Exam 1 Flashcards
Which age groups are most susceptible to viral infection?
Elderly and toddlers (not newborns)
Why are toddlers more susceptible to viral infection than newborns?
Newborns gain passive immunity from their mothers through breast milk
Which vitamin is added to vaccines to enhance their effects?
Vitamin A
Vitamin A is known as an _______ because it enhances the effects of a vaccine.
Adjuvant
What are the 3 ways viruses can pass from a mother to a baby?
- Transplacental (in womb)
- Perinatal (during labor)
- Postnatal (after birth)
Mutations in ___ and ___ will make a person less susceptible to HIV
CCR4 and CCR5
Mutations in CCR4 make one less susceptible to HIV by __________.
Granting them large resistance to HIV infection
Mutations in CCR5 make one less susceptible to HIV by __________.
Making the disease progress much slower
Long-term usage of ________ will lead to an increased risk of infection
Glucocorticoids
What are restriction factors?
Proteins that block a particular infection
What molecule is implanted into the membranes of budded off visions to route them to endosomes for degradation?
Tetherin
What kinds of pathogens does innate immunity protect against?
All pathogens. Non-specific
(T/F) Innate immunity makes use of antibodies
False
Why does adaptive immunity take time?
It involves the production of antibodies
Phagocytes are a kind of _____ defense, and includes cells like ______, ______, and ______.
Mechanical
Macrophages, neutrophils, and monocytes
Phagocytes circulate through the _____ looking for foreign invaders
Blood
What is a PRR? What kind of molecule is it?
Pattern-recognition receptor. Recognize PAMPs. It is a receptor protein
What is a PAMP?
Pathogen-associated molecular pattern
How do PRRs inhibit viral replication?
Upon recognition of PAMPs, PRRs undergo a conformational change that induces a specific signaling pathway that inhibits viral replication
What kind of nucleic acid does TLR3 recognize?
Long dsRNA
What is a TLR?
Toll-like receptor. Division of PRRs.
What kind of nucleic acid do TLR7 and TLR8 recognize? Which regions does it look for?
ssRNA. Regions rich in AU and GU
What kind of nucleic acid does TLR9 recognize?
Unmethylated CpG motifs of DNA viruses
What kinds of nucleic acid do RIG-1 like receptors recognize?
Short dsRNA and ssRNA
TLRs 7, 8, & 9 as well as RIG-1 like receptors produce ____ and _____.
Type 1 interferons & inflammatory cytokines
What are interferons made of?
Small proteins
Interferons are small proteins secreted by _________.
Virally infected cells
Interferons respond at (early/late) stages of infection
Early
Explain how interferons work
Interferons bind to receptors on surrounding non-infected cells, activating gene expression of antiviral proteins that inhibit viral replication
Which 3 interferon-induced genes are most important? Explain each.
1) PKR. dsRNA-activated protein kinase. Phosphorylates eIF2 to shut down protein synthesis
2) OAS1b. Produces 2’-5’-oligo adenylate that binds to and activates RNaseL
3) RNaseL. Degrades viral RNAs
What are the 3 types of interferons?
Alpha, beta, and gamma
Defensins protect against (naked/enveloped/naked & enveloped) viruses
Naked & enveloped
What are defensins made of?
Small peptides
Alpha defensins block (naked/enveloped) viruses by what mechanism?
Naked viruses. Block them by aggregating virions on cell surface (blocking viral uncoating)
Beta defensins block (naked/enveloped) viruses by what mechanism?
Enveloped. Block them by binding to viral envelopes to disrupt the envelope, disrupting viral entry
What is the complement system composed of?
Over 30 different serum and membrane-bound glycoproteins
Complement proteins in blood are (active/inactive)
Inactive
How are complement proteins activated?
By 1 of 3 pathways. Activates membrane attack complex (MAC) causing osmotic lysis
Where are dendritic cells found?
Tissues in contact with the environment
What kinds of molecules are expressed on the surfaces of dendritic cells to identify foreign invaders?
MHC class I and II
Describe the process used by dendritic cells to stimulate an immune response
- Internalize the pathogen
- Digest the pathogen
- Display the foreign peptides on their surfaces using MHC class II molecules
- Foreign peptides are presented to TH cells
TH cells are only activated to recognize foreign antigens using the ____ _______.
B7 costimulator
Once TH cells are activated, they leave the _____ _____ and ________.
