Influenza Flashcards by Joram Manio

Influenza Major Serotypes

A, B, C

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Influenza Order

Mononegavirales

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Family

Orthomyxoviridae

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Genera

Influenzavirus

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Structure

Spherical, pleomorphic

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Characteristics

Enveloped, ssRNA negative-strand virus

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Capsid

Helical

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Capsid Assembly

Citoplasm

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Segments are monocistronic except___ and ______

Non
structural (NS1, NS2), Matrix (M1, M2)
genes

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Influenza A & B virus has ____ segments which is ____

8, complete

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Influenza C has ____ segments

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Unique Properties of Influenza (4 traits)

High mutability
Genetic diversity
Genetic reassortment
Antigenic change

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Where does RNA transcription and translation take place?

Nucleus

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What are envelope glycoprotein spikes?

Hemagglutinin (HA)
Neuraminidase (NA)

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Function of HA (haemagglutinin)

Viral entry into target cell

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Function of (NA) neuraminidase

Release of viral particles from target cells and help in dissemination of virion particles throughout respiratory tract

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Function of PA (acidic polymerase protein)

Endonuclease activity and help in cap snatching mechanism

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Function of PB1 (basic polymerase protein - 1)

Viral mRNA transcription by 5’ cap snatching mechanism

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Function of PB2 (basic polymerase protein - 2)

Unprimed replication of viral mRNA

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Function of PB1-F2

Apoptosis of Host Cell

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Function of M1 (Matrix Protein)

Role of attachment of vNRP to cell membrane and provide stability

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Function of M2 (ion-channel protein)

Help in releasing vRNP from endosome to cytoplasm

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Function of NP (nucleoprotein particle)

Participate in the nuclear import and export of vRNP and viral replication

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Function of NS1 (nonstructural protein - 1)

Suppress IFN-Beta and host protein production

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Function of NS2 (nonstructural protein - 2)

Help in nuclear import of vRNP

Surface glycoproteins are _____ and serve _______

antigenic, Special functional importance to the virus

The high frequency of variations of these two result in new serologic types

Hemagglutinin and Neuraminidase

Function of Hemagglutinin

*Binding to host receptor * Internalization of the virus *Facilitation of membrane fusion events *Target of neutralizing antibodies

__, __, and __ are most associated with human infection

H1, H2, H3

Function of Neuraminidase

*Hydrolyzes the mucus on respiratory epithelium *Destroys unoccupied hemagglutinin receptors

__ and __ are most associated with human infection

N1 and N2

Only type ____ has subtypes

How many HA subtypes are there and how many affect humans?

16 HA, 4 affect humans (H1-H3, H5)

How many NA subtypes are there and how many affect humans?

9 NA, 2 affect humans (N1, N2)

What type of flu is H1N1? (Seasonal, Pandemic, Zoonotic)

Seasonal, Pandemic, Zoonotic

What type of flu is A(H3N2)? (Seasonal, Pandemic, Zoonotic)

Seasonal, Zoonotic

What type of flu is Spanish flu? (Seasonal, Pandemic, Zoonotic)

Pandemic

What type of flu is Type B and C? (Seasonal, Pandemic, Zoonotic)

Seasonal

Lineage of Type B influenza

Victoria and Yamagata

What type of flu is H5N1 and H9N2? (Seasonal, Pandemic, Zoonotic)

Zoonotic

Major Reservoirs of Influenza

Birds, swine, horses, dogs, cats, domestic poultry

Minor Changes - antigenic _____; Majora Changes - antigenic _____

drift, shift

What happens in antigenic drift?

* minor mutations in the hemagglutinin antigen * makes prior immunity less effective * Occurs among influenza A viruses

What happens in antigenic shift?

* major changes occur in surface antigens that occurs by reassortment * virus strains appear more different antigenically from previously seen strains; makes prior immunity less effective

TRUE OR FALSE: Antigenic drift occurs in all influenza viruses

FALSE, only influenza A

Influenza transmission happens through ___

coughing and sneezing

Children can be infectious for ___ days

=> 10

Young children can shed virus for __ days before their illness onset

=<6

Severely immunocompromised persons can shed virus for _____

weeks or months

Adults infectious from the day ____

before symptoms begin until 5 days after illness onset

Theories for the emergence of pandemic viruses

*Genetic reassortment between human and animal viruses *Direct transfer of viruses between animals and humans *Re-emergence of viruses from unrecognized or unsuspected reservoirs.

Also known as the avian strain

H5N1

"swine flu" and also known as influenza ____, emerged in Mexico

A/H1N1

__ and __ subtypes are known to cause the highly pathogenic form of the disease

H5 and H7

Influenza A (H7N9) circulate among ____

birds

Transmission of Influenza A(H7N9)

respiratory droplets or contact

TRUE OR FALSE: Influenza A(H7N9) is considered to be low pathogenic avian influenza

TRUE

In March 2013, there was an Influenza A(H7N9) in what country?

China

In the Philippines, what influenza strand affected a cumulative of 24 provinces?

H5N1

Strand H5N6 affected which province?

Guimba, Nueva Ecija

Strand H7N7 affected which province?

Mexico, Pampanga

Influenza causes the cellular ____ and _______ of superficial mucosa

destruction, desquamation

Influenza can lead to ____

Secondary bacterial superinfection

In influenza pathogenesis, there is a disruption of ____

mucociliary escalator

Local symptomatic phase

cellular damage, edema

Systemic symptomatic phase

cytokines, interferon

HA binding, endocytosis, M2 ion channel, HA2 fusion peptide are terms correlated in what part of pathogenesis?

Attachment, Penetration, and Uncoating

In transcription and translation, nucleocapsid ____ the _____

enters. nucleus

In transcription and translation, RNA polymerase transcribes ____ to _____

(-) ssRNA, (+) ssRNA

What happens in viral replication

* (+) ssRNA acts as a template to produce new (-) ssRNA. * Nucleocapsid forms with viral RNA and NP proteins.

In maturation and release, _____ is exported to ______

nucleocapsid, cytoplasm

In maturation and release, __ and __ is inserted into host cell membrane

HA & NA

Incubation period length

2 days (range 1-4 days)

Symptoms of Influenza

Abrupt onset of fever, myalgia, sore throat, nonproductive cough, headache

Immunity depends on __________ and ___________

immunity to previous variant circulating in population and on relatedness of the two variants

Most epidemics are due to antigenic (drift/shift)

shift

Antibody against H protein: protective; Ab against N protein: ____

Disease severity

Diagnostic Tests for influenza

* Viral culture * Serology * Rapid antigen testing * polymerase chain reaction (PCR) * Immunofluorescence

TRUE OR FALSE: Throat swab specimens are typically more effective than nasopharyngeal specimens

False, opposite

Treatment

Neuraminidase inhibitors (NAIs) Oseltamivir and Zanamivir

Treatment is beneficial for:

* pregnant patients * patients with progressing lower respiratory disease or pneumonia * patients with underlying medical conditions