Virology Flashcards
1
Q
What are the key characteristics of HIV retroviridae?
A
- RNA genome
- reverse transcriptase (RNA to DNA)
2
Q
What is the envelope of HIV retroviridae?
A
host-derived envelope surrounds capsid
3
Q
What are the proteins of HIV retroviridae?
A
nucelocapsid (NC), capsid (CA), and matrix (MA) proteins
4
Q
What are the two types of pathogenic human retroviruses?
A
- HIV
- Human T cell lymphotrophic virus (HTLV)
5
Q
What are the symptoms of HIV during acute infection?
A
- sore throat and fever
- immune system recovers and destroys most virions
6
Q
What are the symptoms of HIV during clinical latency?
A
- skin issues (dermatitis, eczema, psoriasis)
- T cell count continues to drop
7
Q
What are the symptoms of HIV during secondary infection?
A
chronic infections common bc immunocompromised
- oral/vaginal thrush
- gastrointestinal illnesses
- cancers
8
Q
What does Gag’s function? (1 of the 4 common genes that all retroviruses have)
A
Encodes polyprotein that contains MA, CA, and NC proteins
all 4 package into HIV virion
9
Q
What does Pro’s function? (1 of the 4 common genes that all retroviruses have)
A
Encodes protease to cut Gag and Pol into separate proteins
all 4 package into HIV virion
10
Q
What does Env’s function? (1 of the 4 common genes that all retroviruses have)
A
Encodes 2 diff envelope glycoproteins
all 4 package into HIV virion
11
Q
What does Pol’s function? (1 of the 4 common genes that all retroviruses have)
A
Encodes 2 diff enzymes as polymerase
all 4 package into HIV virion
12
Q
Which HIV protein are used to attach?
A
gp120 surface protein and CD4 protein on target cells
13
Q
Which receptors do the HIV attachment protein (gp120) bind to?
A
CCR5 or CXCR4 coreceptors
14
Q
How is the nucleocapsid in HIV released and where?
A
- How: after gp41 dissociates and changes confirmation
- Where: released into the cytosol
15
Q
What happens if the virion in HIV enters via endocytosis?
A
It’s a dead end and non productive
16
Q
Where does uncoating occur and which proteins are released in HIV?
A
- Disassembles into cytosol
- Viral and cellular proteins
17
Q
What is the final outcome of reverse transcription in HIV?
A
Double stranded DNA viral genome
18
Q
Where does RT occur in HIV?
A
in cytosol while synthesizing complimentary copy of ssDNA
19
Q
How does the HIV viral genome get into the nucleus?
A
semi-intact capsids attach to MT (and actin MF and vimentin IF) to move towards nucleus
20
Q
What happens once the HIV viral genome is in the nucleus? (i.e. enzymes involved?)
A
Inserted into the host genome by cutting from LTR and chromosome to ligate strands together
21
Q
Which enzymes are used for gene expression and replication in HIV?
A
LTR, Tat, and Rev
22
Q
Are the enzymes are used for gene expression and replication viral or host enzymes?
A
All 3 are viral enzymes
23
Q
What is the role of LTR enzyme in HIV?
A
Promoter region where transcription begins
24
Q
What is the role of Tat enzyme in HIV?
A
Transcription factor that guides RNA polymerase to host genome
(more transcription of HIV)
25
What is the role of Rev enzyme in HIV?
Viral mRNA's are capped and transported out of nucleus
26
How are new virions replicated and released in HIV?
HIV replicated with CD4+ helper T cells and enhanced by Vpu protein
27
Which enzymes are involved in HIV maturation and what is their role?
- Vpu protein: Envelope on HIV is enhanced and removed CD4 helper from membrane
- Nucleocapsid coats RNA
28
How is HIV transmitted?
- Sexually
- Blood exposures (needles, IV drugs)
- Vertically (mother to child)
**must penetrate through tissue**
29
Which cell types does HIV bind to?
CD4+ Th cells and macrophages
30
How does HIV spread and where?
Moves through blood, and reach brain (dementia) and immune cells
31
What type of damage does HIV cause directly vs. damage caused by our own immune system?
HIV causes: Inactivation of monocytes/macrophages = death of helper T cells
Our body: Infected macrophages release inflammatory cytokines (dementia)
32
What strategies does HIV use to evade the host immune response?
