Exam 4 Influenza A, B, C Flashcards
What are the characteristics of the influenza virus A?
- Highly infectious
- Several serotypes
- 144 subtypes
- Associated with pandemic flu
What are the characteristics of the influenza virus B?
One serotype classified into 2 lineages
What are the characteristics of influenza virus C?
Mostly mild
____ maybe infects humans
Influenza virus D
Influenza A has a ____ range of hosts
Wide
Influenza B has a ____ range of hosts
Small
What do all of the influenza A viruses have in common?
H and N
What are the subtypes of influenza A based on?
Based on H and N proteins
How many subtypes of influenza A are there?
144
Which two influenza A subtypes included in the yearly vaccine?
A(H1N1) and A(H3N2)
The influenza A subtypes are a combination of:
H and N numbers
There are ____ different hemagglutinins and ____ different neuraminidases in various Influenza A subtypes
18; 11
What are the five components to the name of the virus strain?
- Virus type
- Geographic origin
- Strain number
- Year of isolation
- Virus subtype
What are the two lineages of Influenza B?
Victoria and Yamagata
How many hemagglutinins are there?
18
How many neuraminidases are there?
11
What does hemagglutinin do?
Forms attachments to sialic acid on host cell membrane
What does neuraminidase do?
Cleaves neuraminic/sialic acid, releases virion by budding
What can happen with Influenza segmented RNA genome segments?
Reassortment
Influenza contains a single RNA gene wrapped around _____
Nuclear protein
What is antigenic drift?
Small genetic point mutations in H and N
Why do we need a new flu vaccine each season?
Due to antigenic drift
What does reassortment with RNA segments potentially lead to?
- Pandemic
- Reassortment can involve new combinations of RNA segments from dif viral strains
What is antigenic shift?
Abrupt, major change in influenza A
Antigenic shift can lead to a pandemic due to:
Little/no immunity to new virus
____ can undergo antigenic drift and shift to cause pandemics
Influenza A
____ can only undergo antigenic drift
Influenza B
Are there more influenza or COVID-19 deaths?
COVID-19
How long does it take influenza antibodies to develop after vaccination?
2 weeks
What are the 3 types of ways that influenza vaccines can be developed?
- Egg-based: need large numbers of eggs
- Cell-culture: grow human cells infected with whole virus in tanks
- Recombinant DNA: deliver hemagglutinin genes in adenovirus vector
What are the 4 strains in a quadrivalent flu vaccine?
- H1N1
- H3N2
- B/Victoria lineage
- B/Yamagata lineage
The quadrivalent flue vaccine has ____ components comprised of __ + ___ strains
4; 2A + 2B
What types of flu vaccines are available?
- Intramuscular injection (subunit, killed virus)
- Intranasal (live attenuated)
The intramuscular flu vaccine is a ___ dose for age > 65 years
High
Who is the flu vaccine recommended for?
Health care providers (HCP) & health care workers (HCW)
Young children 6-59 months
Women who will be pregnant during flu season
Persons age >50 years
Influenza causes severe disease for high risk populations, such as:
Croup (swelling of windpipe)
Influenza can cause secondary complications such as ____ infections. Patients become more susceptible to _____
Bacterial; Pneumonia-causing bacteria (S. pneumoniae, H. influenzae)
____ often follows the flu
Bacterial pneumonia
90% annual influenza death occurs in:
Elderly age > 65 years
What medications can be used for treatment of flu? What do they inhibit?
- Zanamivir (Relenza), Oseltamivir (Tamiflu), Peramivir (Rapivab)
- Inhibit neuraminidase to prevent virion release
Which medication is used for treatment of flu and is administered via an IV?
Peramivir (Rapivab) – single IV dose
When is Peramivir (Rapivab) used?
If non-compliant for oral medication or requiring IV administration
How are zanamivir and oseltamivir administered?
Orally
Why were there more influenza deaths in 1918 than in 1957?
Penicillin was not invented until the 1940s
What virus caused a pandemic in 1968?
H3N2
What virus caused a pandemic in 2009?
H1N1pdm09
____ and ____ viruses undergo regular antigenic drift and are therefore currently in the seasonal flu vaccine
H3N2; H1N1pdm09
What strains are predicted to cause the next flu pandemic?
- H5N1
- H7N7
- H9N2
(so far they inefficiently transmit human to human)
Human H5N1 cases are mostly found in what areas of the world?
Asia, some parts of Europe and Africa