Lymph notes
Travel to the site of infection
What are the 3 types of antigen presenting cells?
Dendritic cells, macrophages, and B cells
Why is it said that TH cells act indirectly?
They recruit and activate other immune cells to eliminate pathogens
TC cells act (directly/indirectly) to destroy virally infected cells
Directly
Natural killer cells (NK cells) are activated by _____ and ______.
Interleukins and interferons
Once activated, what 3 molecules do NK cells release to kill virally infected cells?
Perforins, granzymes, and chemokines
What do perforins do?
Create pores in membranes
For a new infection, the (innate, adaptive) immune system plays an important role in the early stages of infection.
Innate
____ contains white blood cells that circulate through the lymphatic system.
Lymph
The main types of lymphocytes are __ lymphocytes and __ lymphocytes.
B lymphocytes and T lymphocytes
What are the 2 main subtypes of T lymphocytes?
TH and TC cells
Mature B cells display about _____ membrane bound antibodies
150,000
Viral antigens can act as _______.
Immunogens
What is an immunogen?
Provokes immunity when introduced into the body
(T/F) B cells patrol the lymphatic system
True
Describe the process when a B cell encounters a virus
The B cell is activated and differentiates into a large population of clones of plasma cells and a population of memory cells that express the correct antibody
Activated B cells differentiate into ______ cells and _______ B cells for 4-5 days
Plasma cells and memory B cells
What is the role of a plasma cell?
Specialize in rapidly secreting large numbers of antibodies
What is the average lifespan of a plasma cell?
1-2 weeks
What is the average lifespan of a memory B cell?
A lifetime
(T/F) Memory B cells take time to respond to future secondary infections
False.
What is an epitope?
A certain sequence of amino acids that gives an immunological response. Site on the surface of an antigen
Which antibody is most abundant (IgG, IgA, IgM)?
IgG
Which antibody crosses the placenta (IgG, IgA, IgM)?
IgG
Which antibody is a monomer (IgG, IgA, IgM)?
IgG
Which antibody is a dimer (IgG, IgA, IgM)?
IgA
Which antibody is a pentamer (IgG, IgA, IgM)?
IgM
Which antibody is most present in serum (IgG, IgA, IgM)?
IgG
Which antibody is present in body secretions and breast milk (IgG, IgA, IgM)?
IgA
Which antibody is the first responder after immunization (IgG, IgA, IgM)?
IgM
Which antibody provides years of protection (IgG, IgA, IgM)?
IgG
Which antibody lasts just a few weeks or months (IgG, IgA, IgM)?
IgM
In a primary antibody response, (IgM/IgG) antibodies are released in abundance whereas (IgM/IgG) antibodies take longer to produce
IgM, IgG
In a primary antibody response, (IgM/IgG) antibodies are released in abundance whereas (IgM/IgG) antibodies are produced in lesser abundance.
IgG, IgM
Where are T cells produced? Where do they migrate to mature?
Bone marrow. Migrate to the thymus
(T/F) T cells recognize antigens directly.
False. T cells recognize presented antigens via MHC molecules present on the outside of antigen presenting cells.
TH cells express (CD4/CD8) on their surface. They recognize antigens bound to (MHC I/MHC II)
CD4
MHC II
TC cells express (CD4/CD8) on their surface. They recognize antigens bound to (MHC I/MHC II)
CD8
MHC I
What are the viral evasion strategies (there are 7)?
- Mutate rapidly
- Hide
- Molecular mimicry
- Synthesize excessive amounts of soluble viral antigens
- Inactivate cytokine signals
- Inactivate immune cells
- Block apoptosis, complement, and interferon pathways
What is passive immunization?
Transfer of active premade antibodies.
How long does passive immunization last?
2-3 weeks, helps immunized person overcome infection
What is the rationale for vaccines?
Prevent infections (prophylactic)
What is the difference between a live and attenuated virus?
Live: Attenuated, avirulent. Live virus that is unable to produce a disease. Produces a good infection of the body, but will not produce a disease
Inactivated: Killed. Noninfectious virus particles
What factors led to the successful elimination of smallpox?
Severe disease with high mortality, no animal reservoir, no recurrence, only 1 serotype, effective diagnosis, available vaccine, non-infectious until rash appears
What is variolation?
Inoculating an individual through deliberate exposure to generate a mild disease and immunity against further severe infection
Which nations were the first to use variolation?
China and Turkey
Who was Edward Jenner?
