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113 Cards in this Set
- Front
- Back
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How is influenza transmitted?
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respiratory epithelium
-so, virions that get into your respiratory tract |
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How many types of colds are there?
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>200 different virures + Group A strep (bacterial)
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Why do we catch more colds in the winter than in the summer?
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Children in school
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Why is a vaccine against the common cold impossible?
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The more different antigens you put together into a single vaccine, the lower the mean geometric antibody titer response to any single component!
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Is the cold endemic or epidemnic?
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endemic
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How is influenza easily distinguishable from the common cold?
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-more serious illness
-can't get out of bed |
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How long is the influenza incubation period (to most severe symptoms)?
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3 days
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Name some symptoms of flu:
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-headache
-malaise -myalgias -nasal obstruction + discharge -throat pain -cough |
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Is influenza endemic or epidemic?
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epidemic
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When did the 1986 Dallas flu epidemic peak?
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in February
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Over the course of history, what have been the two major killers, in terms of infectious diseases?
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Influenza
Typhoid |
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What was the peak death rate of Spanish flu?
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600 deaths/100 000
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What is the term for a disease causing world-wide outbreaks?
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pandemic
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Is a pandemic necessarily severe?
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no
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How was Asian flu of 1957 spread around the U.S.?
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by girl scouts
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What was the case fatality rate of 1957 Asian flu?
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0.5%
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What was the case fatality rate of 1918 Spanish flu?
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5%
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What has been the case fatality rate of H1N1 of 2009, thus far?
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0.05-0.1%
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What does flu do to the trachea/respiratory tract?
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-infects and kills cells of respiratory tract
-Kills goblet cells -Kills ciliated cells next -leaves only basal cells -no more mucociliary defenses |
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Why do people tend to develop bacterial pneumoniae following flu?
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Since the non-specific defense have been breached, a secondary infection can easily take place.
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Which antibodies are generated against flu?
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-anti-Hemagglutinin (HA)
-anti-Neuraminidase (NA) both surface glycoproteins on the envelope of Influenza |
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In which species is Influenza A seen?
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all mammalian and avian species
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How many HA and NA families are there?
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>16 HA
11 NA |
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Which strains of influenza are in the typical seasonal vaccine?
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H3N2
H1N1 |
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If you got the flu vaccine last year, are you immune to this year's flu?
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No!!
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Which are the two most recent flu epidemics after 1918 and prior to 2009?
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1957 - Asian flu - H2N2
1967 - Hong Kong flu - H3N2 |
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What is the evolutionary advantage of the periodicity of flu viruses?
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evasion of host-immunity
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Why do flu vaccines deminish in effectivenes each year?
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antigenic drift
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In which situation would a flu vaccine for a given year have 0 effectivenes the following year?
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antigenic shift
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How does antigenic shift occur?
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genetic recombination between human strains of the virus and other mammalian/avian strains (with different HA/NA families)
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What is the typical amount of antigenic drift?
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1% amino acid change (in antigenic portion)/year
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Why did the H1N1 strain of flu reappear in 1976, after 20 years of not being observed?
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likely due to a lab mishap, since it was only 1-2% different from the 1956 variety
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What was the cause of 1976 swine flu scare?
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Fort Dix, NJ
Military recruit from a pig farm died from flu (100% swine strain) |
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Why did Gerry Ford lose the election?
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He made a vaccine for swine flu, even though it ended up being unnecessary...(1/1 000 000 get Guillaume-Berret syndrome = paralysis)
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How did the soldier manage to catch a virus that was 100% swine?
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by the inocculum effect (adult hog sneeze 500-100mL)
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Which flu is the 2009 H1N1 most closely related to antigenically?
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strain from the 1950s
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What is the approximate size of an influenza virus?
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about 100nm
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What kind of nucleocapsid does influenza virus have?
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helical
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What is the form of the influenza genome?
