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Immunology > Respiratory Viruses > Flashcards

Respiratory Viruses Flashcards

1
Q

Respiratory Viruses

A

Influenza virus

Rhinovirus

Coronavirus

Parainfluenza virus

Respiratory synctial virus

Metapneumovirus

Adenovirus (sometimes)

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2
Q

Virus families

A
  1. Picornaviridae (rhinovirus, coxsackie virus, echovirus, enterovirus)
  2. Coronaviridae (coronavirus, SARS-CoV)
  3. Orthomyxoviridae (Influenza A,B,C virus)
  4. Paramyxoviridae (Parainfluenza virus, respiratory synctial virus, metapneumovirus, measles virus)
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3
Q

Orthomyxovirus

Family:

Genus:

Individual Strain:

Subtypes:

Types:

A

Family: Orthomyxovirus

Genus: Influenza; Thogotovirus

Individual Strain: A/BAngkok/1/79(H3N2)

Subtypes: Based on hemagglutinin and neuramidase

Types: Based on matrix and nucleoprotein antigens

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4
Q

Antigenic Drift

A

Minor changes in either the hemagglutinin or neuramidase, or both

  • Minor antigenic variations reslut from mutations in hemagglutinin and neuraminidase genes
  • The hemagglutinin mutations are primarily found in the four antibody combining sites in the hemagglutinin protein
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5
Q

Major antigenic shift

A

Occurs infrequently, either hemagglutinin alone or neuraminidase as well. Occurs as a result of gene reassortment between a human and animal strain

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6
Q

Influenza Pathogenesis

A
  • Influenza is an acute respiratory disease
  • infects ciliated epithelial cells lining the upper respiratory tract, trachea, bronchi
  • Virus replication - destruciton of respiratory epithelium
  • Cell damage also due to virus activated CTL
  • Viremia - not a major role
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7
Q

Acute influenza infection in adults - symptoms

A

Rapid onset of fever, malaise, myalgia sore throat and nonproductive cough

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8
Q

Acute influenza infection in children

A

Acute disease similar to that in adults but with higher fever, GI tract symptoms, otitis media, myositis

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9
Q

Complications of influenza virus infection

A

Primary viral pneumonia

Secondary bacterial pneumonia

Myositis and cardiac involvement

Neurologic syndromes

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10
Q

Influenza diagnosis

A
  • Clinical signs and epidemiology
  • Lab diagnosis
    • Rapid antigen capture detects nucleoprotein (15 min)
    • rt-PCR
    • Hemagglutination/ Serology
    • Virus isolation
    • Immunofluorescent techniques
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11
Q

Replication and Spread of influenza (7 steps)

A
  1. Binding
  2. Coating/Fusing
  3. Transcription
  4. Proteins synthesized
  5. Replication
  6. Assembly
  7. Budding
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12
Q

What is the influenza virus cellular receptor?

A

Sialic acid

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13
Q

How does the viral membrane fuse with the vesicular membrane inside the cell?

A

Lowers the pH which triggers fusion and release of contents

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14
Q

Prevention and control of influenza: Immunization

A
  1. Formalin inactivated - mixture of prevalent antigenic types
  2. Attenuated infectious viruses - intranasal administration
  3. Experimental - DNA vaccines - reverse transcriptase
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15
Q

Prevention and control of influenza: Chemotherapy

A
  1. Amantadine and rimantadine - inhibit uncoating by blocking M2 protein
  2. Ribavirin - inhibits syntehsis of viral RNA
  3. Zanamivir and Oseltamivir (Tamiflu) neuraminidase inhibitors
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16
Q

Influenza is usually treated with a _______ vaccine

A

Trivalent

17
Q

Rhinovirus (characteristics)

A
  • Causes 50% of common colds
  • >150 serotypes identified
  • Temperature sensitive - grows better at 33º than 37º
  • Secretory IgA is most important in limiting reinfection
  • Transmission by respiratory secretions
18
Q

Rhinovirus symptoms

A
  • Headache
  • Cough
  • Sore throat
  • Mucus
  • Nasal discharge

All due to inflammatory response

19
Q

Rhinovirus prevention and control

A

No effective prevention and control measures to date

  • Experimental
    • Viral protease inhibitors (Ruprintrivir)
    • WIN compounds - block uncoating by inserting in virus surface pore
20
Q

Rhinoviruses are transmitted via _______

A

fomites

21
Q

Coronaviruses (characteristics)

