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38 Cards in this Set
- Front
- Back
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General Information Regarding Influenza and the Influenza Virus:
Influenza is a contagious ... agent caused by the influenza virus Influenza varies in severity, potentially fatal due to complications associated with the ... (i.e. pneumonia and bronchitis) Produces “Flu-like symptoms” |
respiratory
flu |
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Types of influenza virus:
three types: A, B and C -types ... and ... account for seasonal epidemics; type ... infections tend to be mild type A viruses divided into subtypes based on the hemagglutinin (H) and neuramidase (N) proteins -# hemagglutinin subtypes and # neuramidase subtypes -subtypes can be broken down into different strains type ... viruses are not divided into subtypes |
A and B
C 16 9 B |
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Influenza vaccine:
each annual influenza vaccine contains strains of influenza (the current subtypes) A (...), A (...) and influenza B |
H1N1
H3N2 |
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The influenza virion:
virion consists of a ... within a lipid envelope -the nucleocapsid consists of a ...-stranded, ... RNA genome and associated RNA-dependent polymerases *the genome exists in 8 segments (each segment encoding for either a structural or non-structural protein) the envelope has two prominent glycoproteins called ... (which is necessary for binding) and ... highly ... (different shapes) |
nucleocapsid
single negative hemagglutinin (H) neuramidase (N) pleomorphic |
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Influenza Virus Replication:
establishes an ... infection |
acute
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Influenza Virus Replication:
1. And 2. Recognition and Attachment -the viral glycoprotein ... recognizes and attaches to ... residues found on receptors on the host cells 3. Penetration -receptor-mediated ... 4. Uncoating -decrease in pH of the endosome leads to changes in the virus’s coats allowing for fusion of the viral ... to the endosome -fusion always for the ... of the viral genome |
hemagglutinin
sialic acid endocytosis envelope release |
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Influenza Virus Replication (cont.):
5. Macromolecular synthesis -the influenza genome is replicated and transcribed in the ... while translation of viral proteins occurs in the ... -(...) strand RNA must be converted to (...) strand RNA by the RNA polymerase supplied by the influenza virus *(...) strand (or mRNA) provides for multiple copies of the (...) RNA genome to be produced and the for the translation of viral mRNA into proteins -during the production of the mRNAs, viral proteins cleave the 5’ cap off of the ... mRNA and transfer the cap to the ... mRNA *shifts protein synthesis from the cellular mRNA to the viral mRNA- NO ... protein synthesis *cell is taken over by the influenza virus, high numbers of viral proteins and particles overcrowd the cell, leading to its ... 6. Assembly of virus -occurs at the cell ... at regions of highly concentrated HA and NA proteins 7. Budding of enveloped viruses -assembly and budding is associated with the plasma membrane -as the influenza virions pick up cellular receptors that contain ... molecules on the cell surface *... works to cleave off the sialic acid molecules |
nucleus
cytoplasm - + + - cellular viral cellular death membrane sialic acid neuramidase |
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Influenza Viral Spread:
Likes warm, dark places Typically contained within the ... respiratory tract (likes being in ...) establishes an acute infection spread person-to-person by virus-contaminated ... secretions |
lower
lungs respiratory |
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Routes of infection (influenza):
... (primary way) droplets, containing the virus, are expelled into the environment by coughing or sneezing and inhaled by another individual -coughing and sneezing are the natural consequence of epithelial cell death *viral infection *immune response infects epithelial cells of the upper and lower respiratory tracts -presence of ... on all epithelial cells ... (secondary way) the influenza virus can survive for several days on non-porous surfaces -contact with the mucosa can lead to infection |
Inhalation
sialic acids Fomites |
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Evasion of Host Defenses by the Influenza Virus
Overriding the effects of interferon Normal action of inteferons -interferons are produced by ... infected cells in response to the presence of dsRNA *IFN-α and IFN-β have three major functions: 1. Resistance to viral ... 2. Increase in ... expression (warns neighboring cells) 3. Activate ... cells -interferons warn neighboring cells of the viral infection *this warning increases the production of a protein kinase called ... in neighboring cells -when the virus spreads and infects neighboring cells, the PKR senses the dsRNA and subsequently phosphorylates and inactivates ... which is required for protein synthesis *loss of protein synthesis leads to the death of the virally infect cell The counteraction -the viral genome encodes an early gene product called ... -... binds dsRNA, effectively competing with the PKR produced by the cell (overcomes interferon) -the influenza virus needs only enough time to complete its viral replication cycle |
virally
replication MHC class I NK PKR eIF2 NS1 NS1 |
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Evasion of Host Defenses by the Influenza Virus
Antigenic ... process by which point mutations in influenza virus genes cause differences in the structure of the viral surface antigen -result of the low fidelity of the RNA polymerase -allows for new neutralizing antibodies accounts for the year to year antigenic differences in strains of influenza virus -may have a slight change in disease severity and some deaths |
drift
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Antigenic ...