First to approach inoculation in a scientific manner. Inoculated small child with cowpox and later smallpox. Prevented development of disease.
What are the different types of vaccines?
Live attenuated, inactivated, virion subunit, live recombinant, virus-like particles, and DNA
What is the family that poliovirus is a part of?
Picornaviridae
How large is poliovirus?
Small. 30nm
What kind of nucleic acid is poliovirus made of?
RNA. +RNA
Poliovirus is a (naked/enveloped) virus
Naked
What is the most notable feature of the poliovirus capsid?
It is acid stable
How is poliovirus transmitted?
Oral-fecal
What are the primary and secondary sites of infection for poliovirus?
Primary: Gastrointestinal tract
Secondary: CNS
What is the role of CD155 with relation to poliovirus?
CD155 is a receptor of poliovirus that belongs to the immunoglobulin superfamily
What mechanism does poliovirus use to evade the immune system?
Hides
After attachment of picornavirus to the cell surface receptors, the virion undergoes major conformational changes and ___ is lost.
VP4
Why is VPg uridylated by the RNA polymerase?
To be used as a primer to produce -mRNA, which is used as a template to make +mRNA
What mechanism is used by poliovirus to take advantage of cellular machinery?
IRES
A _____ is made and then processed into individual proteins in poliovirus.
Polyprotein
Where does the entire process of poliovirus replication occur?
In the cytoplasm
What is a procapsid?
Precursor to capsid.
Picornavirus assembly and exit. A certain ______ residue is uridylated in VPg
Tyrosine
Virions are released by (budding/cell lysis) in picornavirus
Cell lysis
What are the types of vaccines for poliovirus?
Salk (inactivated)
Sabin (attenuated)
Where are mutations present in attenuated strains of picornavirus vaccinations?
The IRES sequence
Where is oral polio vaccine used and why?
Rural communities. Doesn’t require a trained professional to administer injection
Where are polio cases found currently?
Nigeria, Pakistan, and Afghanistan
How does poliovirus inhibit host cell transcription?
Some virus proteins enter the nucleus to inhibit host cell transcription
Why can influenza epidemics be difficult to manage?
Incubation period is only 1-4 days
Large number of infectious particles shed in droplets (sneezing, coughing)
Many symptomatic individuals do not stay home
Which family is influenza part of?
Orthomyxoviridae
How many types of influenza exist?
- A, B, & C
Describe the genome and capsid (naked vs. enveloped) of the influenza virus
ve ssRNA, segmented genome, enveloped
Why does death occur when infection with influenza?
Cytokine storm. Systemic inflammatory response syndrome occurs when immune system is overreacting
The antibody response against influenza is against _____ and _____.
Hemagglutinin and neuraminidase.
What is the primary site or replication with influenza?
Ciliated epithelium
_____ (N/H) outnumbers ______(N/H) 4:1 to 5:1 in influenza.
H outnumbers N
What triggers fusion between the influenza viral membrane and the host endosomal membrane?
Low pH in endosomes
H PROTEIN MEDIATES THE LOW PH DEPENDENT FUSION EVENT
A LOW PH-DEPENDENT IRREVERSIBLE CONFORMATIONAL CHANGE OF H PROTEIN IS NECESSARY
THERE’S A FUSION PEPTIDE THAT CAUSES FUSION BETWEEN THE VIRAL AND ENDOSOMAL MEMBRANE THAT IS HIDDEN WITHIN THE VIRUS
PH CHANGE INDUCES CONFORMATIONAL CHANGE THAT EXPOSES THE FUSION PEPTIDE. 2 CELLULAR PROTEINS CLIP THE PEPTIDE, ALLOWING THE MEMBRANES TO FUSE
Where does uncoating take place for influenza?
The endosome
The viral transmembrane M2 protein forms a ___ ion channel in the viral envelope for influenza.
H+. H+ ions penetrate and weaken the interaction of viral M1 matrix protein from viral genomic RNAs. Viral RNA, NP, and RNA-dependent RNA polymerase is released into cytoplasm, exported to nucleus
What is unique to influenza
Cap snatching. Uses cap as a primer to start viral mRNA synthesis
What is the function of viral protein NS1 in influenza?
Prevents the export of cellular mRNA into the cytoplasm
Influenza virus suppresses the ________ response.
Interferon
NS1 protein binds to viral dsRNA intermediates and blocks activation of ____.
PKR
Influenza is released via (lysis/budding)
Budding