- HIV nef: binds to plasma membrane and triggers endocytosis
- Hiding in macrophages and stem cells
- Kills Th cells and inactivated macrophages
- Mutations in RT
33
How is HIV diagnosed?
ELISA or PCR, confirmed with Western blot
34
How is HIV treated?
HAART (Highly active antiretroviral therapy)
35
What types of drugs are currently available for HIV and what do they target?
- Reverse transcripterase: blocks active site or allosteric inhibition
- Protease inhibitors: Blocks virion maturation and spread
36
How is HIV prevented?
Safe sex, don't share needles, treat mothers with anti-retrovirals, don't recap needles
37
Common features of negative sense RNA viruses
- Size: small genetically
- Structure: enveloped negative-sense RNA genome
- Replication: only in cytosol (NO DNA INVOLVED)
38
What do Rhabdoviruses look like structurally and genetically?
Structure: bullet shaped helical capsid
Genetically: single pieces of neg sense RNA
39
Two main types of Rhabdoviruses that cause human disease
VSV and Rabies
40
Location of Nucleoprotein in structure of Rhabdoviruses virions
Nucleocapsid
41
Function of Nucleoprotein in structure of Rhabdoviruses virions
Protects RNA genome
42
Location of Polymerase phosphoprotein in structure of Rhabdoviruses virions
Associated w nucleocapsid
43
Function of Polymerase phosphoprotein in structure of Rhabdoviruses virions
RNA polymerase subunit
44
Location of Matrix in structure of Rhabdoviruses virions
Between nucleocapsid and envelope
45
Function of Matrix in structure of Rhabdoviruses virions
Virion assembly
46
Location of glycoprotein in structure of Rhabdoviruses virions
Transmembrane envelope glycoprotein
47
Function of glycoprotein in structure of Rhabdoviruses virions
Viral attachment protein
48
Location of large protein in structure of Rhabdoviruses virions
Associated with nucleocapsid
49
Function of large protein in structure of Rhabdoviruses virions
RNA polymerase
50
What specific viral proteins are involved in replication of Rhabdoviridae and what do they do?
- G protein: binds to host receptors
- L/P: uses genome to make gene into full length
- G and M: newly made G and M get sent to plasma membrane
51
Characteristic symptoms of early Rabies infection
Fever, headache, twitching **tingling at site of infection**
52
Characteristic symptoms of later Rabies infection
Confusion, increased salvation (frothing), hydrophobia, eventual coma and death
53
How is Rabies acquired (and what types of animals)?
Contact with saliva from infected animal following a bite
Can get from cats and dogs, bats, raccoons, foxes, etc
54
What are the two major clinical forms of Rabies seen in dogs?
- Excitable form: animals become irritable and hyperactive (frothing), prone to attacking other animals
- Dumb form: Animals stop eating, throat closes and dies
55
How does the Rabies virus attach to our cells (receptor, viral protein, cell type(s))?
Virus attaches to unknown cell receptors on muscle tissue and connective tissue
56
After initial replication, where does the Rabies virus go in the body and how?
Virus binds to peripheral neuron axon terminus and enters cytosol
Attaches to NAR and moves from peripheral to CNS
57
After replicating in that new location, where does the Rabies virus go next and how?
Replicates well in brain and spinal cord, then spreads to all the tissue in the body and salivary glands
58
How does the Rabies virus evade destruction by Tc cells?
FasL kills invading T cells
Leads to virally infected cells surviving
59
What causes damage during Rabies infection and how does that occur?
Infected cells have cytosolic inclusions (metabolic products)
60
What are Negri bodies?
Round inclusions in the cytoplasm of nerve cells in animals infected with Rabies
61
What is special about the viral N protein in Rabies?
Can function as a superantigen (excessive activation of immune system)
62
How is Rabies diagnosed?
- Remove brain from infected and do cross section to look for Negri bodies. Inject brain tissue into mice
- Interstitial fluid of brain tagged for anti-rabies antibodies
- PCR from saliva
63
How is Rabies prevented?
Prevent bites, stay away from wild animals, vaccinate pets and wild animals
64
How is Rabies treated?
NO treatment exists once symptoms appear!