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ssRNA
8 pieces (segmented) |
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Which translated protein is not encapsidated into viral particles?
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NS
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What is the probability that a ssRNA virus undergoes recombination?
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1/10^9
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What is the possibility that influenza recombines?
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50%
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Which two genes in a vaccine (e.g. Flu mist) should be included from the strain you want protection against?
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HA
NA |
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What must the other 6 genes be from?
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an attenuated flu virus
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What is the reservoir for Influenza A?
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waterfowl
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What is the total biomass of influenza A?
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about the size of a baseball -- 99.9% infect waterfowl!!
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What part of birds gets infected by flu?
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the cloaca
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Does influenza A normally cause disease in birds?
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no!
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Which flu caused the Stanley cup finals to be cancelled?
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1918 Spanish flu (in 1919)
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What was uncommon about the 1918 flu strain?
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commonly killed young and healthy persons
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What were some symptoms of Spanish flu?
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-cyanosis (blue from lack of O2)
-hemoptysis (spitting up blood) -ARDS (adult respiratory distress syndrome) |
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What was the peak in age of deaths from Spanish flu?
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age 10-50
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What was the main cause of mortality in younger people?
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ARDS (cytokine storm)
die from immune response! |
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What was the main cause of death in older people?
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death from secondary bacterial infection (pneumoniae)
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What was a neural effect of Spanish flu?
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psychiatric disorders
encephalitis lethargica (conscious paralysis) |
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How many people died from Spanish flu in the first 6 months?
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25 million
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What was the global mortality rate?
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2-6%
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What island suffered a loss of 22% of its population in 14 days?
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Fiji
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Describe the origin of the current H1N1 virus:
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-3 strains: classic swine H1N1, human H3N2 and an unknown avian flu recombined
-These generated: North American H3N2, and H1N2 -These recombined with Eurasian swine flu |
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Where do the HA and the NA derive in the 2009 swine flu?
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-H1 - classic swine flu
-N1 - Eurasian swine flu |
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Where did this virus really originate?
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China (not Mexico)
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Why has a pandemic developed?
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-most people in the world do not have immunity
-good P-to-P spread -disease-causing |
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Where have all the major pandemics we know of started from?
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China
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What is a likely reason for pandemics starting in China?
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-culinary habbits
-close contact of pigs, poulty, and people |
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The 1957 and 1967 pandemic strains arose from recombination of flu viruses from which species?
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humand and birds
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Why would Peking duck be a cause of new flu pandemics?
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chefs blow into cloaca
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Who first tried to isolate the original 1918 flu virus?
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Johan Hultin
He failed - viruses at Brevig mission were dead... |
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Who tried next?
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Jeffrey Taubenberger
Used PCR ...succeeded |
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What was discovered about Spanish flu from PCR?
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-It was a pure avian strain!
-Only 23 a.a. changes out of 5 672 |
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What was different about the resurrected 1918 flu compared with recent flu strains?
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-50 times as many virus particles releases from human lung cells
-32% more body is lost by mice -3900x more virus particles in mouse (4d.) -all mice die after 6 days (usually, none die) |
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What strain is Avian flu?
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H5N1
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When was Avian flu first detected in China?
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1996
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Which species of bird flu were assorted to make avian flu?
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goose
quail duck |
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Why was avian flu feared? Why were the date not necessary representative?
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killed 6/18 infected humans
unrepresentative denominator |
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How was Avian flu eradicated in 1997?
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by killing all the poultry
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What changes in the Avian flu took place from 1997-2002?
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different internal genes from duck and goose
(same H1 N5) |
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What was special about the avian flu of 2002?
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the H5N1 flu killed wildfowl in Hong Kong!!!
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What happened when this strain spread to humans?
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killed 1/2 humans infected!!
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What was the 2002 avian flu called?
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Z genotype
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How many birds have been killed to date?
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240 million domesticated birds
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How many humans have been infected/died?