process by which the influenza viruses reassort or exchange their segmented genomes and change their surface antigens radically -development of new types of influenza viruses results in new viruses that lead to influenza pandemics -infection of a high proportion of population -more severe disease and greater number of deaths |
Shift
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Reservoirs of influenza virus
type ... infects humans and many others animal species (zoonose) -including horses, pigs and birds type ... and ... predominantly infect humans |
A
B and C |
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How new pandemics strains arise-one theory:
recombinant viruses arise in pigs that have been co-infected with avian and human strains of influenza the genomes of both viruses are ... and result in new strains the new strains are potentially transmitted back to human (and birds) -humans with no protective immunity against the new strain will be aggressively infected |
reassorted
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Antigenic shift:
Only occurs in type ... ... event unlike antigenic drift Tend to result in influenza pandemics |
A
Infrequent |
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Viral pathogenesis of influenza virus:
inhalation of the virus is followed by the establishment of ... in the upper and lower respiratory infections -induction of ... production *... is responsible for the fever, muscle aches, headaches and fatigue -infection targets and damages mucus-secreting, ciliated and other epithelial cells destroying the ... barriers *damage mobilizes the ... immune response *cellular damage accounts for the sore throat, cough and hoarseness the destruction of the epithelial and mucosal level an individual susceptible to complications -infection with superinfecting bacteria leads to influenza-associated ... -inflammation in lower respiratory tract decreases oxygen exchange, narrows airways and lower pulmonary function exacerbating pre-exiting diseases such as asthma and ... |
infection
interferon interferon physical adaptive pneumonia cystic fibrosis |
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Rhinovirus:
Capsid -Environmentally ... Genome is a ...-stranded (...) RNA molecule There are over 100 different ... |
stable
single + serotypes |
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The common cold, the primary illness of the rhinovirus:
infection established primarily in the ... respiratory tract, but also shown to replicate in the ... respiratory tract establishes an acute infection |
upper
lower |
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Symptoms of rhinovirus infection:
the ..., accounts for 50% of cases -predominant symptoms include sneezing, nasal obstruction, nasal discharge and sore throat -other symptoms include headache cough and malaise (fever is low-grade or...) 1/3 of individuals infected with rhinovirus will be ... complications include precipitant of asthma and exacerbation of chronic bronchitis and cystic fibrosis |
common cold
absent asymptomatic |
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Viral replication of rhinovirus:
Features: -occurs in the ... -Cap-... translation of viral mRNA -Shuts down cellular cap-dependent translation -Cytolytic |
cytoplasm
independent |
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Viral replication of rhinovirus:
1. Recognition 2. Attachment majority of rhinovirus serotypes bind to ... -expressed on epithelial cells 3. Penetration 4. Uncoating 5. Macromolecular synthesis the influenza genome is replicated and transcribed in the ..., translation of viral proteins occurs in the ... Translation -internal ribosome entry site (IRES) directs translation of mRNA by internal ribosome binding -rhinovirus encodes a protein that disrupts cap-dependent initiation, shutting down translation of capped, cellular mRNAs Genome replication -upon entry of the single-stranded (...) RNA in the cytoplasm it is translated *proteins necessary for genome replication and production of new viral particles -first step copy (...) strand to form (...) strand intermediate, followed by the production of many (...) strand genomes -replication occurs on small membranous vesicles that are induced by viral proteins 6. Assembly of virus -occurs in the ... -occurs when large pool of capsid proteins is amassed 7. Release of virus -are released ... from cell |
ICAM-1
nucleus cytoplasm + + - + cytoplasm lytically |
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Viral Spread of Rhinovirus:
Spread from one host to another by virus contaminated ... secretions Establishes an acute infection Contained within the ... respiratory tract Higher infectivity in tissues that maintain a temperature around 91°F -Nares and upper respiratory tract ... prefers normal physiological temperatures -Lower respiratory tract |
respiratory
upper Influenza |
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Viral Spread of Rhinovirus:
Spread of infection mediated by ...: ensures efficient transmission to a new host spreads infection to the Eustachian tubes and the sinuses -otitis media and sinusitis Special note: rhinovirus has been isolated from the lower respiratory tract |
sneezing
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Evasion of Host Defenses by the Rhinovirus:
Decreased ... of interferon (in direct contrast with influenza): -interferes with the ... of interferon by disrupting its transport out of virally-infected cells Rapid clearance by the ... immune response “attack and surrender” (in direct contrast with influenza) -immune defense against rhinovirus is primarily mediated by the ... immune response *neutralizing antibodies are not made in sufficient quantities to protect against subsequent attacks Antigenic ... (new epitope situations) -error-prone RNA polymerase -generation of hundreds of different strains *the different strains are not efficiently keep in check by neutralizing antibodies |
