation antigens (TSTA)
- Viral antigens on the surface of a transformed cell
81
DNA oncogenic viruses
- found in several families of of DNA containing viruses
- adenoviridae, herpesviridae, poxviridae and more
- HPV and HBV
82
RNA oncogenic viruses
- only found in the Retroviridae family
- Human T-cell leukemia viruses
- Feline leukemia virus
- produce cancer using reverse transcriptase
83
Is herpesvirides, anedoviriade RNA or DNA oncogenic
DNA
84
are viruses in the Retroviridae DNA or RNA oncogenic
RNA
85
Does RNA or DNA oncogenic viruses uses reverse transcriptase
RNA
86
What viruses are used to treat cancer
Oncolytic viruses
- tumor destorying
- selectivly infect or kill tumor cells
- cause immune response against tumor cells
- ex: herpesvirus to treat melanoma
87
Examples of latent diseases
- cold sores
- leukemia
- Shingles
88
Examples of persistent diseases
-Cervical cancer
- HIV/AIDS
- Liver cancer
89
Prions
- few infections are caused by prions
- consist of a self replicating protein with no detectable nucleic acids
90
Types of diseases prions cause
- Mad cows disease
- Creutzfeldt-Jakob disease
- Fatal familia insomnia
- Sheep scrapie
91
What causes prion infections
- normal host glycoprotein( PrPc) converts into an infectious form (PrPsc)
- Change is in the 20th chromosome
92
Microbial antagonism
The competition between mircobes
93
Symobiosis
- relationship between normal microbiota and the host
94
Commensalism
- 1 organism benefits and the other is unaffected
95
Mutualism
Both organisms benefit
96
Parasitism
1 organism benefits and the other suffers
97
can normal microbiota cause disease
Yes some are opportunistic pathogen
98
What is Koch's postulates
process of how to link a specific microbe to a specific disease
99
Step of Koch's postulates
1. same pathogen much be present in every case of the disease
2. pathogen must be isolated from the diseased host and grown in a pure culture
3. pathogen from the pure culture must cause the disease when its inoculated into a healthy animal
4. Pathogen must be isolated from the inoculated animal and be shown as the original organism
100
Exceptions to Koch's postulates
- Some pathogens cant be grown outside of a human host
- some microbes have never been cultured
- some pathogens cause many disease conditions
101
What are the classification of infections disease
- Symptoms
- Signs
- Syndromes
102
Symptoms
Change in body function that are felt by the patient b/c of disease
103
Signs
changes in the body that can be measures or observed b/c of disease
104
Syndrome
specific group of songs and symptoms that accompany a disease
105
How do you acquire normal mircobiota
through foods, your environment and other people
106
Types of occurrence of a
disease
- Sporadic
- Endemic
- Epidemic
- Pandemic
107
What is sporadic disease
Disease that only occurs occasionally
- ex: typhoid fever
108
What is an endemic disease
Disease constantly present in a population
- ex: common cold
109
What is an epidemic
disease acquired by many people in an area in a short amount of time
- ex. AIDS
110
What is an pandemic disease
worldwide disease
-ex: COVID-19, FLU, AIDS
111
Acute disease
- develops rapidly but lasts a short time
-influenza
112
Chronic disease
symptoms develop slowly
- cancer, alzheimers
113
Subacute disease
Intermediate between acute and chronic
- panecephalitis (rare brain disease)
114
Latent disease
- inactive cause no causative agent but is later activated and produces symptoms
115
Herd immunity
most of a population is immune to a disease
116
Local infections
pathogens are limited to a small portion of the host
117
Systemic infection
infection throughout the body
118
Focal infection
systemic infection that was originally a local infection
119
Sepsis
toxic inflammatory condition b/c the spread of microbes like bacteria and their toxins
120
Bacteremia
Bacteria in the blood
121
Septicemia
growth of bacteria in the blood
- blood posioning
122
Primary infection
acute infection that causes the initial infection
123
secondary infection
opportunistic infections after the primary infection
124
What makes you more susceptible to disease
gender, age, lifestyle, nutrition, inherited traits, chemotherapy ect.