65
General structure of Influenza virion
- Segmented RNA genome
- Encapsulated by NP protein
- Nucleocapsid surrounded by matrix protein
66
What is different about Influenza genome (when compared to other Rhabdoviruses)?
Influenza is segmented (contains multiple pieces of RNA)
67
Differences between Influenza A vs B/C viruses
Flu A: major pathogen that infects, multiple mutations can occur
Flu B and C: Minor outbreaks, no animal reservoir, rare mutations
68
What are the symptoms of Influenza disease?
Fever, headache, muscle ache, dry cough
Secondary illnesses can occur (pneumonia, bronchitis, encephalitis)
69
Basic history of major flu pandemics
- First epidemic: 1500
- Spanish Flu: 1918
- Asian Flu: 1957
- Hong Kong Flu: 1968
70
How is Influenza virus transmitted?
Person to person contact, through respiratory droplets
71
How does the Influenza virus attach to our cells?
HA protein binds to sialic acid linked to galactose found in respiratory epithelial cells
72
What viral protein and host receptors are involved in Influenza?
HA must recognize sialic acid-gal linkage
73
What is different about the receptor in birds, humans, and pigs in Influenza?
Humans have A2-6 receptors
Birds and pigs have A2-3
74
How does the receptor affect NA and HA compatibility in Influenza?
NA must match HA for infectivity
75
How does the Influenza virus enter the cell?
Endocytosis occurs, allowing for acidification of the endoscope
76
In Influenza, once in a phagosome, acidification takes place. What are two affects of that acidification?
- Causes HA to do **conformational change** (Fusion of envelope with endoscope)
- M2 protein allows H+ to **trigger uncoating**
77
Where do released genomic pieces go and why does it go there (and why is that unique to Influenza)?
Genomes transported out via nuclear pore
78
What role does NS2 play in viral replication of Influenza?
Export viral mRNA to cytosol
79
What role does NA play in the release process of Influenza?
Cuts and releases into surface, also cuts of SA off of envelope
80
How do the viruses spread in Influenza?
Particals released from apical surface inject into respiratory epithelial tissue
81
What type of tissue damage is observed (and what tissue is primarily affected)?
Extensive damage to alveoli, massive edema (pneumonia), necrosis and hemorrhage
82
What is unique about H5N1 in Influenza?
It's a strain that is neurotrophic and can spread to CNS (not typical)
83
What is meant by antigenic drift vs shift in Influenza?
Drift: MUTATIONS
Shift: COMPLETELY DIFF GENE MADE
84
Why are pigs special and what is meant by a sentinel animal in Influenza?
Pigs have sialic acid found in humans and are reservoir for diff flus mixing together
85
How is Influenza diagnosed?
RT-PCR, rapid flu, and immunofluorescense
86
Structure of the measles virus
Genome = single RNA strand
Found within helical capsid
87
What are symptoms of Measles?
1-2 weeks post infection: fever, cough, conjuctivitis, rash, and Koplik spots
88
What are Koplik spots in Measles?
Raised white spots on the tongue with irregular redness (can't be scraped off)
89
How is Measles transmitted between hosts?
Inhalation of respiratory droplets, can also be acquired from eye exposure to respiratory droplets
90
How does Measles attach (viral proteins and host receptors involved?) and what occurs as a result?
- H protein attaches to receptors on epithelium
- Binds to CD46 protein and unknown receptor
- Binding triggers endocytosis
91
What role does the F protein play in the Measles process?
Causes membrane fusion
92
What are multinucleated giant cells (syncytia) and how do they arise in Measles?
Multiple cells fused together to make one big cell, HELPS VIRUS SPREAD
93
Where does Measles spread initially and what happens as a result?
Virions released spread into bloodstream, can cause primary veremia
94
Where does Measles spread during the second viremia?
GI tract, skin, CNS
95
How does Measles damage our tissue?
Mediated cell death, inflammation and cell-mediated immunity can lead to Encephalitis
96
How is Measles diagnosed?
Immunofluorescence and ELISA
97
How is Measles treated?
No actual treatment besides waiting it out (give vitamin A and treat symptoms)
98
How is Measles prevented?
Vaccine
99
How is Influenza treated?
Inhibit M2 and uncoating and inhibit neuraminidase
100
How is Influenza prevented?
Vaccine