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1300 infected
150 dead |
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What new properties has Avian flu gained?
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-capability to infect humans
-cause neurotropic damage and mortality in waterfowl -cause death and can be transmitted in felion species -cause neurotropic disease/death in mice |
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Why has Avian flu not been as severe as predicted?
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cannot predent person-to-person!!
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What are the requirements to produce a pandemic strain as pathogenic as Spanish flu?
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1. No/little human immunity to HA proteins
2. HA - facile infection of non-respiratory tissues 3. HA - higher affinity to human sialic acid than avian sialic acid 4. Easy RNA synthesis in human cells 5. NS1 -high level of apoptosis; high inhibition of IFN induction 6. Severe pro-inflammatory effects 7. Easily infect humans 8. Significant disease in humans 9. Spread easily P-to-P |
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Why could a vaccination insufficient to protect against a pandemic similar to Spanish flu?
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Takes about 8 months to develop a vaccine
Less than 2 months to declare a pandemic! |
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How does Amantidine/Rimantidine work? It is used?
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-inhibits viral uncoating
-H1N1 is resistant, H3N2 frequently, H5N1 frequently |
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How does Tamiflu (Oseltamivir)/Zanamivir work?
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-NA inhibitor
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Name a virus that has dsRNA:
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reovirus
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Name two (-)ssRNA viruses that are segmented:
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orthymyxoviruses
bunyaviruses |
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Name two (+)ssRNA viruses:
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coronaviruses (colds)
picornaviruses (polio, rhino, flu) |
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Name two (-)ssRNA viruses/non-segmented:
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rhabdo (rhabies)
paramixoviruses (measles, mumps) |
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Which type of RNA viruses can use their genome directly:
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(+)ssRNA
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Why type of RNA virus is independent of protein translation?
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(-)ssRNA
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What phases of transcription exist in (-)ssRNA?
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early phase (mRNA)
late phase (ssRNA associates with NP and 3"P" protease) |
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What do the 8 RNAs in influenza code for?
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PA1- polymerase acidic
PA2 - polymerase acidic PB2 - polymerase basic HA - hemagglutinin NP - nucleocapsid protein NA - neuraminidase M1 - NS1 - increase apoptosis/decrease IFN |
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What are three functions/effects of HA?`
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1. receptor-binding (sialic acid)
2. coagulates RBCs 3. membrane fusion activity allowing viral uncoating |
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How HA organized?
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in trimers
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Why must flu replication take place in the nucleus of the host cell?
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-mRNA requires splicing
-mRNA requires primers (newly synthesized host RNAs) |
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What are the two roles of NS1?
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-increases apoptosis
-decreases interferon |
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Which two viral proteins are spliced?
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NS
M |
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What does NS2 do?
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function unclear
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What does M2 do?
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-TM protein
-ion channel protein -low expression -pumps H+ into viral particle to allow uncoating |
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What does NA do?
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-digests neuraminic acid on cell surface
-receptor-destroying protein -prevent viruses from sticking to production cell -prevents aggregation of newly formed virions |
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Which two methods do viruses use to enter cells?
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-direct membrane fusion (measles)
-endocytosis (flu) |
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Which method does flu use?
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endocytosis
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What pH does HA bind to sialic acid at?
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7.4
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What pH is required to allow uncoating?
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~3.0
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Which organelle allows lowering of pH?
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fusion of lysosome
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Why is uncoating pH dependent?
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NP is bound by ionic interactions to M1
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What viral protein allows H+ ions to be pumped into the virus particle so NP can be released?
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M2
pH surrounding = 7.4 pH inside = 3.0 |
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What anti-viral drug interferes with the M2 pump?
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amantidine
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Which areas of HA are most antigenically variable?
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areas right next pocket where sialic acid fits (Fab is too small to fit)
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Which antiviral is an analog of neuraminic acid and fits into NA site?
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Tamiflu (Oseltamivir)
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