125
What are the stages of development in disease
Incubation period
prodromal period
period of illness
period of decline
period of convalescence
126
Incubation period
time between initial infection and first signs and symptom
127
Prodromal period
short period after incubation
mild symptoms
128
Period of illness
disease is most severe
129
Period of decline
signs and symptoms reduce
recovery stage
130
Period of convalescence
body returns to normal
131
What are the types of reserviors for infections
- Human (carriers)
- Animals (zoonoese)
- from animal to human
- nonliving
- soil and water
132
Types of contact trasmission
Direct
Indirect
Droplet
133
Direct trasnmission
- requires close association between the infected and a susceptible host
- kissing, touching, sex ect...
134
Indirect contact transmission
to a host from a non-living object (fomite)
- door knobs, clothing, money ect.
135
Droplet tranmission
airborne droplets spread less than l meter
- sneezing, coughing, talking ect.
136
Vertical transmission
Transferred through a medium
- air, water, food, blood ect..
137
types of vertical transmission
- Airborne
- Waterborne
- Foodborne
138
Airborne vertical transmission
by dust
- coughing and sneezing
139
Waterborne vertical transmission
- untreated or poorly treated sewers
- Cholera, leptospirosis
140
Foodborne vertical transmission
- mainly through foods that aren't cook correctly and poor sanitation/ refridgeration
141
What are vectors
- Animals that carry pathogens from one host to another
- ex: insects
142
What is an emerging infectious disease
- new or changing and increasing or has potential to increase
143
how infections emerge
- genetic recombination
- evolution
- overuse of mircobials
- ecological changes
- failure of public health measures
144
Morbidity vs Mortality
Morbidity: # of people affected in a total population at a giving time
Mortality: # of deaths in the population at a given time
145
Pathogenicity
ability to cause disease
146
Virulence
the degree of pathogenicity
- the potency
147
How does mircoorganisms enter the host
Mucocus membrane
Conjuctiva of the eye
Parenteral route
148
entering the mucous membrane
most pathogens perferred entry portals
149
microorganisms entering through the parental route
broken skin
bites
Injections
150
ID50
infectious dose for 50% of populations sample
- measures virulence
151
LD50
Lethal dose for 50% of populations sample
- measures potency of toxins
152
Microorganisms entering through the skin
- unbroken skin is impenetrable
- gain access through body openings
- hair follicles, sweat glands
153
Adherence
pathogens attach to host tissue
154
Adhesins
pathogens binding to receptor on host cell
- glycocalyx
- fimbriaae
155
Components of the cell wall
- M-protein
Resist phagocytosis
- Opa
proteins allow attachment
- Waxy lipid
resist digestion
156
Coagulases
Coagulate fibrinogen
157
Kinases
digest fibrin clot
158
Hyaluronidase
- digest polysaccharides that hold cells together
- helps spread microorganisms from their initial site of infection
159
Collagenase
- break down collagen
- hydrolyzes hyaluronic acid
160
IgA proteases
-destroys IgA antibodies
-defense against adherence
161
Do moth pathogenic bacteria require iron
yes
162
Animal iron-bonding molecules
Transferrin ( serum )
Ferritin ( cytoplasm )
Lactoferrin ( sweat, tears and milk)
163
What direct damage happends to the host after siderophoers
- disrupts host cell function
- produce waste
- multiply in host cell and causes ruptures
164
Toxins
posions substance produced by microorganisms
- produce fever, cardiovascular problems, shock ect.