A

Cause common colds - watery eyes, sneezing, nasal congestion, sore throat

Disesae limited to upper respiratory tract, infects epithelial cells

No vaccine available

22
Q

Coronavirus Outbreaks

A
  • 2002-2003: SARS outbreak caused by SARS-CoV
  • 2012 - acute pneumonia and renal failure MERS-CoV originally named hCoV EMC
23
Q

Coronavirus - SARS

Fatality Rate:

Transmission:

Source:

Vaccines:

A

Sudden acute respiratory syndrome

Fatality Rate: 10%

Transmission: Mainly by face-to-face contact; virus in respiratory secretions and feces; not highly contagious

Source: Bats, and other animals sold in markets in China

Vaccines: none currently available

24
Q

MERS-CoV

Difference from SARS:

First Reported:

Origin:

Cases to date:

A

Middle East Respiratory Syndrome

Difference from SARS:

  • Uses a different cellular receptor
  • Does not readily pass from person to person

First Reported: September 2012 (May 2014-US)

Origin: Middle East (nosocomial infections documented)

Cases to date: 400

25
Q

Paramyxoviridae Family

A

Morbillivirus

Paramyxovirus

Pneumovirus

Heniparvirus

26
Q

Paramyxovirus family virus proteins

A

F: fusion protein

HN: Hemagglutinin virus attachment

Neuraminidase virus release

NS1 and NS2: Nonstructural proteins that modulate the immune response important in vivo

27
Q

Paramyxoviruses replicate in the ______

A

cytoplasm

28
Q

Human Parainfluenza Viruses (HPIV) - key issues

A
  • Common cause of acute and lower respiratory illness in infants/young children/elderly/immunocompromised
  • Common cause of croup
  • Different types (HPIV1, HPIV2, HPIV3, HPIV4)
  • Reverse genetics systems for HPIVs have helped attenuating mutations and to incrementally attenuate
  • Vaccines have entered pediatric trials in Phase 1
29
Q

Paramyxoviridae - Respiratory Synctial virus (RSV)

A
  • Most common cause of fatal acute respiratory tract infection in infants and young children
  • Infects virtually everyone by age 2
  • Re-infections occur throughout life, can be severe in elderly
30
Q

Disease mechanisms of Respiratory Syncytial Virus

A
  • Pneumonia results from cytopathologic spread of virus (including syncytia)
  • Bronchiolitis is most likely mediated by host’s immune response
  • Narrow airways of young infants are readily obstructed by virus-induced pathologic effects
  • Maternal antibody does not protect infant from infection
31
Q

RSV - pathogenesis

A

Typical giant cells - pink intracytoplasmic inclusions

32
Q

Immune response in infants vs adults to RSV

A
  • Infants
    • TH2 response
    • Mast cell activation
    • Eosinophila
    • Wheezing
  • Adults
    • Th1 response - IFN
    • Macrophages, NK cells, Cell mediated immunity
    • B cells
    • Cytolysis
    • Antiviral cytokines
    • Virus clearance
33
Q

RSV treatment prevention and control

Otherwise healthy infant:

Premature or immunocompromised infants:

Premature infants:

Vaccine:

A

Otherwise healthy infant: treatment is supportive, oxygen, IV fluids, nebulized cold steam

Premature or immunocompromised infants: Aerosolized ribarin

Premature infants: Passive immunization with anti-RSV Ig and humanized monoclonal antibodies against viral fusion protein

Vaccine: No vaccine currently available

34
Q

Human Metapneumovirus - hMPV (Characteristics)

A

First identified in 2001

Clinical spectrum of disease similar to RSV - most severe in infants, elderly, immunocompromised, those with COPD

Second most common cause of lower RTI in young children

By 5 years of age all children are seropositive

35
Q

hMPV treatment and prevention

A
  • Most treatment is supportive
  • Ribavirin - inhibitory activity against hMPV
  • Immunoglobulins
    • IVIG
    • Humanized monoclonals
    • Ribavirin + IVIG
36
Q

Paramyxoviridae - Hendra and Nipah Virus

A

Two emerging respiratory viruses with high mortality rates

Have made the apparent jump from bats to people in Australia and Asia

37
Q

Adenovirus (Characteristics)

A
  • >50 human types identified
  • Cause a wide spectrum of disease including respiratory infection
    • Conjunctivitis
    • GI infections
    • Hemorrhagic cystitis
  • In respiratory tract, can cause destructive productive infection, persistent infection with virus shedding, or latent infections
38
Q

In addition to previously mentioned groups, ______ ______ are also highly susceptible to adenoviruses

A

military recruits

Immunology (17 decks)

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