Exam 4 Influenza A, B, C Flashcards by Aditi Iyer

What are the characteristics of the influenza virus A?

Highly infectious
Several serotypes
144 subtypes
Associated with pandemic flu

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What are the characteristics of the influenza virus B?

One serotype classified into 2 lineages

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What are the characteristics of influenza virus C?

Mostly mild

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____ maybe infects humans

Influenza virus D

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Influenza A has a ____ range of hosts

Wide

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Influenza B has a ____ range of hosts

Small

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What do all of the influenza A viruses have in common?

H and N

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What are the subtypes of influenza A based on?

Based on H and N proteins

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How many subtypes of influenza A are there?

144

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Which two influenza A subtypes included in the yearly vaccine?

A(H1N1) and A(H3N2)

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The influenza A subtypes are a combination of:

H and N numbers

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There are ____ different hemagglutinins and ____ different neuraminidases in various Influenza A subtypes

18; 11

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What are the five components to the name of the virus strain?

Virus type
Geographic origin
Strain number
Year of isolation
Virus subtype

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What are the two lineages of Influenza B?

Victoria and Yamagata

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How many hemagglutinins are there?

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How many neuraminidases are there?

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What does hemagglutinin do?

Forms attachments to sialic acid on host cell membrane

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What does neuraminidase do?

Cleaves neuraminic/sialic acid, releases virion by budding

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What can happen with Influenza segmented RNA genome segments?

Reassortment

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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