165
Toxigenicity
ability of a microbe to produce a toxin
166
Toxemia
toxins in the host blood
167
Intoxication
presence of toxins without microbial growth
168
exotoxins
- Secreted by bacteria and produced by proteins
169
Antitoxins
Antibodies against a specific exotoxins
170
Toxiods
inactivated exotoxins used in vaccines
171
Leukocidins
kill phagocytic leukocytes
172
Hemolysins
Kills erythrocytes by forming protein channels
173
Streptolysins
hemolysins produced by streptcocci
174
Lysogenic conversion
- changes characteristics of a microbe due to incorporation of prophage
175
Are endotoxins soluble or insoluble
- Soluble
- easily diffuse into blood and rapidly transport through the body
176
What do endotoxins destroy
-Parts of the host cells
- Inhibits certain metabolic functions
177
What does antitoxins provide immunity from
exotoxins
178
How can you inactivate exotoxins
Heat
Formakdehydes
Iodine
other chemicals
179
Neurotoxins
affect the nerve cells
180
Cardiotoxins
Affect the heart cells
181
Hepatotoxins
affects the liver cells
182
Leukotoxin
affects the leukoytes
183
Cytotoxins
affects a varitey of cells
184
Enterotoxins
attack the gastrointestinal cells
185
Types of endotoxin
- A-B toxins
- Membrane disrtupting toxin
- superantigens
186
A-B Toxin
- polypeptide
- A side (active enzyme component)
B side: binding component
187
Genotoxins
- made by some gram neg. bacteria
- chemical that damages DNA or RNA
- causes mutations, disrupts cell divison and my lead to cancer
188
Membrane disrupting toxins
- causes lysis I host cells
- by forming protein channels in the plasma membrane
189
Leukocidins
toxins that kill leukocytes
- produced by staphylococci and streptococci
190
Hemolysins
- toxins that kill red blood cells (erythrocytes)
- streptococci produce streptolysis
191
Superantigens
- provoke immune response
- Stimulates T-cells
- staphylococcal toxins, toxic shock syndrome
- caused by food posioning, encourage bacterial growthE
192
Exotoxins
- Toxin is part of the bacteria
- outer portion of the cell wall of gram-neg,
- consist of lipoproteins, phosholipids and lipoploysaccharides ( lipid A)
- stimulates macrophages to release cytokines in toxic levels
- Produces chills, aches, weakness, shock, death and can induce miscarriges
- can activate blood clotting protein
- don't promote formation of effective antitoxins
- antitoxins that are produced can enhance effects of the toxin
193
Toxic shock
- life- threatening decrease in blood pressure
- affects kidneys, lungs, and gastrointestinal tract
-weakens blood barrier that protected the nervous system
- also causes more bacteria to enter the bloodstream
194
Septic shock
- caused by bacterial toxin
- gram-neg. induce endotoxic shock
195
Cytopathic effects
- visible effects of viral infection
- stop cell synthesis
- changes host cells functions
- produces interferons to protect uninfected cells
196
lysogenic conversion
- changes in characteristics of microbes due to a phage
- results in immunity of the bacterial cell to the phage
197
Viruses can produce _______ cytopathic effects
- macromolecular synthensis in host cells which could inhibit mitosis
- Host cells lysosomes release enzymes
- make infected cells clump together to cause colds, smallpox, measles ect.
- change host cell functions
- induce antigenic changes
- induce chromosomal changes in host cell
- can cause cancer tranformations in host cells
198
Interferons
- Alpha and beta
- stimulates macrophages activity (which plays a role in disease elimination)
199
How does interferons protect their neighbors
- inhibits synthesis of viral proteins
- kill infected host cell ( apoptosis)
200
Pathogenic fungi
- no defined cell wall
- metebolic products that are toxic to humans
- capsules prevent phagocytosis
201
Trichothecenes fungi
- cause chills, nausea, headaches , vomitting if ingested
- some are resistant to antifungal drugs
202
Erogotism fungi
- contains sclerota which is highly resistant to mycelia
- causes hallucinations
203
Mycotoxins fungi
- causes death if ingested
- phalloidim and amanitin
204
Pathogenic protozoa
- invade host cell and reproduce to casue ruptures
- cause chronic disease
- grows in phagocytes
205
Helmiths
- use host tissue to grow and produce parasitic mass to damage cellular
206
Algae
- some produce neurotoxins
- shellfish
207
Portals of exit
- secretions
- excretion
- dischage
- tissue
208
Systems of exits
- respiratory
- mouth, nose during coughing or sneezing
- tuberculosis, whooping cough, flu
- Gastrointestinal
- feces, saliva
- rabies, salmellosis, cholera, STI
- Skin or wounds
- drainage from wound can spread bacteria
- AIDS, hepititas B,
-Blood
- needles, syringes, bug bites
209