production
production innate innate drift |
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Viral pathogenesis of Rhinovirus:
Infection most efficiently established in the ... respiratory tract Associated symptoms are due mainly to upper respiratory tract inflammation caused by the strong ... immunity response |
upper
innate |
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Viral Pathogenesis of Rhinovirus:
Cause of symptoms: Sneeze -triggered by the inflammation resulting from the ... response Runny nose -inflammatory mediators cause increased permeability of the capillaries that line the tissues of the upper respiratory tract Congestion -fluid accumulation due to the increased capillary permeability *some of the fluid is trapped and causes tissues to swell, constricting the airways |
innate
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Impact of cytokines:
Lower ... production: -milder “flu-like symptoms ... -released by macrophage responding to the rhinovirus *triggers a low grade fever *controls the spread of the infection by effectively ... the body temperature |
interferon
IL-1 increasing |
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Measles (Rubeola) and the Measles Virus:
Enveloped Genome is a ...-stranded (...) RNA molecule Only ... serotype exists Structurally similar to ... virus |
single
- one influenza |
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Measles (Rubeola) :
febrile illness incubation period of 7-10 days -prodrome characterized by high fever, cough, coryza (runny nose), conjunctivitis (red eye) and photophobia -individual is most ... during this period appearance of ... (major signal for measles) after disease symptoms begin -within 24 hours there is the appearance of an extensive maculopapular rash that will cover the entire body serious complications include pneumonia, encephalitis and corneal scarring |
contagious
Koplik’s spots |
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Viral Replication of Measles Virus:
-similar replication process as the ... virus, with one exception -entry strategies similar to that of the ... -Macromolecular synthesis occurs in ... -Cytolytic |
influenza
rhinovirus cytoplasm |
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Viral replication of measles virus:
1. Recognition 2. Attachment -recognition and binding to the cell receptor, the glycoprotein ..., is mediated by the hemagglutinin protein 3. Penetration -after binding to the cellular receptor, the envelope fuses with the cell membrane releasing the (...) RNA into the cytoplasm -fuses to cell membrane through the ... protein 4. Uncoating 5. Macromolecular synthesis -genome replication and translation of viral proteins occurs in the ... -(...) RNA converted to (...) RNA by the RNA-dependent RNA polymerase for replication of the genome * the RNA polymerase is able to replicate many full length (...) RNA genome from the (...) mRNA -the RNA polymerase is also capable of transcribing (+) mRNAs from the (-) RNA strands 6. Assembly of virus 7. Budding of enveloped viruses -assembly and budding is associated with the plasma membrane 8.Release of virus |
CD150
- fusion cytoplasm - + - + |
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Viral Spread of Measles:
-transmitted person to person by ... secretions |
respiratory
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Mechanism of viral spread (measles):
infection contracted by inhalation of respiratory secretions from an infected individual initial infection established in the epithelial cells of the respiratory tract -controlled by the ... immune response ... cells carry the virus to the lymph nodes where it gains access to the lymphatics establishing a systemic infection and ... the wide spread dissemination of the virus leads to infection of the conjunctive, respiratory tract, urinary tract, small blood vessels, lymphatic system and the central nervous system appearance of characteristic maculopapular rash as the result of T cells releasing ... ... typically follows rash |
innate
dendritic viremia cytokines recovery |
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Viral pathogenesis of measles virus:
establishment of a ... infection immune response causes ... -inflamed mucosal surfaces-conjunctivitis -demyelination-encephalomyelitis immunosuppression leaving an infected individual susceptible to secondary infection -Pneumonia |
systemic
inflammation |
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Evasion of Host Defenses by the Measles Virus:
One serotype of measles virus exists: -mutations are introduced into the viral genome by the RNA polymerase -mutated viral coat proteins lead to the loss of viral function (non-infectious) and are no longer recognized by ... antibodies -resulted in the existence of one serotype of measles virus |
neutralizing
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Evasion of Host Defenses by the Measles Virus:
Spread of measles virus from cell to cell through ... formation: -the fusion protein on the measles virus facilitates the fusion of the infected cell with uninfected cells leading to the formation of ... (giant, multinucleated cell) -measles virus avoids being detected by the neutralizing antibodies -CTLs are primarily responsible for destroying the ... |
syncytia
syncytia syncytia |
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Evasion of Host Defenses by the Measles Virus:
... of interferon production: -mechanism unknown |
Repression
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Evasion of Host Defenses by the Measles Virus:
... immune response: stems from the infection and destruction of dendritic cells and macrophage -dendritic cells and macrophages are directly involved in the activation of the ... immune response infected ... cells may trigger T cells to undergo apoptosis |
Suppresses
adaptive dendritic |
